/*
===========================================================================

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company.

This file is part of the Doom 3 GPL Source Code ("Doom 3 Source Code").

Doom 3 Source Code is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Doom 3 Source Code is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/

#include "sys/platform.h"
#include "renderer/VertexCache.h"

#include "renderer/tr_local.h"

extern idCVar r_useCarmacksReverse;
extern idCVar r_useStencilOpSeparate;

/*
=====================
RB_BakeTextureMatrixIntoTexgen
=====================
*/
void RB_BakeTextureMatrixIntoTexgen( idPlane lightProject[3], const float *textureMatrix ) {
	float	genMatrix[16];
	float	final[16];

	genMatrix[0] = lightProject[0][0];
	genMatrix[4] = lightProject[0][1];
	genMatrix[8] = lightProject[0][2];
	genMatrix[12] = lightProject[0][3];

	genMatrix[1] = lightProject[1][0];
	genMatrix[5] = lightProject[1][1];
	genMatrix[9] = lightProject[1][2];
	genMatrix[13] = lightProject[1][3];

	genMatrix[2] = 0;
	genMatrix[6] = 0;
	genMatrix[10] = 0;
	genMatrix[14] = 0;

	genMatrix[3] = lightProject[2][0];
	genMatrix[7] = lightProject[2][1];
	genMatrix[11] = lightProject[2][2];
	genMatrix[15] = lightProject[2][3];

	myGlMultMatrix( genMatrix, backEnd.lightTextureMatrix, final );

	lightProject[0][0] = final[0];
	lightProject[0][1] = final[4];
	lightProject[0][2] = final[8];
	lightProject[0][3] = final[12];

	lightProject[1][0] = final[1];
	lightProject[1][1] = final[5];
	lightProject[1][2] = final[9];
	lightProject[1][3] = final[13];
}

/*
================
RB_PrepareStageTexturing
================
*/
void RB_PrepareStageTexturing( const shaderStage_t *pStage,  const drawSurf_t *surf, idDrawVert *ac ) {
	// set privatePolygonOffset if necessary
	if ( pStage->privatePolygonOffset ) {
		qglEnable( GL_POLYGON_OFFSET_FILL );
		qglPolygonOffset( r_offsetFactor.GetFloat(), r_offsetUnits.GetFloat() * pStage->privatePolygonOffset );
	}

	// set the texture matrix if needed
	if ( pStage->texture.hasMatrix ) {
		RB_LoadShaderTextureMatrix( surf->shaderRegisters, &pStage->texture );
	}

	// texgens
	if ( pStage->texture.texgen == TG_DIFFUSE_CUBE ) {
		qglTexCoordPointer( 3, GL_FLOAT, sizeof( idDrawVert ), ac->normal.ToFloatPtr() );
	}
	if ( pStage->texture.texgen == TG_SKYBOX_CUBE || pStage->texture.texgen == TG_WOBBLESKY_CUBE ) {
		qglTexCoordPointer( 3, GL_FLOAT, 0, vertexCache.Position( surf->dynamicTexCoords ) );
	}
	if ( pStage->texture.texgen == TG_SCREEN ) {
		qglEnable( GL_TEXTURE_GEN_S );
		qglEnable( GL_TEXTURE_GEN_T );
		qglEnable( GL_TEXTURE_GEN_Q );

		float	mat[16], plane[4];
		myGlMultMatrix( surf->space->modelViewMatrix, backEnd.viewDef->projectionMatrix, mat );

		plane[0] = mat[0];
		plane[1] = mat[4];
		plane[2] = mat[8];
		plane[3] = mat[12];
		qglTexGenfv( GL_S, GL_OBJECT_PLANE, plane );

		plane[0] = mat[1];
		plane[1] = mat[5];
		plane[2] = mat[9];
		plane[3] = mat[13];
		qglTexGenfv( GL_T, GL_OBJECT_PLANE, plane );

		plane[0] = mat[3];
		plane[1] = mat[7];
		plane[2] = mat[11];
		plane[3] = mat[15];
		qglTexGenfv( GL_Q, GL_OBJECT_PLANE, plane );
	}

	if ( pStage->texture.texgen == TG_SCREEN2 ) {
		qglEnable( GL_TEXTURE_GEN_S );
		qglEnable( GL_TEXTURE_GEN_T );
		qglEnable( GL_TEXTURE_GEN_Q );

		float	mat[16], plane[4];
		myGlMultMatrix( surf->space->modelViewMatrix, backEnd.viewDef->projectionMatrix, mat );

		plane[0] = mat[0];
		plane[1] = mat[4];
		plane[2] = mat[8];
		plane[3] = mat[12];
		qglTexGenfv( GL_S, GL_OBJECT_PLANE, plane );

		plane[0] = mat[1];
		plane[1] = mat[5];
		plane[2] = mat[9];
		plane[3] = mat[13];
		qglTexGenfv( GL_T, GL_OBJECT_PLANE, plane );

		plane[0] = mat[3];
		plane[1] = mat[7];
		plane[2] = mat[11];
		plane[3] = mat[15];
		qglTexGenfv( GL_Q, GL_OBJECT_PLANE, plane );
	}

	if ( pStage->texture.texgen == TG_GLASSWARP ) {
		if ( tr.backEndRenderer == BE_ARB2 /*|| tr.backEndRenderer == BE_NV30*/ ) {
			qglBindProgramARB( GL_FRAGMENT_PROGRAM_ARB, FPROG_GLASSWARP );
			qglEnable( GL_FRAGMENT_PROGRAM_ARB );

			GL_SelectTexture( 2 );
			globalImages->scratchImage->Bind();

			GL_SelectTexture( 1 );
			globalImages->scratchImage2->Bind();

			qglEnable( GL_TEXTURE_GEN_S );
			qglEnable( GL_TEXTURE_GEN_T );
			qglEnable( GL_TEXTURE_GEN_Q );

			float	mat[16], plane[4];
			myGlMultMatrix( surf->space->modelViewMatrix, backEnd.viewDef->projectionMatrix, mat );

			plane[0] = mat[0];
			plane[1] = mat[4];
			plane[2] = mat[8];
			plane[3] = mat[12];
			qglTexGenfv( GL_S, GL_OBJECT_PLANE, plane );

			plane[0] = mat[1];
			plane[1] = mat[5];
			plane[2] = mat[9];
			plane[3] = mat[13];
			qglTexGenfv( GL_T, GL_OBJECT_PLANE, plane );

			plane[0] = mat[3];
			plane[1] = mat[7];
			plane[2] = mat[11];
			plane[3] = mat[15];
			qglTexGenfv( GL_Q, GL_OBJECT_PLANE, plane );

			GL_SelectTexture( 0 );
		}
	}

	if ( pStage->texture.texgen == TG_REFLECT_CUBE ) {
		if ( tr.backEndRenderer == BE_ARB2 ) {
			// see if there is also a bump map specified
			const shaderStage_t *bumpStage = surf->material->GetBumpStage();
			if ( bumpStage ) {
				// per-pixel reflection mapping with bump mapping
				GL_SelectTexture( 1 );
				bumpStage->texture.image->Bind();
				GL_SelectTexture( 0 );

				qglNormalPointer( GL_FLOAT, sizeof( idDrawVert ), ac->normal.ToFloatPtr() );
				qglVertexAttribPointerARB( 10, 3, GL_FLOAT, false, sizeof( idDrawVert ), ac->tangents[1].ToFloatPtr() );
				qglVertexAttribPointerARB( 9, 3, GL_FLOAT, false, sizeof( idDrawVert ), ac->tangents[0].ToFloatPtr() );

				qglEnableVertexAttribArrayARB( 9 );
				qglEnableVertexAttribArrayARB( 10 );
				qglEnableClientState( GL_NORMAL_ARRAY );

				// Program env 5, 6, 7, 8 have been set in RB_SetProgramEnvironmentSpace

				qglBindProgramARB( GL_FRAGMENT_PROGRAM_ARB, FPROG_BUMPY_ENVIRONMENT );
				qglEnable( GL_FRAGMENT_PROGRAM_ARB );
				qglBindProgramARB( GL_VERTEX_PROGRAM_ARB, VPROG_BUMPY_ENVIRONMENT );
				qglEnable( GL_VERTEX_PROGRAM_ARB );
			} else {
				// per-pixel reflection mapping without a normal map
				qglNormalPointer( GL_FLOAT, sizeof( idDrawVert ), ac->normal.ToFloatPtr() );
				qglEnableClientState( GL_NORMAL_ARRAY );

				qglBindProgramARB( GL_FRAGMENT_PROGRAM_ARB, FPROG_ENVIRONMENT );
				qglEnable( GL_FRAGMENT_PROGRAM_ARB );
				qglBindProgramARB( GL_VERTEX_PROGRAM_ARB, VPROG_ENVIRONMENT );
				qglEnable( GL_VERTEX_PROGRAM_ARB );
			}
		} else {
			qglEnable( GL_TEXTURE_GEN_S );
			qglEnable( GL_TEXTURE_GEN_T );
			qglEnable( GL_TEXTURE_GEN_R );
			qglTexGenf( GL_S, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP_EXT );
			qglTexGenf( GL_T, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP_EXT );
			qglTexGenf( GL_R, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP_EXT );
			qglEnableClientState( GL_NORMAL_ARRAY );
			qglNormalPointer( GL_FLOAT, sizeof( idDrawVert ), ac->normal.ToFloatPtr() );

			qglMatrixMode( GL_TEXTURE );
			float	mat[16];

