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

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/tr_local.h"

frameData_t		*frameData;
backEndState_t	backEnd;

const unsigned int      NUM_FRAME_DATA = 2;
frameData_t             *smpFrameData[NUM_FRAME_DATA];
volatile unsigned int   smpFrame;

/*
======================
RB_SetDefaultGLState

This should initialize all GL state that any part of the entire program
may touch, including the editor.
======================
*/
void RB_SetDefaultGLState( void ) {
	int		i;

	// Clear value for the Depth buffer
	qglClearDepthf(1.0f);

	// make sure our GL state vector is set correctly
	memset( &backEnd.glState, 0, sizeof( backEnd.glState ) );
	backEnd.glState.forceGlState = true;

	// All color channels are used
	qglColorMask( 1, 1, 1, 1 );

	qglEnable( GL_DEPTH_TEST );
	qglEnable( GL_BLEND );
	qglEnable( GL_SCISSOR_TEST );
	qglEnable( GL_CULL_FACE );
	qglDisable( GL_STENCIL_TEST );

	qglDepthMask( GL_TRUE );
	qglDepthFunc( GL_ALWAYS );

	qglCullFace( GL_FRONT_AND_BACK );

	if ( r_useScissor.GetBool() ) {
		qglScissor( 0, 0, glConfig.vidWidth, glConfig.vidHeight );
	}

	backEnd.glState.currentTexture = -1;  // Force texture unit to be reset
	for ( i = glConfig.maxTextureUnits - 1 ; i >= 0 ; i-- ) {
		GL_SelectTexture( i );
		globalImages->BindNull();
	}
	// Last active texture is Tex0
}

/*
====================
GL_SelectTexture
====================
*/
void GL_SelectTexture( int unit ) {
	if ( backEnd.glState.currentTexture != unit ) {
		qglActiveTexture(GL_TEXTURE0 + unit);
		backEnd.glState.currentTexture = unit;
	}
}

/*
====================
GL_Cull

This handles the flipping needed when the view being
rendered is a mirored view.
====================
*/
void GL_Cull( int cullType ) {
	if ( backEnd.glState.faceCulling == cullType ) {
		return;
	}

	if ( cullType == CT_TWO_SIDED ) {
		qglDisable( GL_CULL_FACE );
	} else {
		if ( backEnd.glState.faceCulling == CT_TWO_SIDED ) {
			qglEnable( GL_CULL_FACE );
		}

		if ( cullType == CT_BACK_SIDED ) {
			if ( backEnd.viewDef->isMirror ) {
				qglCullFace( GL_FRONT );
			} else {
				qglCullFace( GL_BACK );
			}
		} else {
			if ( backEnd.viewDef->isMirror ) {
				qglCullFace( GL_BACK );
			} else {
				qglCullFace( GL_FRONT );
			}
		}
	}

	backEnd.glState.faceCulling = cullType;
}

/*
=================
GL_ClearStateDelta

Clears the state delta bits, so the next GL_State
will set every item
=================
*/
void GL_ClearStateDelta( void ) {
	backEnd.glState.forceGlState = true;
}

/*
====================
GL_State

This routine is responsible for setting the most commonly changed state
====================
*/
void GL_State( int stateBits ) {
	int	diff;

	if ( !r_useStateCaching.GetBool() || backEnd.glState.forceGlState ) {
		// make sure everything is set all the time, so we
		// can see if our delta checking is screwing up
		diff = -1;
		backEnd.glState.forceGlState = false;
	} else {
		diff = stateBits ^ backEnd.glState.glStateBits;
		if ( !diff ) {
			return;
		}
	}

	//
	// check depthFunc bits
	//
	if ( diff & ( GLS_DEPTHFUNC_EQUAL | GLS_DEPTHFUNC_LESS | GLS_DEPTHFUNC_ALWAYS ) ) {
		if ( stateBits & GLS_DEPTHFUNC_EQUAL ) {
			qglDepthFunc( GL_EQUAL );
		} else if ( stateBits & GLS_DEPTHFUNC_ALWAYS ) {
			qglDepthFunc( GL_ALWAYS );
		} else {
			qglDepthFunc( GL_LEQUAL );
		}
	}


