/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena 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 2 of the License,
or (at your option) any later version.

Quake III Arena 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 Quake III Arena source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
// tr_main.c -- main control flow for each frame

#include "tr_local.h"


trGlobals_t tr;

refimport_t ri;

const float s_flipMatrix[16] = {
	// convert from our coordinate system (looking down X)
	// to OpenGL's coordinate system (looking down -Z)
	0, 0, -1, 0,
	-1, 0, 0, 0,
	0, 1, 0, 0,
	0, 0, 0, 1
};


static void R_LocalPointToWorld( const vec3_t local, vec3_t world )
{
	world[0] = local[0] * tr.orient.axis[0][0] + local[1] * tr.orient.axis[1][0] + local[2] * tr.orient.axis[2][0] + tr.orient.origin[0];
	world[1] = local[0] * tr.orient.axis[0][1] + local[1] * tr.orient.axis[1][1] + local[2] * tr.orient.axis[2][1] + tr.orient.origin[1];
	world[2] = local[0] * tr.orient.axis[0][2] + local[1] * tr.orient.axis[1][2] + local[2] * tr.orient.axis[2][2] + tr.orient.origin[2];
}


static void R_LocalNormalToWorld( const vec3_t local, vec3_t world )
{
	world[0] = local[0] * tr.orient.axis[0][0] + local[1] * tr.orient.axis[1][0] + local[2] * tr.orient.axis[2][0];
	world[1] = local[0] * tr.orient.axis[0][1] + local[1] * tr.orient.axis[1][1] + local[2] * tr.orient.axis[2][1];
	world[2] = local[0] * tr.orient.axis[0][2] + local[1] * tr.orient.axis[1][2] + local[2] * tr.orient.axis[2][2];
}


// returns CULL_IN, CULL_CLIP, or CULL_OUT

int R_CullLocalBox( const vec3_t bounds[2] )
{
	int		i, j;
	vec3_t	transformed[8];
	float	dists[8];
	vec3_t	v;
	cplane_t	*frust;
	int			anyBack;
	int			front, back;

	if ( r_nocull->integer ) {
		return CULL_CLIP;
	}

	// transform into world space
	for (i = 0 ; i < 8 ; i++) {
		v[0] = bounds[i&1][0];
		v[1] = bounds[(i>>1)&1][1];
		v[2] = bounds[(i>>2)&1][2];

		VectorCopy( tr.orient.origin, transformed[i] );
		VectorMA( transformed[i], v[0], tr.orient.axis[0], transformed[i] );
		VectorMA( transformed[i], v[1], tr.orient.axis[1], transformed[i] );
		VectorMA( transformed[i], v[2], tr.orient.axis[2], transformed[i] );
	}

	// check against frustum planes
	anyBack = 0;
	for (i = 0 ; i < 4 ; i++) {
		frust = &tr.viewParms.frustum[i];

		front = back = 0;
		for (j = 0 ; j < 8 ; j++) {
			dists[j] = DotProduct(transformed[j], frust->normal);
			if ( dists[j] > frust->dist ) {
				front = 1;
				if ( back ) {
					break;		// a point is in front
				}
			} else {
				back = 1;
			}
		}
		if ( !front ) {
			// all points were behind one of the planes
			return CULL_OUT;
		}
		anyBack |= back;
	}

	if ( !anyBack ) {
		return CULL_IN;		// completely inside frustum
	}

	return CULL_CLIP;		// partially clipped
}


int R_CullPointAndRadius( const vec3_t pt, float radius )
{
	qbool mightBeClipped = qfalse;

	if ( r_nocull->integer ) {
		return CULL_CLIP;
	}

	// check against frustum planes
	for (int i = 0; i < 4; ++i) 
	{
		const cplane_t* frust = &tr.viewParms.frustum[i];
		float dist = DotProduct( pt, frust->normal) - frust->dist;

		if ( dist < -radius )
		{
			return CULL_OUT;
		}
		else if ( dist <= radius )
		{
			mightBeClipped = qtrue;
		}
	}

	if ( mightBeClipped )
	{
		return CULL_CLIP;
	}

	return CULL_IN;		// completely inside frustum
}


int R_CullLocalPointAndRadius( const vec3_t pt, float radius )
{
	vec3_t transformed;
	R_LocalPointToWorld( pt, transformed );
	return R_CullPointAndRadius( transformed, radius );
}