			R_TransposeGLMatrix( backEnd.viewDef->worldSpace.modelViewMatrix, mat );

			qglLoadMatrixf( mat );
			qglMatrixMode( GL_MODELVIEW );
		}
	}
}

/*
================
RB_FinishStageTexturing
================
*/
void RB_FinishStageTexturing( const shaderStage_t *pStage, const drawSurf_t *surf, idDrawVert *ac ) {
	// unset privatePolygonOffset if necessary
	if ( pStage->privatePolygonOffset && !surf->material->TestMaterialFlag(MF_POLYGONOFFSET) ) {
		qglDisable( GL_POLYGON_OFFSET_FILL );
	}

	if ( pStage->texture.texgen == TG_DIFFUSE_CUBE || pStage->texture.texgen == TG_SKYBOX_CUBE
		|| pStage->texture.texgen == TG_WOBBLESKY_CUBE ) {
		qglTexCoordPointer( 2, GL_FLOAT, sizeof( idDrawVert ), (void *)&ac->st );
	}

	if ( pStage->texture.texgen == TG_SCREEN ) {
		qglDisable( GL_TEXTURE_GEN_S );
		qglDisable( GL_TEXTURE_GEN_T );
		qglDisable( GL_TEXTURE_GEN_Q );
	}
	if ( pStage->texture.texgen == TG_SCREEN2 ) {
		qglDisable( GL_TEXTURE_GEN_S );
		qglDisable( GL_TEXTURE_GEN_T );
		qglDisable( GL_TEXTURE_GEN_Q );
	}

	if ( pStage->texture.texgen == TG_GLASSWARP ) {
		if ( tr.backEndRenderer == BE_ARB2 /*|| tr.backEndRenderer == BE_NV30*/ ) {
			GL_SelectTexture( 2 );
			globalImages->BindNull();

			GL_SelectTexture( 1 );
			if ( pStage->texture.hasMatrix ) {
				RB_LoadShaderTextureMatrix( surf->shaderRegisters, &pStage->texture );
			}
			qglDisable( GL_TEXTURE_GEN_S );
			qglDisable( GL_TEXTURE_GEN_T );
			qglDisable( GL_TEXTURE_GEN_Q );
			qglDisable( GL_FRAGMENT_PROGRAM_ARB );
			globalImages->BindNull();
			GL_SelectTexture( 0 );
		}
	}

	if ( pStage->texture.texgen == TG_REFLECT_CUBE ) {
		if ( tr.backEndRenderer == BE_ARB2 ) {
			// see if there is also a bump map specified
			const shaderStage_t *bumpStage = surf->material->GetBumpStage();
			if ( bumpStage ) {
				// per-pixel reflection mapping with bump mapping
				GL_SelectTexture( 1 );
				globalImages->BindNull();
				GL_SelectTexture( 0 );

				qglDisableVertexAttribArrayARB( 9 );
				qglDisableVertexAttribArrayARB( 10 );
			} else {
				// per-pixel reflection mapping without bump mapping
			}

			qglDisableClientState( GL_NORMAL_ARRAY );
			qglDisable( GL_FRAGMENT_PROGRAM_ARB );
			qglDisable( GL_VERTEX_PROGRAM_ARB );
			// Fixme: Hack to get around an apparent bug in ATI drivers.  Should remove as soon as it gets fixed.
			qglBindProgramARB( GL_VERTEX_PROGRAM_ARB, 0 ); // FIXME ...
		} else {
			qglDisable( GL_TEXTURE_GEN_S );
			qglDisable( GL_TEXTURE_GEN_T );
			qglDisable( GL_TEXTURE_GEN_R );
			qglTexGenf( GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR );
			qglTexGenf( GL_T, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR );
			qglTexGenf( GL_R, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR );
			qglDisableClientState( GL_NORMAL_ARRAY );

			qglMatrixMode( GL_TEXTURE );
			qglLoadIdentity();
			qglMatrixMode( GL_MODELVIEW );
		}
	}

	if ( pStage->texture.hasMatrix ) {
		qglMatrixMode( GL_TEXTURE );
		qglLoadIdentity();
		qglMatrixMode( GL_MODELVIEW );
	}
}

/*
=============================================================================================

FILL DEPTH BUFFER

=============================================================================================
*/


/*
==================
RB_T_FillDepthBuffer
==================
*/
void RB_T_FillDepthBuffer( const drawSurf_t *surf ) {
	int			stage;
	const idMaterial	*shader;
	const shaderStage_t *pStage;
	const float	*regs;
	float		color[4];
	const srfTriangles_t	*tri;

	tri = surf->geo;
	shader = surf->material;

	// update the clip plane if needed
	if ( backEnd.viewDef->numClipPlanes && surf->space != backEnd.currentSpace ) {
		GL_SelectTexture( 1 );

		idPlane	plane;

		R_GlobalPlaneToLocal( surf->space->modelMatrix, backEnd.viewDef->clipPlanes[0], plane );
		plane[3] += 0.5;	// the notch is in the middle
		qglTexGenfv( GL_S, GL_OBJECT_PLANE, plane.ToFloatPtr() );
		GL_SelectTexture( 0 );
	}

	if ( !shader->IsDrawn() ) {
		return;
	}

	// some deforms may disable themselves by setting numIndexes = 0
	if ( !tri->numIndexes ) {
		return;
	}

	// translucent surfaces don't put anything in the depth buffer and don't
	// test against it, which makes them fail the mirror clip plane operation
	if ( shader->Coverage() == MC_TRANSLUCENT ) {
		return;
	}

	if ( !tri->ambientCache ) {
		common->Printf( "RB_T_FillDepthBuffer: !tri->ambientCache\n" );
		return;
	}

	// get the expressions for conditionals / color / texcoords
	regs = surf->shaderRegisters;

	// if all stages of a material have been conditioned off, don't do anything
	for ( stage = 0; stage < shader->GetNumStages() ; stage++ ) {
		pStage = shader->GetStage(stage);
		// check the stage enable condition
		if ( regs[ pStage->conditionRegister ] != 0 ) {
			break;
		}
	}
	if ( stage == shader->GetNumStages() ) {
		return;
	}

	// set polygon offset if necessary
	if ( shader->TestMaterialFlag(MF_POLYGONOFFSET) ) {
		qglEnable( GL_POLYGON_OFFSET_FILL );
		qglPolygonOffset( r_offsetFactor.GetFloat(), r_offsetUnits.GetFloat() * shader->GetPolygonOffset() );
	}

	// subviews will just down-modulate the color buffer by overbright
	if ( shader->GetSort() == SS_SUBVIEW ) {
		GL_State( GLS_SRCBLEND_DST_COLOR | GLS_DSTBLEND_ZERO | GLS_DEPTHFUNC_LESS );
		color[0] =
		color[1] =
		color[2] = ( 1.0 / backEnd.overBright );
		color[3] = 1;
	} else {
		// others just draw black
		color[0] = 0;
		color[1] = 0;
		color[2] = 0;
		color[3] = 1;
	}

	idDrawVert *ac = (idDrawVert *)vertexCache.Position( tri->ambientCache );
	qglVertexPointer( 3, GL_FLOAT, sizeof( idDrawVert ), ac->xyz.ToFloatPtr() );
	qglTexCoordPointer( 2, GL_FLOAT, sizeof( idDrawVert ), reinterpret_cast<void *>(&ac->st) );

	bool drawSolid = false;

	if ( shader->Coverage() == MC_OPAQUE ) {
		drawSolid = true;
	}

	// we may have multiple alpha tested stages
	if ( shader->Coverage() == MC_PERFORATED ) {
		// if the only alpha tested stages are condition register omitted,
		// draw a normal opaque surface
		bool	didDraw = false;

		qglEnable( GL_ALPHA_TEST );
		// perforated surfaces may have multiple alpha tested stages
		for ( stage = 0; stage < shader->GetNumStages() ; stage++ ) {
			pStage = shader->GetStage(stage);

			if ( !pStage->hasAlphaTest ) {
				continue;
			}

			// check the stage enable condition
			if ( regs[ pStage->conditionRegister ] == 0 ) {
				continue;
			}

			// if we at least tried to draw an alpha tested stage,
			// we won't draw the opaque surface
			didDraw = true;

			// set the alpha modulate
			color[3] = regs[ pStage->color.registers[3] ];

			// skip the entire stage if alpha would be black
			if ( color[3] <= 0 ) {
				continue;
			}
			qglColor4fv( color );

			qglAlphaFunc( GL_GREATER, regs[ pStage->alphaTestRegister ] );

			// bind the texture
			pStage->texture.image->Bind();

			// set texture matrix and texGens
			RB_PrepareStageTexturing( pStage, surf, ac );

			// draw it
			RB_DrawElementsWithCounters( tri );

			RB_FinishStageTexturing( pStage, surf, ac );
		}
		qglDisable( GL_ALPHA_TEST );
		if ( !didDraw ) {
			drawSolid = true;
		}
	}

	// draw the entire surface solid
	if ( drawSolid ) {
		qglColor4fv( color );
		globalImages->whiteImage->Bind();

		// draw it
		RB_DrawElementsWithCounters( tri );
	}


	// reset polygon offset
	if ( shader->TestMaterialFlag(MF_POLYGONOFFSET) ) {
		qglDisable( GL_POLYGON_OFFSET_FILL );
	}

	// reset blending
	if ( shader->GetSort() == SS_SUBVIEW ) {
		GL_State( GLS_DEPTHFUNC_LESS );
	}

}


void RB_SetProgramEnvironment( bool isPostProcess ); // so RB_STD_FillDepthBuffer() can use it

/*
=====================
RB_STD_FillDepthBuffer

If we are rendering a subview with a near clip plane, use a second texture
to force the alpha test to fail when behind that clip plane
=====================
*/
void RB_STD_FillDepthBuffer( drawSurf_t **drawSurfs, int numDrawSurfs ) {
	// if we are just doing 2D rendering, no need to fill the depth buffer
	if ( !backEnd.viewDef->viewEntitys ) {
		return;
	}

	// enable the second texture for mirror plane clipping if needed
	if ( backEnd.viewDef->numClipPlanes ) {
		GL_SelectTexture( 1 );
		globalImages->alphaNotchImage->Bind();
		qglDisableClientState( GL_TEXTURE_COORD_ARRAY );
		qglEnable( GL_TEXTURE_GEN_S );
		qglTexCoord2f( 1, 0.5 );
	}