	//
	// check blend bits
	//
	if ( diff & ( GLS_SRCBLEND_BITS | GLS_DSTBLEND_BITS ) ) {
		GLenum srcFactor, dstFactor;

		switch ( stateBits & GLS_SRCBLEND_BITS ) {
		case GLS_SRCBLEND_ZERO:
			srcFactor = GL_ZERO;
			break;
		case GLS_SRCBLEND_ONE:
			srcFactor = GL_ONE;
			break;
		case GLS_SRCBLEND_DST_COLOR:
			srcFactor = GL_DST_COLOR;
			break;
		case GLS_SRCBLEND_ONE_MINUS_DST_COLOR:
			srcFactor = GL_ONE_MINUS_DST_COLOR;
			break;
		case GLS_SRCBLEND_SRC_ALPHA:
			srcFactor = GL_SRC_ALPHA;
			break;
		case GLS_SRCBLEND_ONE_MINUS_SRC_ALPHA:
			srcFactor = GL_ONE_MINUS_SRC_ALPHA;
			break;
		case GLS_SRCBLEND_DST_ALPHA:
			srcFactor = GL_DST_ALPHA;
			break;
		case GLS_SRCBLEND_ONE_MINUS_DST_ALPHA:
			srcFactor = GL_ONE_MINUS_DST_ALPHA;
			break;
		case GLS_SRCBLEND_ALPHA_SATURATE:
			srcFactor = GL_SRC_ALPHA_SATURATE;
			break;
		default:
			srcFactor = GL_ONE;		// to get warning to shut up
			common->Error( "GL_State: invalid src blend state bits\n" );
			break;
		}

		switch ( stateBits & GLS_DSTBLEND_BITS ) {
		case GLS_DSTBLEND_ZERO:
			dstFactor = GL_ZERO;
			break;
		case GLS_DSTBLEND_ONE:
			dstFactor = GL_ONE;
			break;
		case GLS_DSTBLEND_SRC_COLOR:
			dstFactor = GL_SRC_COLOR;
			break;
		case GLS_DSTBLEND_ONE_MINUS_SRC_COLOR:
			dstFactor = GL_ONE_MINUS_SRC_COLOR;
			break;
		case GLS_DSTBLEND_SRC_ALPHA:
			dstFactor = GL_SRC_ALPHA;
			break;
		case GLS_DSTBLEND_ONE_MINUS_SRC_ALPHA:
			dstFactor = GL_ONE_MINUS_SRC_ALPHA;
			break;
		case GLS_DSTBLEND_DST_ALPHA:
			dstFactor = GL_DST_ALPHA;
			break;
		case GLS_DSTBLEND_ONE_MINUS_DST_ALPHA:
			dstFactor = GL_ONE_MINUS_DST_ALPHA;
			break;
		default:
			dstFactor = GL_ONE;		// to get warning to shut up
			common->Error( "GL_State: invalid dst blend state bits\n" );
			break;
		}

		qglBlendFunc( srcFactor, dstFactor );
	}

	//
	// check depthmask
	//
	if ( diff & GLS_DEPTHMASK ) {
		if ( stateBits & GLS_DEPTHMASK ) {
			qglDepthMask( GL_FALSE );
		} else {
			qglDepthMask( GL_TRUE );
		}
	}

	//
	// check colormask
	//
	if ( diff & (GLS_REDMASK|GLS_GREENMASK|GLS_BLUEMASK|GLS_ALPHAMASK) ) {
		GLboolean		r, g, b, a;
		r = ( stateBits & GLS_REDMASK ) ? 0 : 1;
		g = ( stateBits & GLS_GREENMASK ) ? 0 : 1;
		b = ( stateBits & GLS_BLUEMASK ) ? 0 : 1;
		a = ( stateBits & GLS_ALPHAMASK ) ? 0 : 1;
		qglColorMask( r, g, b, a );
	}

	backEnd.glState.glStateBits = stateBits;
}

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

RENDER BACK END THREAD FUNCTIONS

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

/*
=============
RB_SetBuffer

=============
*/
static void	RB_SetBuffer( const void *data ) {
	const setBufferCommand_t	*cmd;

	// see which draw buffer we want to render the frame to

	cmd = (const setBufferCommand_t *)data;

	backEnd.frameCount = cmd->frameCount;