/*
==========================
R_TransformModelToClip

==========================
*/
void R_TransformModelToClip( const vec3_t src, const float *modelMatrix, const float *projectionMatrix,
							vec4_t eye, vec4_t dst ) {
	int i;

	for ( i = 0 ; i < 4 ; i++ ) {
		eye[i] = 
			src[0] * modelMatrix[ i + 0 * 4 ] +
			src[1] * modelMatrix[ i + 1 * 4 ] +
			src[2] * modelMatrix[ i + 2 * 4 ] +
			1 * modelMatrix[ i + 3 * 4 ];
	}

	for ( i = 0 ; i < 4 ; i++ ) {
		dst[i] = 
			eye[0] * projectionMatrix[ i + 0 * 4 ] +
			eye[1] * projectionMatrix[ i + 1 * 4 ] +
			eye[2] * projectionMatrix[ i + 2 * 4 ] +
			eye[3] * projectionMatrix[ i + 3 * 4 ];
	}
}

/*
==========================
R_TransformClipToWindow

==========================
*/
void R_TransformClipToWindow( const vec4_t clip, const viewParms_t *view, vec4_t normalized, vec4_t window ) {
	normalized[0] = clip[0] / clip[3];
	normalized[1] = clip[1] / clip[3];
	normalized[2] = ( clip[2] + clip[3] ) / ( 2 * clip[3] );

	window[0] = 0.5f * ( 1.0f + normalized[0] ) * view->viewportWidth;
	window[1] = 0.5f * ( 1.0f + normalized[1] ) * view->viewportHeight;
	window[2] = normalized[2];

	window[0] = (int) ( window[0] + 0.5 );
	window[1] = (int) ( window[1] + 0.5 );
}


static void myGlMultMatrix( const float *a, const float *b, float *out )
{
	int		i, j;

	for ( i = 0 ; i < 4 ; i++ ) {
		for ( j = 0 ; j < 4 ; j++ ) {
			out[ i * 4 + j ] =
				a [ i * 4 + 0 ] * b [ 0 * 4 + j ]
				+ a [ i * 4 + 1 ] * b [ 1 * 4 + j ]
				+ a [ i * 4 + 2 ] * b [ 2 * 4 + j ]
				+ a [ i * 4 + 3 ] * b [ 3 * 4 + j ];
		}
	}
}


/*
=================
R_RotateForEntity

Generates an orientation for an entity and viewParms
Does NOT produce any GL calls
Called by both the front end and the back end
=================
*/
void R_RotateForEntity( const trRefEntity_t* ent, const viewParms_t* viewParms, orientationr_t* orient )
{
	float	glMatrix[16];
	vec3_t	delta;
	float	axisLength;

	if ( ent->e.reType != RT_MODEL ) {
		*orient = viewParms->world;
		return;
	}

	VectorCopy( ent->e.origin, orient->origin );

	VectorCopy( ent->e.axis[0], orient->axis[0] );
	VectorCopy( ent->e.axis[1], orient->axis[1] );
	VectorCopy( ent->e.axis[2], orient->axis[2] );

	glMatrix[0] = orient->axis[0][0];
	glMatrix[4] = orient->axis[1][0];
	glMatrix[8] = orient->axis[2][0];
	glMatrix[12] = orient->origin[0];

	glMatrix[1] = orient->axis[0][1];
	glMatrix[5] = orient->axis[1][1];
	glMatrix[9] = orient->axis[2][1];
	glMatrix[13] = orient->origin[1];

	glMatrix[2] = orient->axis[0][2];
	glMatrix[6] = orient->axis[1][2];
	glMatrix[10] = orient->axis[2][2];
	glMatrix[14] = orient->origin[2];

	glMatrix[3] = 0;
	glMatrix[7] = 0;
	glMatrix[11] = 0;
	glMatrix[15] = 1;

	myGlMultMatrix( glMatrix, viewParms->world.modelMatrix, orient->modelMatrix );