	// the first texture will be used for alpha tested surfaces
	GL_SelectTexture( 0 );
	qglEnableClientState( GL_TEXTURE_COORD_ARRAY );

	// decal surfaces may enable polygon offset
	qglPolygonOffset( r_offsetFactor.GetFloat(), r_offsetUnits.GetFloat() );

	GL_State( GLS_DEPTHFUNC_LESS );

	// Enable stencil test if we are going to be using it for shadows.
	// If we didn't do this, it would be legal behavior to get z fighting
	// from the ambient pass and the light passes.
	qglEnable( GL_STENCIL_TEST );
	qglStencilFunc( GL_ALWAYS, 1, 255 );

	RB_RenderDrawSurfListWithFunction( drawSurfs, numDrawSurfs, RB_T_FillDepthBuffer );

	// Make the early depth pass available to shaders. #3877
	bool getDepthCapture = r_enableDepthCapture.GetInteger() == 1
		|| (r_enableDepthCapture.GetInteger() == -1 && r_useSoftParticles.GetBool());

	if ( getDepthCapture && backEnd.viewDef->renderView.viewID >= 0 ) // Suppress for lightgem rendering passes
	{
		globalImages->currentDepthImage->CopyDepthbuffer( backEnd.viewDef->viewport.x1,
														  backEnd.viewDef->viewport.y1,
														  backEnd.viewDef->viewport.x2 - backEnd.viewDef->viewport.x1 + 1,
														  backEnd.viewDef->viewport.y2 - backEnd.viewDef->viewport.y1 + 1, 
														  true );
		bool isPostProcess = false;
		RB_SetProgramEnvironment( isPostProcess );
	}

	if ( backEnd.viewDef->numClipPlanes ) {
		GL_SelectTexture( 1 );
		globalImages->BindNull();
		qglDisable( GL_TEXTURE_GEN_S );
		GL_SelectTexture( 0 );
	}

}

/*
=============================================================================================

SHADER PASSES

=============================================================================================
*/

/*
==================
RB_SetProgramEnvironment

Sets variables that can be used by all vertex programs

[SteveL #3877] Note on the use of fragment program environmental variables.
Parameters 0 and 1 are set here to allow conversion of screen coordinates to
texture coordinates, for use when sampling _currentRender.
Those same parameters 0 and 1, plus 2 and 3, are given entirely different
meanings in draw_arb2.cpp while light interactions are being drawn.
This function is called again before currentRender size is needed by post processing
effects are done, so there's no clash.
// TODO: I'm using 4 for gamma in shaders, so the following shit must be incremented by 1
Only parameters 0..3 were in use before #3877 - and in dhewm3 also 4, for gamma in shader.
Now I've used a new parameter 5 for the size of _currentDepth. It's needed throughout,
including by light interactions, and its size might in theory differ from _currentRender.
Parameters 6 and 7 are used by soft particles #3878. Note these can be freely reused by different draw calls.
==================
*/
void RB_SetProgramEnvironment( bool isPostProcess ) {
	float	parm[4];
	int		pot;

	if ( !glConfig.ARBVertexProgramAvailable ) {
		return;
	}

#if 0
	// screen power of two correction factor, one pixel in so we don't get a bilerp
	// of an uncopied pixel
	int	 w = backEnd.viewDef->viewport.x2 - backEnd.viewDef->viewport.x1 + 1;
	pot = globalImages->currentRenderImage->uploadWidth;
	if ( w == pot ) {
		parm[0] = 1.0;
	} else {
		parm[0] = (float)(w-1) / pot;
	}

	int	 h = backEnd.viewDef->viewport.y2 - backEnd.viewDef->viewport.y1 + 1;
	pot = globalImages->currentRenderImage->uploadHeight;
	if ( h == pot ) {
		parm[1] = 1.0;
	} else {
		parm[1] = (float)(h-1) / pot;
	}

	parm[2] = 0;
	parm[3] = 1;
	qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, 0, parm );
#else
	// screen power of two correction factor, assuming the copy to _currentRender
	// also copied an extra row and column for the bilerp
	int	 w = backEnd.viewDef->viewport.x2 - backEnd.viewDef->viewport.x1 + 1;
	pot = globalImages->currentRenderImage->uploadWidth;
	parm[0] = (float)w / pot;

	int	 h = backEnd.viewDef->viewport.y2 - backEnd.viewDef->viewport.y1 + 1;
	pot = globalImages->currentRenderImage->uploadHeight;
	parm[1] = (float)h / pot;

	parm[2] = 0;
	parm[3] = 1;
	qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, 0, parm );
#endif

	qglProgramEnvParameter4fvARB( GL_FRAGMENT_PROGRAM_ARB, 0, parm );

	// window coord to 0.0 to 1.0 conversion
	parm[0] = 1.0 / w;
	parm[1] = 1.0 / h;
	parm[2] = 0;
	parm[3] = 1;
	qglProgramEnvParameter4fvARB( GL_FRAGMENT_PROGRAM_ARB, 1, parm );

	// DG: brightness and gamma in shader as program.env[4]
	if ( r_gammaInShader.GetBool() ) {
		// program.env[4].xyz are all r_brightness, program.env[4].w is 1.0/r_gamma
		if ( !isPostProcess ) {
			parm[0] = parm[1] = parm[2] = r_brightness.GetFloat();
			parm[3] = 1.0/r_gamma.GetFloat(); // 1.0/gamma so the shader doesn't have to do this calculation
		} else {
			// don't apply gamma/brightness in postprocess passes to avoid applying them twice
			// (setting them to 1.0 makes them no-ops)
			parm[0] = parm[1] = parm[2] = parm[3] = 1.0f;
		}
		qglProgramEnvParameter4fvARB( GL_FRAGMENT_PROGRAM_ARB, PP_GAMMA_BRIGHTNESS, parm );
	}

	// #3877: Allow shaders to access depth buffer. 
	// Two useful ratios are packed into this parm: [0] and [1] hold the x,y multipliers you need to map a screen 
	// coordinate (fragment position) to the depth image: those are simply the reciprocal of the depth 
	// image size, which has been rounded up to a power of two. Slots [3] and [4] hold the ratio of the depth image
	// size to the current render image size. These sizes can differ if the game crops the render viewport temporarily 
	// during post-processing effects. The depth render is smaller during the effect too, but the depth image doesn't 
	// need to be downsized, whereas the current render image does get downsized when it's captured by the game after 
	// the skybox render pass. The ratio is needed to map between the two render images.
	parm[0] = 1.0f / globalImages->currentDepthImage->uploadWidth;
	parm[1] = 1.0f / globalImages->currentDepthImage->uploadHeight;
	parm[2] = static_cast<float>(globalImages->currentRenderImage->uploadWidth) / globalImages->currentDepthImage->uploadWidth;
	parm[3] = static_cast<float>(globalImages->currentRenderImage->uploadHeight) / globalImages->currentDepthImage->uploadHeight;
	qglProgramEnvParameter4fvARB( GL_FRAGMENT_PROGRAM_ARB, PP_CURDEPTH_RECIPR, parm );

	//
	// set eye position in global space
	//
	parm[0] = backEnd.viewDef->renderView.vieworg[0];
	parm[1] = backEnd.viewDef->renderView.vieworg[1];
	parm[2] = backEnd.viewDef->renderView.vieworg[2];
	parm[3] = 1.0;
	qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, 1, parm );
}

/*
==================
RB_SetProgramEnvironmentSpace

Sets variables related to the current space that can be used by all vertex programs
==================
*/
void RB_SetProgramEnvironmentSpace( void ) {
	if ( !glConfig.ARBVertexProgramAvailable ) {
		return;
	}

	const struct viewEntity_s *space = backEnd.currentSpace;
	float	parm[4];

	// set eye position in local space
	R_GlobalPointToLocal( space->modelMatrix, backEnd.viewDef->renderView.vieworg, *(idVec3 *)parm );
	parm[3] = 1.0;
	qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, 5, parm );

	// we need the model matrix without it being combined with the view matrix
	// so we can transform local vectors to global coordinates
	parm[0] = space->modelMatrix[0];
	parm[1] = space->modelMatrix[4];
	parm[2] = space->modelMatrix[8];
	parm[3] = space->modelMatrix[12];
	qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, 6, parm );
	parm[0] = space->modelMatrix[1];
	parm[1] = space->modelMatrix[5];
	parm[2] = space->modelMatrix[9];
	parm[3] = space->modelMatrix[13];
	qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, 7, parm );
	parm[0] = space->modelMatrix[2];
	parm[1] = space->modelMatrix[6];
	parm[2] = space->modelMatrix[10];
	parm[3] = space->modelMatrix[14];
	qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, 8, parm );
}

/*
==================
RB_STD_T_RenderShaderPasses

This is also called for the generated 2D rendering
==================
*/
void RB_STD_T_RenderShaderPasses( const drawSurf_t *surf ) {
	int			stage;
	const idMaterial	*shader;
	const shaderStage_t *pStage;
	const float	*regs;
	float		color[4];
	const srfTriangles_t	*tri;

	tri = surf->geo;
	shader = surf->material;

	if ( !shader->HasAmbient() ) {
		return;
	}

	if ( shader->IsPortalSky() ) {
		return;
	}

	// change the matrix if needed
	if ( surf->space != backEnd.currentSpace ) {
		qglLoadMatrixf( surf->space->modelViewMatrix );
		backEnd.currentSpace = surf->space;
		RB_SetProgramEnvironmentSpace();
	}

	// change the scissor if needed
	if ( r_useScissor.GetBool() && !backEnd.currentScissor.Equals( surf->scissorRect ) ) {
		backEnd.currentScissor = surf->scissorRect;
		qglScissor( backEnd.viewDef->viewport.x1 + backEnd.currentScissor.x1,
			backEnd.viewDef->viewport.y1 + backEnd.currentScissor.y1,
			backEnd.currentScissor.x2 + 1 - backEnd.currentScissor.x1,
			backEnd.currentScissor.y2 + 1 - backEnd.currentScissor.y1 );
	}