	// Disabled for OES2
	//qglDrawBuffer( cmd->buffer );

    GLimp_SetupFrame();


    // clear screen for debugging
	// automatically enable this with several other debug tools
	// that might leave unrendered portions of the screen
	if ( r_clear.GetFloat() || idStr::Length( r_clear.GetString() ) != 1 || r_lockSurfaces.GetBool() || r_singleArea.GetBool() ) {
		float c[3];
		if ( sscanf( r_clear.GetString(), "%f %f %f", &c[0], &c[1], &c[2] ) == 3 ) {
			qglClearColor( c[0], c[1], c[2], 1 );
		} else if ( r_clear.GetInteger() == 2 ) {
			qglClearColor( 0.0f, 0.0f,  0.0f, 1.0f );
		} else {
			qglClearColor( 0.4f, 0.0f, 0.25f, 1.0f );
		}
		qglClear( GL_COLOR_BUFFER_BIT );
	}
}

/*
=============
RB_SwapBuffers

=============
*/
const void	RB_SwapBuffers( const void *data ) {

#ifdef WEBGL
	// GAB Note Dec 2018: Clear the Alpha channel, so that final render will not blend with the HTML5 background (canvas with premultiplied alpha)
	qglColorMask(0, 0, 0, 1);
	qglClear(GL_COLOR_BUFFER_BIT);
#endif


	// force a gl sync if requested
	if ( r_finish.GetBool() ) {
		qglFinish();
	}

	// don't flip if drawing to front buffer
	GLimp_SwapBuffers();

}

/*
=============
RB_CopyRender

Copy part of the current framebuffer to an image
=============
*/
const void	RB_CopyRender( const void *data ) {
	const copyRenderCommand_t	*cmd;

	cmd = (const copyRenderCommand_t *)data;

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

	if (cmd->image) {
		cmd->image->CopyFramebuffer( cmd->x, cmd->y, cmd->imageWidth, cmd->imageHeight, false );
	}
}

/*
====================
RB_ExecuteBackEndCommands

This function will be called syncronously if running without
smp extensions, or asyncronously by another thread.
====================
*/
int		backEndStartTime, backEndFinishTime;
void RB_ExecuteBackEndCommands( const emptyCommand_t *cmds ) {
	// r_debugRenderToTexture
	int	c_draw3d = 0, c_draw2d = 0, c_setBuffers = 0, c_swapBuffers = 0, c_copyRenders = 0;

	if ( cmds->commandId == RC_NOP && !cmds->next ) {
		return;
	}

	{
		const emptyCommand_t *cmd = cmds;

		backEndStartTime = Sys_Milliseconds();

		// needed for editor rendering
		RB_SetDefaultGLState();

		for (; cmd; cmd = (const emptyCommand_t *) cmd->next) {
			switch (cmd->commandId) {
				case RC_NOP:
					break;
				case RC_DRAW_VIEW:
					RB_DrawView(cmd);
					if (((const drawSurfsCommand_t *) cmd)->viewDef->viewEntitys) {
						c_draw3d++;
					} else {
						c_draw2d++;
					}
					break;
				case RC_SET_BUFFER:
					RB_SetBuffer(cmd);
					c_setBuffers++;
					break;
				case RC_SWAP_BUFFERS:
					RB_SwapBuffers(cmd);
					c_swapBuffers++;
					break;
				case RC_COPY_RENDER:
					RB_CopyRender(cmd);
					c_copyRenders++;
					break;
				default:
					common->Error("RB_ExecuteBackEndCommands: bad commandId");
					break;
			}
		}
	}

	// stop rendering on this thread
	backEndFinishTime = Sys_Milliseconds();
	backEnd.pc.msec = backEndFinishTime - backEndStartTime;

	if ( r_debugRenderToTexture.GetInteger() == 1 ) {
		common->Printf( "3d: %i, 2d: %i, SetBuf: %i, SwpBuf: %i, CpyRenders: %i, CpyFrameBuf: %i\n", c_draw3d, c_draw2d, c_setBuffers, c_swapBuffers, c_copyRenders, backEnd.c_copyFrameBuffer );
		backEnd.c_copyFrameBuffer = 0;
	}
}