	// calculate the viewer origin in the model's space
	// needed for fog, specular, and environment mapping
	VectorSubtract( viewParms->orient.origin, orient->origin, delta );

	// compensate for scale in the axes if necessary
	if ( ent->e.nonNormalizedAxes ) {
		axisLength = VectorLength( ent->e.axis[0] );
		if ( !axisLength ) {
			axisLength = 0;
		} else {
			axisLength = 1.0f / axisLength;
		}
	} else {
		axisLength = 1.0f;
	}

	orient->viewOrigin[0] = DotProduct( delta, orient->axis[0] ) * axisLength;
	orient->viewOrigin[1] = DotProduct( delta, orient->axis[1] ) * axisLength;
	orient->viewOrigin[2] = DotProduct( delta, orient->axis[2] ) * axisLength;
}


// sets up the modelview matrix for a given viewParm

static void R_RotateForViewer()
{
	float	viewerMatrix[16];
	vec3_t	origin;

	Com_Memset( &tr.orient, 0, sizeof(tr.orient) );
	tr.orient.axis[0][0] = 1;
	tr.orient.axis[1][1] = 1;
	tr.orient.axis[2][2] = 1;
	VectorCopy( tr.viewParms.orient.origin, tr.orient.viewOrigin );

	// transform by the camera placement
	VectorCopy( tr.viewParms.orient.origin, origin );

	viewerMatrix[0] = tr.viewParms.orient.axis[0][0];
	viewerMatrix[4] = tr.viewParms.orient.axis[0][1];
	viewerMatrix[8] = tr.viewParms.orient.axis[0][2];
	viewerMatrix[12] = -origin[0] * viewerMatrix[0] + -origin[1] * viewerMatrix[4] + -origin[2] * viewerMatrix[8];

	viewerMatrix[1] = tr.viewParms.orient.axis[1][0];
	viewerMatrix[5] = tr.viewParms.orient.axis[1][1];
	viewerMatrix[9] = tr.viewParms.orient.axis[1][2];
	viewerMatrix[13] = -origin[0] * viewerMatrix[1] + -origin[1] * viewerMatrix[5] + -origin[2] * viewerMatrix[9];

	viewerMatrix[2] = tr.viewParms.orient.axis[2][0];
	viewerMatrix[6] = tr.viewParms.orient.axis[2][1];
	viewerMatrix[10] = tr.viewParms.orient.axis[2][2];
	viewerMatrix[14] = -origin[0] * viewerMatrix[2] + -origin[1] * viewerMatrix[6] + -origin[2] * viewerMatrix[10];

	viewerMatrix[3] = 0;
	viewerMatrix[7] = 0;
	viewerMatrix[11] = 0;
	viewerMatrix[15] = 1;

	// convert from our coordinate system (looking down X)
	// to OpenGL's coordinate system (looking down -Z)
	myGlMultMatrix( viewerMatrix, s_flipMatrix, tr.orient.modelMatrix );

	tr.viewParms.world = tr.orient;
}


static void SetFarClip()
{
	// if not rendering the world (icons, menus, etc)
	// set a 2k far clip plane
	if ( tr.refdef.rdflags & RDF_NOWORLDMODEL ) {
		tr.viewParms.zFar = 2048;
		return;
	}