	// some deforms may disable themselves by setting numIndexes = 0
	if ( !tri->numIndexes ) {
		return;
	}

	if ( !tri->ambientCache ) {
		common->Printf( "RB_T_RenderShaderPasses: !tri->ambientCache\n" );
		return;
	}

	// check whether we're drawing a soft particle surface #3878
	const bool soft_particle = ( surf->dsFlags & DSF_SOFT_PARTICLE ) != 0;
	
	// get the expressions for conditionals / color / texcoords
	regs = surf->shaderRegisters;

	// set face culling appropriately
	GL_Cull( shader->GetCullType() );

	// set polygon offset if necessary
	if ( shader->TestMaterialFlag(MF_POLYGONOFFSET) ) {
		qglEnable( GL_POLYGON_OFFSET_FILL );
		qglPolygonOffset( r_offsetFactor.GetFloat(), r_offsetUnits.GetFloat() * shader->GetPolygonOffset() );
	}

	if ( surf->space->weaponDepthHack ) {
		RB_EnterWeaponDepthHack();
	}

	if ( surf->space->modelDepthHack != 0.0f && !soft_particle ) // #3878 soft particles don't want modelDepthHack, which is
	{                                                            // an older way to slightly "soften" particles
		RB_EnterModelDepthHack( surf->space->modelDepthHack );
	}

	idDrawVert *ac = (idDrawVert *)vertexCache.Position( tri->ambientCache );
	qglVertexPointer( 3, GL_FLOAT, sizeof( idDrawVert ), ac->xyz.ToFloatPtr() );
	qglTexCoordPointer( 2, GL_FLOAT, sizeof( idDrawVert ), reinterpret_cast<void *>(&ac->st) );

	for ( stage = 0; stage < shader->GetNumStages() ; stage++ ) {
		pStage = shader->GetStage(stage);

		// check the enable condition
		if ( regs[ pStage->conditionRegister ] == 0 ) {
			continue;
		}

		// skip the stages involved in lighting
		if ( pStage->lighting != SL_AMBIENT ) {
			continue;
		}

		// skip if the stage is ( GL_ZERO, GL_ONE ), which is used for some alpha masks
		if ( ( pStage->drawStateBits & (GLS_SRCBLEND_BITS|GLS_DSTBLEND_BITS) ) == ( GLS_SRCBLEND_ZERO | GLS_DSTBLEND_ONE ) ) {
			continue;
		}

		// determine the blend mode (used by soft particles #3878)
		const int src_blend = pStage->drawStateBits & GLS_SRCBLEND_BITS;

		// see if we are a new-style stage
		newShaderStage_t *newStage = pStage->newStage;
		if ( newStage ) {
			//--------------------------
			//
			// new style stages
			//
			//--------------------------

			// completely skip the stage if we don't have the capability
			if ( tr.backEndRenderer != BE_ARB2 ) {
				continue;
			}
			if ( r_skipNewAmbient.GetBool() ) {
				continue;
			}
			qglColorPointer( 4, GL_UNSIGNED_BYTE, sizeof( idDrawVert ), (void *)&ac->color );
			qglVertexAttribPointerARB( 9, 3, GL_FLOAT, false, sizeof( idDrawVert ), ac->tangents[0].ToFloatPtr() );
			qglVertexAttribPointerARB( 10, 3, GL_FLOAT, false, sizeof( idDrawVert ), ac->tangents[1].ToFloatPtr() );
			qglNormalPointer( GL_FLOAT, sizeof( idDrawVert ), ac->normal.ToFloatPtr() );

			qglEnableClientState( GL_COLOR_ARRAY );
			qglEnableVertexAttribArrayARB( 9 );
			qglEnableVertexAttribArrayARB( 10 );
			qglEnableClientState( GL_NORMAL_ARRAY );

			GL_State( pStage->drawStateBits );

			qglBindProgramARB( GL_VERTEX_PROGRAM_ARB, newStage->vertexProgram );
			qglEnable( GL_VERTEX_PROGRAM_ARB );

			// megaTextures bind a lot of images and set a lot of parameters
			if ( newStage->megaTexture ) {
				newStage->megaTexture->SetMappingForSurface( tri );
				idVec3	localViewer;
				R_GlobalPointToLocal( surf->space->modelMatrix, backEnd.viewDef->renderView.vieworg, localViewer );
				newStage->megaTexture->BindForViewOrigin( localViewer );
			}

			for ( int i = 0 ; i < newStage->numVertexParms ; i++ ) {
				float	parm[4];
				parm[0] = regs[ newStage->vertexParms[i][0] ];
				parm[1] = regs[ newStage->vertexParms[i][1] ];
				parm[2] = regs[ newStage->vertexParms[i][2] ];
				parm[3] = regs[ newStage->vertexParms[i][3] ];
				qglProgramLocalParameter4fvARB( GL_VERTEX_PROGRAM_ARB, i, parm );
			}

			for ( int i = 0 ; i < newStage->numFragmentProgramImages ; i++ ) {
				if ( newStage->fragmentProgramImages[i] ) {
					GL_SelectTexture( i );
					newStage->fragmentProgramImages[i]->Bind();
				}
			}
			qglBindProgramARB( GL_FRAGMENT_PROGRAM_ARB, newStage->fragmentProgram );
			qglEnable( GL_FRAGMENT_PROGRAM_ARB );

			// draw it
			RB_DrawElementsWithCounters( tri );

			for ( int i = 1 ; i < newStage->numFragmentProgramImages ; i++ ) {
				if ( newStage->fragmentProgramImages[i] ) {
					GL_SelectTexture( i );
					globalImages->BindNull();
				}
			}
			if ( newStage->megaTexture ) {
				newStage->megaTexture->Unbind();
			}

			GL_SelectTexture( 0 );

			qglDisable( GL_VERTEX_PROGRAM_ARB );
			qglDisable( GL_FRAGMENT_PROGRAM_ARB );
			// Fixme: Hack to get around an apparent bug in ATI drivers.  Should remove as soon as it gets fixed.
			qglBindProgramARB( GL_VERTEX_PROGRAM_ARB, 0 ); // FIXME: ...

			qglDisableClientState( GL_COLOR_ARRAY );
			qglDisableVertexAttribArrayARB( 9 );
			qglDisableVertexAttribArrayARB( 10 );
			qglDisableClientState( GL_NORMAL_ARRAY );
			continue;
		}
		else if ( soft_particle 
				 && surf->particle_radius > 0.0f 
				 && ( src_blend == GLS_SRCBLEND_ONE || src_blend == GLS_SRCBLEND_SRC_ALPHA ) 
				 && tr.backEndRenderer == BE_ARB2
				 && !r_skipNewAmbient.GetBool() )
		{
			// SteveL #3878. Particles are automatically softened by the engine, unless they have shader programs of 
			// their own (i.e. are "newstages" handled above). This section comes after the newstage part so that if a
			// designer has specified their own shader programs, those will be used instead of the soft particle program.
			if ( pStage->vertexColor == SVC_IGNORE )
			{
				// Ignoring vertexColor is not recommended for particles. The particle system uses vertexColor for fading.
				// However, there are existing particle effects that don't use it, in which case we default to using the 
				// rgb color modulation specified in the material like the "old stages" do below. 
				color[0] = regs[pStage->color.registers[0]];
				color[1] = regs[pStage->color.registers[1]];
				color[2] = regs[pStage->color.registers[2]];
				color[3] = regs[pStage->color.registers[3]];
				qglColor4fv( color );
			}
			else
			{
				// A properly set-up particle shader
				qglColorPointer( 4, GL_UNSIGNED_BYTE, sizeof( idDrawVert ), (void *)&ac->color );
				qglEnableClientState( GL_COLOR_ARRAY );
			}

#if 0 // debug stuff: render particles opaque so debug colors written in the shader are properly visible
			int dsbits = pStage->drawStateBits | GLS_DEPTHFUNC_ALWAYS;
			dsbits &= ~(GLS_SRCBLEND_BITS | GLS_DSTBLEND_BITS);
			//dsbits |= GLS_SRCBLEND_ONE | GLS_DSTBLEND_ZERO; both values are 0, so this would be a noop
			GL_State( dsbits );
#endif
			GL_State( pStage->drawStateBits | GLS_DEPTHFUNC_ALWAYS ); // Disable depth clipping. The fragment program will
																	  // handle it to allow overdraw.

			qglBindProgramARB( GL_VERTEX_PROGRAM_ARB, VPROG_SOFT_PARTICLE );
			qglEnable( GL_VERTEX_PROGRAM_ARB );

			// Bind image and _currentDepth
			GL_SelectTexture( 0 );
			pStage->texture.image->Bind();
			GL_SelectTexture( 1 );
			globalImages->currentDepthImage->Bind();

			qglBindProgramARB( GL_FRAGMENT_PROGRAM_ARB, FPROG_SOFT_PARTICLE );
			qglEnable( GL_FRAGMENT_PROGRAM_ARB );

#if 0 // debug stuff
			// Set up parameters for fragment program
			const char* srcblendstr = "???";
			if ( src_blend >= 0 && src_blend <= 9 ) {
				const char* blendModes[] = {
					"ONE",
					"ZERO",
					"!! INVALID !!",
					"DST_COLOR",
					"ONE_MINUS_DST_COLOR",
					"SRC_ALPHA",
					"ONE_MINUS_SRC_ALPHA",
					"DST_ALPHA",
					"ONE_MINUS_DST_ALPHA",
					"ALPHA_SATURATE"
				};
				srcblendstr = blendModes[src_blend];
			}
			

			int dst_blend = pStage->drawStateBits & GLS_DSTBLEND_BITS;
			const char* dstblend = "???";
			switch ( dst_blend ) {
#define MY_CASE(X)  case GLS_DSTBLEND_ ##X : dstblend = #X; break;
				MY_CASE(ZERO)
				MY_CASE(ONE)
				MY_CASE(SRC_COLOR)
				MY_CASE(ONE_MINUS_SRC_COLOR)
				MY_CASE(SRC_ALPHA)
				MY_CASE(ONE_MINUS_SRC_ALPHA)
				MY_CASE(DST_ALPHA)
				MY_CASE(ONE_MINUS_DST_ALPHA)
#undef MY_CASE
			}

			printf("XX mat: %s, src_blend = %s dest_blend = %s radius = %g\n", shader->GetName(), srcblendstr, dstblend, surf->particle_radius);
#endif

			// program.env[23] is the particle radius, given as { radius, 1/(faderange), 1/radius }
			float fadeRange = 1.0f;
			// fadeRange is the particle diameter for alpha blends (like smoke), but the particle radius for additive
			// blends (light glares), because additive effects work differently. Fog is half as apparent when a wall
			// is in the middle of it. Light glares lose no visibility when they have something to reflect off. See 
			// The Dark Mod issue #3878 for diagram
			if ( src_blend == GLS_SRCBLEND_SRC_ALPHA ) // an alpha blend material
			{
				fadeRange = surf->particle_radius * 2.0f;
			}
			else if ( src_blend == GLS_SRCBLEND_ONE ) // an additive (blend add) material
			{
				fadeRange = surf->particle_radius;
			}

			float parm[4] = {
				surf->particle_radius,
				1.0f / ( fadeRange ),
				1.0f / surf->particle_radius,
				0.0f
			};
			qglProgramEnvParameter4fvARB( GL_FRAGMENT_PROGRAM_ARB, PP_PARTICLE_RADIUS, parm );

			// program.env[24] is the color channel mask. It gets added to the fade multiplier, so adding 1
			//    to a channel will make sure it doesn't get faded at all. Particles with additive blend 
			//    need their RGB channels modifying to blend them out. Particles with an alpha blend need 
			//    their alpha channel modifying.
			if ( src_blend == GLS_SRCBLEND_SRC_ALPHA ) // an alpha blend material
			{
				parm[0] = parm[1] = parm[2] = 1.0f; // Leave the rgb channels at full strength when fading
				parm[3] = 0.0f;						// but fade the alpha channel
			}
			else if ( src_blend == GLS_SRCBLEND_ONE ) // an additive (blend add) material
			{
				parm[0] = parm[1] = parm[2] = 0.0f; // Fade the rgb channels but
				parm[3] = 1.0f;						// leave the alpha channel at full strength
			}
			qglProgramEnvParameter4fvARB( GL_FRAGMENT_PROGRAM_ARB, PP_PARTICLE_COLCHAN_MASK, parm );
			
			// draw it
			RB_DrawElementsWithCounters( tri );

			// Clean up GL state
			GL_SelectTexture( 1 );
			globalImages->BindNull();
			GL_SelectTexture( 0 );
			globalImages->BindNull();
			
			qglDisable( GL_VERTEX_PROGRAM_ARB );
			qglDisable( GL_FRAGMENT_PROGRAM_ARB );

			if ( pStage->vertexColor != SVC_IGNORE ) {
				qglDisableClientState( GL_COLOR_ARRAY );
			}
			continue;
		}

		//--------------------------
		//
		// old style stages
		//
		//--------------------------

		// set the color
		color[0] = regs[ pStage->color.registers[0] ];
		color[1] = regs[ pStage->color.registers[1] ];
		color[2] = regs[ pStage->color.registers[2] ];
		color[3] = regs[ pStage->color.registers[3] ];

		// skip the entire stage if an add would be black
		if ( ( pStage->drawStateBits & (GLS_SRCBLEND_BITS|GLS_DSTBLEND_BITS) ) == ( GLS_SRCBLEND_ONE | GLS_DSTBLEND_ONE )
			&& color[0] <= 0 && color[1] <= 0 && color[2] <= 0 ) {
			continue;
		}

		// skip the entire stage if a blend would be completely transparent
		if ( ( pStage->drawStateBits & (GLS_SRCBLEND_BITS|GLS_DSTBLEND_BITS) ) == ( GLS_SRCBLEND_SRC_ALPHA | GLS_DSTBLEND_ONE_MINUS_SRC_ALPHA )
			&& color[3] <= 0 ) {
			continue;
		}

		// select the vertex color source
		if ( pStage->vertexColor == SVC_IGNORE ) {
			qglColor4fv( color );
		} else {
			qglColorPointer( 4, GL_UNSIGNED_BYTE, sizeof( idDrawVert ), (void *)&ac->color );
			qglEnableClientState( GL_COLOR_ARRAY );

			if ( pStage->vertexColor == SVC_INVERSE_MODULATE ) {
				GL_TexEnv( GL_COMBINE_ARB );
				qglTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_MODULATE );
				qglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
				qglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PRIMARY_COLOR_ARB );
				qglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND0_RGB_ARB, GL_SRC_COLOR );
				qglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND1_RGB_ARB, GL_ONE_MINUS_SRC_COLOR );
				qglTexEnvi( GL_TEXTURE_ENV, GL_RGB_SCALE_ARB, 1 );
			}

			// for vertex color and modulated color, we need to enable a second
			// texture stage
			if ( color[0] != 1 || color[1] != 1 || color[2] != 1 || color[3] != 1 ) {
				GL_SelectTexture( 1 );

				globalImages->whiteImage->Bind();
				GL_TexEnv( GL_COMBINE_ARB );

				qglTexEnvfv( GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, color );

				qglTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_MODULATE );
				qglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_PREVIOUS_ARB );
				qglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_CONSTANT_ARB );
				qglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND0_RGB_ARB, GL_SRC_COLOR );
				qglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND1_RGB_ARB, GL_SRC_COLOR );
				qglTexEnvi( GL_TEXTURE_ENV, GL_RGB_SCALE_ARB, 1 );

				qglTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_MODULATE );
				qglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_PREVIOUS_ARB );
				qglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_ALPHA_ARB, GL_CONSTANT_ARB );
				qglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND0_ALPHA_ARB, GL_SRC_ALPHA );
				qglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND1_ALPHA_ARB, GL_SRC_ALPHA );
				qglTexEnvi( GL_TEXTURE_ENV, GL_ALPHA_SCALE, 1 );

				GL_SelectTexture( 0 );
			}
		}

		// bind the texture
		RB_BindVariableStageImage( &pStage->texture, regs );

		// set the state
		GL_State( pStage->drawStateBits );

		RB_PrepareStageTexturing( pStage, surf, ac );

		// draw it
		RB_DrawElementsWithCounters( tri );

		RB_FinishStageTexturing( pStage, surf, ac );

		if ( pStage->vertexColor != SVC_IGNORE ) {
			qglDisableClientState( GL_COLOR_ARRAY );

			GL_SelectTexture( 1 );
			GL_TexEnv( GL_MODULATE );
			globalImages->BindNull();
			GL_SelectTexture( 0 );
			GL_TexEnv( GL_MODULATE );
		}
	}

	// reset polygon offset
	if ( shader->TestMaterialFlag(MF_POLYGONOFFSET) ) {
		qglDisable( GL_POLYGON_OFFSET_FILL );
	}
	if ( surf->space->weaponDepthHack || ( !soft_particle && surf->space->modelDepthHack != 0.0f ) ) // #3878 soft particles
	{
		RB_LeaveDepthHack();
	}
}

/*
=====================
RB_STD_DrawShaderPasses

Draw non-light dependent passes
=====================
*/
int RB_STD_DrawShaderPasses( drawSurf_t **drawSurfs, int numDrawSurfs ) {
	int				i;

	// only obey skipAmbient if we are rendering a view
	if ( backEnd.viewDef->viewEntitys && r_skipAmbient.GetBool() ) {
		return numDrawSurfs;
	}

	bool isPostProcess = false;

	// if we are about to draw the first surface that needs
	// the rendering in a texture, copy it over
	if ( drawSurfs[0]->material->GetSort() >= SS_POST_PROCESS ) {
		if ( r_skipPostProcess.GetBool() ) {
			return 0;
		}
		isPostProcess = true;

		// only dump if in a 3d view
		if ( backEnd.viewDef->viewEntitys && tr.backEndRenderer == BE_ARB2 ) {
			globalImages->currentRenderImage->CopyFramebuffer( backEnd.viewDef->viewport.x1,
				backEnd.viewDef->viewport.y1,  backEnd.viewDef->viewport.x2 -  backEnd.viewDef->viewport.x1 + 1,
				backEnd.viewDef->viewport.y2 -  backEnd.viewDef->viewport.y1 + 1, true );
		}
		backEnd.currentRenderCopied = true;
	}

	GL_SelectTexture( 1 );
	globalImages->BindNull();

	GL_SelectTexture( 0 );
	qglEnableClientState( GL_TEXTURE_COORD_ARRAY );

	RB_SetProgramEnvironment( isPostProcess );

	// we don't use RB_RenderDrawSurfListWithFunction()
	// because we want to defer the matrix load because many
	// surfaces won't draw any ambient passes
	backEnd.currentSpace = NULL;
	for (i = 0  ; i < numDrawSurfs ; i++ ) {
		if ( drawSurfs[i]->material->SuppressInSubview() ) {
			continue;
		}

		if ( backEnd.viewDef->isXraySubview && drawSurfs[i]->space->entityDef ) {
			if ( drawSurfs[i]->space->entityDef->parms.xrayIndex != 2 ) {
				continue;
			}
		}

		// we need to draw the post process shaders after we have drawn the fog lights
		if ( drawSurfs[i]->material->GetSort() >= SS_POST_PROCESS
			&& !backEnd.currentRenderCopied ) {
			break;
		}

		RB_STD_T_RenderShaderPasses( drawSurfs[i] );
	}

	GL_Cull( CT_FRONT_SIDED );
	qglColor3f( 1, 1, 1 );

	return i;
}



/*
==============================================================================

BACK END RENDERING OF STENCIL SHADOWS

==============================================================================
*/

/*
=====================
RB_T_Shadow

the shadow volumes face INSIDE
=====================
*/
static void RB_T_Shadow( const drawSurf_t *surf ) {
	const srfTriangles_t	*tri;

	// set the light position if we are using a vertex program to project the rear surfaces
	if ( tr.backEndRendererHasVertexPrograms && r_useShadowVertexProgram.GetBool()
		&& surf->space != backEnd.currentSpace ) {
		idVec4 localLight;

		R_GlobalPointToLocal( surf->space->modelMatrix, backEnd.vLight->globalLightOrigin, localLight.ToVec3() );
		localLight.w = 0.0f;
		qglProgramEnvParameter4fvARB( GL_VERTEX_PROGRAM_ARB, PP_LIGHT_ORIGIN, localLight.ToFloatPtr() );
	}

	tri = surf->geo;

	if ( !tri->shadowCache ) {
		return;
	}

	qglVertexPointer( 4, GL_FLOAT, sizeof( shadowCache_t ), vertexCache.Position(tri->shadowCache) );

	// we always draw the sil planes, but we may not need to draw the front or rear caps
	int	numIndexes;
	bool external = false;

	if ( !r_useExternalShadows.GetInteger() ) {
		numIndexes = tri->numIndexes;
	} else if ( r_useExternalShadows.GetInteger() == 2 ) { // force to no caps for testing
		numIndexes = tri->numShadowIndexesNoCaps;
	} else if ( !(surf->dsFlags & DSF_VIEW_INSIDE_SHADOW) ) {
		// if we aren't inside the shadow projection, no caps are ever needed needed
		numIndexes = tri->numShadowIndexesNoCaps;
		external = true;
	} else if ( !backEnd.vLight->viewInsideLight && !(surf->geo->shadowCapPlaneBits & SHADOW_CAP_INFINITE) ) {
		// if we are inside the shadow projection, but outside the light, and drawing
		// a non-infinite shadow, we can skip some caps
		if ( backEnd.vLight->viewSeesShadowPlaneBits & surf->geo->shadowCapPlaneBits ) {
			// we can see through a rear cap, so we need to draw it, but we can skip the
			// caps on the actual surface
			numIndexes = tri->numShadowIndexesNoFrontCaps;
		} else {
			// we don't need to draw any caps
			numIndexes = tri->numShadowIndexesNoCaps;
		}
		external = true;
	} else {
		// must draw everything
		numIndexes = tri->numIndexes;
	}

	// set depth bounds
	if( glConfig.depthBoundsTestAvailable && r_useDepthBoundsTest.GetBool() ) {
		qglDepthBoundsEXT( surf->scissorRect.zmin, surf->scissorRect.zmax );
	}

	// debug visualization
	if ( r_showShadows.GetInteger() ) {
		if ( r_showShadows.GetInteger() == 3 ) {
			if ( external ) {
				qglColor3f( 0.1/backEnd.overBright, 1/backEnd.overBright, 0.1/backEnd.overBright );
			} else {
				// these are the surfaces that require the reverse
				qglColor3f( 1/backEnd.overBright, 0.1/backEnd.overBright, 0.1/backEnd.overBright );
			}
		} else {
			// draw different color for turboshadows
			if ( surf->geo->shadowCapPlaneBits & SHADOW_CAP_INFINITE ) {
				if ( numIndexes == tri->numIndexes ) {
					qglColor3f( 1/backEnd.overBright, 0.1/backEnd.overBright, 0.1/backEnd.overBright );
				} else {
					qglColor3f( 1/backEnd.overBright, 0.4/backEnd.overBright, 0.1/backEnd.overBright );
				}
			} else {
				if ( numIndexes == tri->numIndexes ) {
					qglColor3f( 0.1/backEnd.overBright, 1/backEnd.overBright, 0.1/backEnd.overBright );
				} else if ( numIndexes == tri->numShadowIndexesNoFrontCaps ) {
					qglColor3f( 0.1/backEnd.overBright, 1/backEnd.overBright, 0.6/backEnd.overBright );
				} else {
					qglColor3f( 0.6/backEnd.overBright, 1/backEnd.overBright, 0.1/backEnd.overBright );
				}
			}
		}

		qglStencilOp( GL_KEEP, GL_KEEP, GL_KEEP );
		qglDisable( GL_STENCIL_TEST );
		GL_Cull( CT_TWO_SIDED );
		RB_DrawShadowElementsWithCounters( tri, numIndexes );
		GL_Cull( CT_FRONT_SIDED );
		qglEnable( GL_STENCIL_TEST );

		return;
	}

	// DG: that bloody patent on depth-fail stencil shadows has finally expired on 2019-10-13,
	//     so use them (see https://patents.google.com/patent/US6384822B1/en for expiration status)
	bool useStencilOpSeperate = r_useStencilOpSeparate.GetBool() && qglStencilOpSeparate != NULL;
	if( !r_useCarmacksReverse.GetBool() ) {
		if( useStencilOpSeperate ) {
			// not using z-fail, but using qglStencilOpSeparate()
			GLenum firstFace = backEnd.viewDef->isMirror ? GL_FRONT : GL_BACK;
			GLenum secondFace = backEnd.viewDef->isMirror ? GL_BACK : GL_FRONT;
			GL_Cull( CT_TWO_SIDED );
			if ( !external ) {
				qglStencilOpSeparate( firstFace, GL_KEEP, tr.stencilDecr, tr.stencilDecr );
				qglStencilOpSeparate( secondFace, GL_KEEP, tr.stencilIncr, tr.stencilIncr );
				RB_DrawShadowElementsWithCounters( tri, numIndexes );
			}

			qglStencilOpSeparate( firstFace, GL_KEEP, GL_KEEP, tr.stencilIncr );
			qglStencilOpSeparate( secondFace, GL_KEEP, GL_KEEP, tr.stencilDecr );

			RB_DrawShadowElementsWithCounters( tri, numIndexes );

		} else { // DG: this is the original code:
			// patent-free work around
			if ( !external ) {
				// "preload" the stencil buffer with the number of volumes
				// that get clipped by the near or far clip plane
				qglStencilOp( GL_KEEP, tr.stencilDecr, tr.stencilDecr );
				GL_Cull( CT_FRONT_SIDED );
				RB_DrawShadowElementsWithCounters( tri, numIndexes );
				qglStencilOp( GL_KEEP, tr.stencilIncr, tr.stencilIncr );
				GL_Cull( CT_BACK_SIDED );
				RB_DrawShadowElementsWithCounters( tri, numIndexes );
			}

			// traditional depth-pass stencil shadows
			qglStencilOp( GL_KEEP, GL_KEEP, tr.stencilIncr );
			GL_Cull( CT_FRONT_SIDED );
			RB_DrawShadowElementsWithCounters( tri, numIndexes );

			qglStencilOp( GL_KEEP, GL_KEEP, tr.stencilDecr );
			GL_Cull( CT_BACK_SIDED );
			RB_DrawShadowElementsWithCounters( tri, numIndexes );
		}
	} else { // use the formerly patented "Carmack's Reverse" Z-Fail code
		if( useStencilOpSeperate ) {
			// Z-Fail with glStencilOpSeparate() which will reduce draw calls
			GLenum firstFace = backEnd.viewDef->isMirror ? GL_FRONT : GL_BACK;
			GLenum secondFace = backEnd.viewDef->isMirror ? GL_BACK : GL_FRONT;
			if ( !external ) { // z-fail
				qglStencilOpSeparate( firstFace, GL_KEEP, tr.stencilDecr, GL_KEEP );
				qglStencilOpSeparate( secondFace, GL_KEEP, tr.stencilIncr, GL_KEEP );
			} else { // depth-pass
				qglStencilOpSeparate( firstFace, GL_KEEP, GL_KEEP, tr.stencilIncr );
				qglStencilOpSeparate( secondFace, GL_KEEP, GL_KEEP, tr.stencilDecr );
			}
			GL_Cull( CT_TWO_SIDED );
			RB_DrawShadowElementsWithCounters( tri, numIndexes );

		} else { // Z-Fail without glStencilOpSeparate()

			// LEITH: the (formerly patented) "Carmack's Reverse" code

			// depth-fail/Z-Fail stencil shadows
			if ( !external ) {
				qglStencilOp( GL_KEEP, tr.stencilDecr, GL_KEEP );
				GL_Cull( CT_FRONT_SIDED );
				RB_DrawShadowElementsWithCounters( tri, numIndexes );
				qglStencilOp( GL_KEEP, tr.stencilIncr, GL_KEEP );
				GL_Cull( CT_BACK_SIDED );
				RB_DrawShadowElementsWithCounters( tri, numIndexes );
			}
			// traditional depth-pass stencil shadows
			else {
				qglStencilOp( GL_KEEP, GL_KEEP, tr.stencilIncr );
				GL_Cull( CT_FRONT_SIDED );
				RB_DrawShadowElementsWithCounters( tri, numIndexes );

				qglStencilOp( GL_KEEP, GL_KEEP, tr.stencilDecr );
				GL_Cull( CT_BACK_SIDED );
				RB_DrawShadowElementsWithCounters( tri, numIndexes );
			}
		}
	}
}

/*
=====================
RB_StencilShadowPass

Stencil test should already be enabled, and the stencil buffer should have
been set to 128 on any surfaces that might receive shadows
=====================
*/
void RB_StencilShadowPass( const drawSurf_t *drawSurfs ) {
	if ( !r_shadows.GetBool() ) {
		return;
	}

	if ( !drawSurfs ) {
		return;
	}

	globalImages->BindNull();
	qglDisableClientState( GL_TEXTURE_COORD_ARRAY );

	// for visualizing the shadows
	if ( r_showShadows.GetInteger() ) {
		if ( r_showShadows.GetInteger() == 2 ) {
			// draw filled in
			GL_State( GLS_DEPTHMASK | GLS_SRCBLEND_ONE | GLS_DSTBLEND_ONE | GLS_DEPTHFUNC_LESS  );
		} else {
			// draw as lines, filling the depth buffer
			GL_State( GLS_SRCBLEND_ONE | GLS_DSTBLEND_ZERO | GLS_POLYMODE_LINE | GLS_DEPTHFUNC_ALWAYS  );
		}
	} else {
		// don't write to the color buffer, just the stencil buffer
		GL_State( GLS_DEPTHMASK | GLS_COLORMASK | GLS_ALPHAMASK | GLS_DEPTHFUNC_LESS );
	}

	if ( r_shadowPolygonFactor.GetFloat() || r_shadowPolygonOffset.GetFloat() ) {
		qglPolygonOffset( r_shadowPolygonFactor.GetFloat(), -r_shadowPolygonOffset.GetFloat() );
		qglEnable( GL_POLYGON_OFFSET_FILL );
	}

	qglStencilFunc( GL_ALWAYS, 1, 255 );

	if ( glConfig.depthBoundsTestAvailable && r_useDepthBoundsTest.GetBool() ) {
		qglEnable( GL_DEPTH_BOUNDS_TEST_EXT );
	}

	RB_RenderDrawSurfChainWithFunction( drawSurfs, RB_T_Shadow );

	GL_Cull( CT_FRONT_SIDED );

	if ( r_shadowPolygonFactor.GetFloat() || r_shadowPolygonOffset.GetFloat() ) {
		qglDisable( GL_POLYGON_OFFSET_FILL );
	}

	if ( glConfig.depthBoundsTestAvailable && r_useDepthBoundsTest.GetBool() ) {
		qglDisable( GL_DEPTH_BOUNDS_TEST_EXT );
	}

	qglEnableClientState( GL_TEXTURE_COORD_ARRAY );

	qglStencilFunc( GL_GEQUAL, 128, 255 );
	qglStencilOp( GL_KEEP, GL_KEEP, GL_KEEP );
}



/*
=============================================================================================

BLEND LIGHT PROJECTION

=============================================================================================
*/

/*
=====================
RB_T_BlendLight

=====================
*/
static void RB_T_BlendLight( const drawSurf_t *surf ) {
	const srfTriangles_t *tri;

	tri = surf->geo;

	if ( backEnd.currentSpace != surf->space ) {
		idPlane	lightProject[4];
		int		i;

		for ( i = 0 ; i < 4 ; i++ ) {
			R_GlobalPlaneToLocal( surf->space->modelMatrix, backEnd.vLight->lightProject[i], lightProject[i] );
		}

		GL_SelectTexture( 0 );
		qglTexGenfv( GL_S, GL_OBJECT_PLANE, lightProject[0].ToFloatPtr() );
		qglTexGenfv( GL_T, GL_OBJECT_PLANE, lightProject[1].ToFloatPtr() );
		qglTexGenfv( GL_Q, GL_OBJECT_PLANE, lightProject[2].ToFloatPtr() );

		GL_SelectTexture( 1 );
		qglTexGenfv( GL_S, GL_OBJECT_PLANE, lightProject[3].ToFloatPtr() );
	}

	// this gets used for both blend lights and shadow draws
	if ( tri->ambientCache ) {
		idDrawVert	*ac = (idDrawVert *)vertexCache.Position( tri->ambientCache );
		qglVertexPointer( 3, GL_FLOAT, sizeof( idDrawVert ), ac->xyz.ToFloatPtr() );
	} else if ( tri->shadowCache ) {
		shadowCache_t	*sc = (shadowCache_t *)vertexCache.Position( tri->shadowCache );
		qglVertexPointer( 3, GL_FLOAT, sizeof( shadowCache_t ), sc->xyz.ToFloatPtr() );
	}

	RB_DrawElementsWithCounters( tri );
}


/*
=====================
RB_BlendLight

Dual texture together the falloff and projection texture with a blend
mode to the framebuffer, instead of interacting with the surface texture
=====================
*/
static void RB_BlendLight( const drawSurf_t *drawSurfs,  const drawSurf_t *drawSurfs2 ) {
	const idMaterial	*lightShader;
	const shaderStage_t	*stage;
	int					i;
	const float	*regs;

	if ( !drawSurfs ) {
		return;
	}
	if ( r_skipBlendLights.GetBool() ) {
		return;
	}

	lightShader = backEnd.vLight->lightShader;
	regs = backEnd.vLight->shaderRegisters;

	// texture 1 will get the falloff texture
	GL_SelectTexture( 1 );
	qglDisableClientState( GL_TEXTURE_COORD_ARRAY );
	qglEnable( GL_TEXTURE_GEN_S );
	qglTexCoord2f( 0, 0.5 );
	backEnd.vLight->falloffImage->Bind();

	// texture 0 will get the projected texture
	GL_SelectTexture( 0 );
	qglDisableClientState( GL_TEXTURE_COORD_ARRAY );
	qglEnable( GL_TEXTURE_GEN_S );
	qglEnable( GL_TEXTURE_GEN_T );
	qglEnable( GL_TEXTURE_GEN_Q );

	for ( i = 0 ; i < lightShader->GetNumStages() ; i++ ) {
		stage = lightShader->GetStage(i);

		if ( !regs[ stage->conditionRegister ] ) {
			continue;
		}

		GL_State( GLS_DEPTHMASK | stage->drawStateBits | GLS_DEPTHFUNC_EQUAL );

		GL_SelectTexture( 0 );
		stage->texture.image->Bind();

		if ( stage->texture.hasMatrix ) {
			RB_LoadShaderTextureMatrix( regs, &stage->texture );
		}

		// get the modulate values from the light, including alpha, unlike normal lights
		backEnd.lightColor[0] = regs[ stage->color.registers[0] ];
		backEnd.lightColor[1] = regs[ stage->color.registers[1] ];
		backEnd.lightColor[2] = regs[ stage->color.registers[2] ];
		backEnd.lightColor[3] = regs[ stage->color.registers[3] ];
		qglColor4fv( backEnd.lightColor );

		RB_RenderDrawSurfChainWithFunction( drawSurfs, RB_T_BlendLight );
		RB_RenderDrawSurfChainWithFunction( drawSurfs2, RB_T_BlendLight );

		if ( stage->texture.hasMatrix ) {
			GL_SelectTexture( 0 );
			qglMatrixMode( GL_TEXTURE );
			qglLoadIdentity();
			qglMatrixMode( GL_MODELVIEW );
		}
	}

	GL_SelectTexture( 1 );
	qglDisable( GL_TEXTURE_GEN_S );
	globalImages->BindNull();

	GL_SelectTexture( 0 );
	qglDisable( GL_TEXTURE_GEN_S );
	qglDisable( GL_TEXTURE_GEN_T );
	qglDisable( GL_TEXTURE_GEN_Q );
}


//========================================================================

static idPlane	fogPlanes[4];

/*
=====================
RB_T_BasicFog

=====================
*/
static void RB_T_BasicFog( const drawSurf_t *surf ) {
	if ( backEnd.currentSpace != surf->space ) {
		idPlane	local;

		GL_SelectTexture( 0 );

		R_GlobalPlaneToLocal( surf->space->modelMatrix, fogPlanes[0], local );
		local[3] += 0.5;
		qglTexGenfv( GL_S, GL_OBJECT_PLANE, local.ToFloatPtr() );

//		R_GlobalPlaneToLocal( surf->space->modelMatrix, fogPlanes[1], local );
//		local[3] += 0.5;
local[0] = local[1] = local[2] = 0; local[3] = 0.5;
		qglTexGenfv( GL_T, GL_OBJECT_PLANE, local.ToFloatPtr() );

		GL_SelectTexture( 1 );

		// GL_S is constant per viewer
		R_GlobalPlaneToLocal( surf->space->modelMatrix, fogPlanes[2], local );
		local[3] += FOG_ENTER;
		qglTexGenfv( GL_T, GL_OBJECT_PLANE, local.ToFloatPtr() );

		R_GlobalPlaneToLocal( surf->space->modelMatrix, fogPlanes[3], local );
		qglTexGenfv( GL_S, GL_OBJECT_PLANE, local.ToFloatPtr() );
	}

	RB_T_RenderTriangleSurface( surf );
}



/*
==================
RB_FogPass
==================
*/
static void RB_FogPass( const drawSurf_t *drawSurfs,  const drawSurf_t *drawSurfs2 ) {
	const srfTriangles_t*frustumTris;
	drawSurf_t			ds;
	const idMaterial	*lightShader;
	const shaderStage_t	*stage;
	const float			*regs;

	// create a surface for the light frustom triangles, which are oriented drawn side out
	frustumTris = backEnd.vLight->frustumTris;

	// if we ran out of vertex cache memory, skip it
	if ( !frustumTris->ambientCache ) {
		return;
	}
	memset( &ds, 0, sizeof( ds ) );
	ds.space = &backEnd.viewDef->worldSpace;
	ds.geo = frustumTris;
	ds.scissorRect = backEnd.viewDef->scissor;

	// find the current color and density of the fog
	lightShader = backEnd.vLight->lightShader;
	regs = backEnd.vLight->shaderRegisters;
	// assume fog shaders have only a single stage
	stage = lightShader->GetStage(0);

	backEnd.lightColor[0] = regs[ stage->color.registers[0] ];
	backEnd.lightColor[1] = regs[ stage->color.registers[1] ];
	backEnd.lightColor[2] = regs[ stage->color.registers[2] ];
	backEnd.lightColor[3] = regs[ stage->color.registers[3] ];

	qglColor3fv( backEnd.lightColor );

	// calculate the falloff planes
	float	a;

	// if they left the default value on, set a fog distance of 500
	if ( backEnd.lightColor[3] <= 1.0 ) {
		a = -0.5f / DEFAULT_FOG_DISTANCE;
	} else {
		// otherwise, distance = alpha color
		a = -0.5f / backEnd.lightColor[3];
	}

	GL_State( GLS_DEPTHMASK | GLS_SRCBLEND_SRC_ALPHA | GLS_DSTBLEND_ONE_MINUS_SRC_ALPHA | GLS_DEPTHFUNC_EQUAL );

	// texture 0 is the falloff image
	GL_SelectTexture( 0 );
	globalImages->fogImage->Bind();
	//GL_Bind( tr.whiteImage );
	qglDisableClientState( GL_TEXTURE_COORD_ARRAY );
	qglEnable( GL_TEXTURE_GEN_S );
	qglEnable( GL_TEXTURE_GEN_T );
	qglTexCoord2f( 0.5f, 0.5f );		// make sure Q is set

	fogPlanes[0][0] = a * backEnd.viewDef->worldSpace.modelViewMatrix[2];
	fogPlanes[0][1] = a * backEnd.viewDef->worldSpace.modelViewMatrix[6];
	fogPlanes[0][2] = a * backEnd.viewDef->worldSpace.modelViewMatrix[10];
	fogPlanes[0][3] = a * backEnd.viewDef->worldSpace.modelViewMatrix[14];

	fogPlanes[1][0] = a * backEnd.viewDef->worldSpace.modelViewMatrix[0];
	fogPlanes[1][1] = a * backEnd.viewDef->worldSpace.modelViewMatrix[4];
	fogPlanes[1][2] = a * backEnd.viewDef->worldSpace.modelViewMatrix[8];
	fogPlanes[1][3] = a * backEnd.viewDef->worldSpace.modelViewMatrix[12];


	// texture 1 is the entering plane fade correction
	GL_SelectTexture( 1 );
	globalImages->fogEnterImage->Bind();
	qglDisableClientState( GL_TEXTURE_COORD_ARRAY );
	qglEnable( GL_TEXTURE_GEN_S );
	qglEnable( GL_TEXTURE_GEN_T );

	// T will get a texgen for the fade plane, which is always the "top" plane on unrotated lights
	fogPlanes[2][0] = 0.001f * backEnd.vLight->fogPlane[0];
	fogPlanes[2][1] = 0.001f * backEnd.vLight->fogPlane[1];
	fogPlanes[2][2] = 0.001f * backEnd.vLight->fogPlane[2];
	fogPlanes[2][3] = 0.001f * backEnd.vLight->fogPlane[3];

	// S is based on the view origin
	float s = backEnd.viewDef->renderView.vieworg * fogPlanes[2].Normal() + fogPlanes[2][3];

	fogPlanes[3][0] = 0;
	fogPlanes[3][1] = 0;
	fogPlanes[3][2] = 0;
	fogPlanes[3][3] = FOG_ENTER + s;

	qglTexCoord2f( FOG_ENTER + s, FOG_ENTER );


	// draw it
	RB_RenderDrawSurfChainWithFunction( drawSurfs, RB_T_BasicFog );
	RB_RenderDrawSurfChainWithFunction( drawSurfs2, RB_T_BasicFog );

	// the light frustum bounding planes aren't in the depth buffer, so use depthfunc_less instead
	// of depthfunc_equal
	GL_State( GLS_DEPTHMASK | GLS_SRCBLEND_SRC_ALPHA | GLS_DSTBLEND_ONE_MINUS_SRC_ALPHA | GLS_DEPTHFUNC_LESS );
	GL_Cull( CT_BACK_SIDED );
	RB_RenderDrawSurfChainWithFunction( &ds, RB_T_BasicFog );
	GL_Cull( CT_FRONT_SIDED );

	GL_SelectTexture( 1 );
	qglDisable( GL_TEXTURE_GEN_S );
	qglDisable( GL_TEXTURE_GEN_T );
	globalImages->BindNull();

	GL_SelectTexture( 0 );
	qglDisable( GL_TEXTURE_GEN_S );
	qglDisable( GL_TEXTURE_GEN_T );
}


/*
==================
RB_STD_FogAllLights
==================
*/
void RB_STD_FogAllLights( void ) {
	viewLight_t	*vLight;

	if ( r_skipFogLights.GetBool() || r_showOverDraw.GetInteger() != 0
		 || backEnd.viewDef->isXraySubview /* dont fog in xray mode*/
		 ) {
		return;
	}

	qglDisable( GL_STENCIL_TEST );

	for ( vLight = backEnd.viewDef->viewLights ; vLight ; vLight = vLight->next ) {
		backEnd.vLight = vLight;

		if ( !vLight->lightShader->IsFogLight() && !vLight->lightShader->IsBlendLight() ) {
			continue;
		}

#if 0 // _D3XP disabled that
		if ( r_ignore.GetInteger() ) {
			// we use the stencil buffer to guarantee that no pixels will be
			// double fogged, which happens in some areas that are thousands of
			// units from the origin
			backEnd.currentScissor = vLight->scissorRect;
			if ( r_useScissor.GetBool() ) {
				qglScissor( backEnd.viewDef->viewport.x1 + backEnd.currentScissor.x1,
					backEnd.viewDef->viewport.y1 + backEnd.currentScissor.y1,
					backEnd.currentScissor.x2 + 1 - backEnd.currentScissor.x1,
					backEnd.currentScissor.y2 + 1 - backEnd.currentScissor.y1 );
			}
			qglClear( GL_STENCIL_BUFFER_BIT );

			qglEnable( GL_STENCIL_TEST );

			// only pass on the cleared stencil values
			qglStencilFunc( GL_EQUAL, 128, 255 );

			// when we pass the stencil test and depth test and are going to draw,
			// increment the stencil buffer so we don't ever draw on that pixel again
			qglStencilOp( GL_KEEP, GL_KEEP, GL_INCR );
		}
#endif

		if ( vLight->lightShader->IsFogLight() ) {
			RB_FogPass( vLight->globalInteractions, vLight->localInteractions );
		} else if ( vLight->lightShader->IsBlendLight() ) {
			RB_BlendLight( vLight->globalInteractions, vLight->localInteractions );
		}
		qglDisable( GL_STENCIL_TEST );
	}

	qglEnable( GL_STENCIL_TEST );
}

//=========================================================================================

/*
==================
RB_STD_LightScale

Perform extra blending passes to multiply the entire buffer by
a floating point value
==================
*/
void RB_STD_LightScale( void ) {
	float	v, f;

	if ( backEnd.overBright == 1.0f ) {
		return;
	}

	if ( r_skipLightScale.GetBool() ) {
		return;
	}

	// the scissor may be smaller than the viewport for subviews
	if ( r_useScissor.GetBool() ) {
		qglScissor( backEnd.viewDef->viewport.x1 + backEnd.viewDef->scissor.x1,
			backEnd.viewDef->viewport.y1 + backEnd.viewDef->scissor.y1,
			backEnd.viewDef->scissor.x2 - backEnd.viewDef->scissor.x1 + 1,
			backEnd.viewDef->scissor.y2 - backEnd.viewDef->scissor.y1 + 1 );
		backEnd.currentScissor = backEnd.viewDef->scissor;
	}

	// full screen blends
	qglLoadIdentity();
	qglMatrixMode( GL_PROJECTION );
	qglPushMatrix();
	qglLoadIdentity();
	qglOrtho( 0, 1, 0, 1, -1, 1 );

	GL_State( GLS_SRCBLEND_DST_COLOR | GLS_DSTBLEND_SRC_COLOR );
	GL_Cull( CT_TWO_SIDED );	// so mirror views also get it
	globalImages->BindNull();
	qglDisable( GL_DEPTH_TEST );
	qglDisable( GL_STENCIL_TEST );

	v = 1;
	while ( idMath::Fabs( v - backEnd.overBright ) > 0.01 ) {	// a little extra slop
		f = backEnd.overBright / v;
		f /= 2;
		if ( f > 1 ) {
			f = 1;
		}
		qglColor3f( f, f, f );
		v = v * f * 2;

		qglBegin( GL_QUADS );
		qglVertex2f( 0,0 );
		qglVertex2f( 0,1 );
		qglVertex2f( 1,1 );
		qglVertex2f( 1,0 );
		qglEnd();
	}


	qglPopMatrix();
	qglEnable( GL_DEPTH_TEST );
	qglMatrixMode( GL_MODELVIEW );
	GL_Cull( CT_FRONT_SIDED );
}

//=========================================================================================

/*
=============
RB_STD_DrawView

=============
*/
void	RB_STD_DrawView( void ) {
	drawSurf_t	 **drawSurfs;
	int			numDrawSurfs;

	backEnd.depthFunc = GLS_DEPTHFUNC_EQUAL;

	drawSurfs = (drawSurf_t **)&backEnd.viewDef->drawSurfs[0];
	numDrawSurfs = backEnd.viewDef->numDrawSurfs;

	// clear the z buffer, set the projection matrix, etc
	RB_BeginDrawingView();

	// decide how much overbrighting we are going to do
	RB_DetermineLightScale();

	// fill the depth buffer and clear color buffer to black except on
	// subviews
	RB_STD_FillDepthBuffer( drawSurfs, numDrawSurfs );

	// main light renderer
	switch( tr.backEndRenderer ) {
	case BE_ARB2:
		RB_ARB2_DrawInteractions();
		break;
	}

	// disable stencil shadow test
	qglStencilFunc( GL_ALWAYS, 128, 255 );

	// uplight the entire screen to crutch up not having better blending range
	RB_STD_LightScale();

	// now draw any non-light dependent shading passes
	int	processed = RB_STD_DrawShaderPasses( drawSurfs, numDrawSurfs );

	// fob and blend lights
	RB_STD_FogAllLights();

	// now draw any post-processing effects using _currentRender
	if ( processed < numDrawSurfs ) {
		RB_STD_DrawShaderPasses( drawSurfs+processed, numDrawSurfs-processed );
	}

	RB_RenderDebugTools( drawSurfs, numDrawSurfs );

}