	// set far clipping plane dynamically

	float farthestCornerDistance = 0;
	for (int i = 0; i < 8; ++i)
	{
		vec3_t v;
		v[0] = (i & 1) ? tr.viewParms.visBounds[0][0] : tr.viewParms.visBounds[1][0];
		v[1] = (i & 2) ? tr.viewParms.visBounds[0][1] : tr.viewParms.visBounds[1][1];
		v[2] = (i & 4) ? tr.viewParms.visBounds[0][2] : tr.viewParms.visBounds[1][2];

		float d = DistanceSquared( v, tr.viewParms.orient.origin );
		if ( d > farthestCornerDistance )
		{
			farthestCornerDistance = d;
		}
	}

	tr.viewParms.zFar = sqrt( farthestCornerDistance );
}


static void R_SetupProjection()
{
	float	xmin, xmax, ymin, ymax;
	float	width, height, depth;
	float	zNear, zFar;

	// dynamically compute far clip plane distance
	SetFarClip();

	//
	// set up projection matrix
	//
	zNear	= 4.0f;
	zFar	= tr.viewParms.zFar;

	ymax = zNear * tan( tr.refdef.fov_y * M_PI / 360.0f );
	ymin = -ymax;

	xmax = zNear * tan( tr.refdef.fov_x * M_PI / 360.0f );
	xmin = -xmax;

	width = xmax - xmin;
	height = ymax - ymin;
	depth = zFar - zNear;

	tr.viewParms.projectionMatrix[0] = 2 * zNear / width;
	tr.viewParms.projectionMatrix[4] = 0;
	tr.viewParms.projectionMatrix[8] = ( xmax + xmin ) / width;	// normally 0
	tr.viewParms.projectionMatrix[12] = 0;

	tr.viewParms.projectionMatrix[1] = 0;
	tr.viewParms.projectionMatrix[5] = 2 * zNear / height;
	tr.viewParms.projectionMatrix[9] = ( ymax + ymin ) / height;	// normally 0
	tr.viewParms.projectionMatrix[13] = 0;

	tr.viewParms.projectionMatrix[2] = 0;
	tr.viewParms.projectionMatrix[6] = 0;
	tr.viewParms.projectionMatrix[10] = -( zFar + zNear ) / depth;
	tr.viewParms.projectionMatrix[14] = -2 * zFar * zNear / depth;

	tr.viewParms.projectionMatrix[3] = 0;
	tr.viewParms.projectionMatrix[7] = 0;
	tr.viewParms.projectionMatrix[11] = -1;
	tr.viewParms.projectionMatrix[15] = 0;
}


// set up the culling frustum planes for the current view

static void R_SetupFrustum()
{
	float	ang, xs, xc;

	ang = tr.viewParms.fovX / 180 * M_PI * 0.5f;
	xs = sin( ang );
	xc = cos( ang );

	VectorScale( tr.viewParms.orient.axis[0], xs, tr.viewParms.frustum[0].normal );
	VectorMA( tr.viewParms.frustum[0].normal, xc, tr.viewParms.orient.axis[1], tr.viewParms.frustum[0].normal );

	VectorScale( tr.viewParms.orient.axis[0], xs, tr.viewParms.frustum[1].normal );
	VectorMA( tr.viewParms.frustum[1].normal, -xc, tr.viewParms.orient.axis[1], tr.viewParms.frustum[1].normal );

	ang = tr.viewParms.fovY / 180 * M_PI * 0.5f;
	xs = sin( ang );
	xc = cos( ang );

	VectorScale( tr.viewParms.orient.axis[0], xs, tr.viewParms.frustum[2].normal );
	VectorMA( tr.viewParms.frustum[2].normal, xc, tr.viewParms.orient.axis[2], tr.viewParms.frustum[2].normal );

	VectorScale( tr.viewParms.orient.axis[0], xs, tr.viewParms.frustum[3].normal );
	VectorMA( tr.viewParms.frustum[3].normal, -xc, tr.viewParms.orient.axis[2], tr.viewParms.frustum[3].normal );

	for (int i = 0; i < 4; ++i) {
		tr.viewParms.frustum[i].type = PLANE_NON_AXIAL;
		tr.viewParms.frustum[i].dist = DotProduct (tr.viewParms.orient.origin, tr.viewParms.frustum[i].normal);
		SetPlaneSignbits( &tr.viewParms.frustum[i] );
	}
}


static void R_MirrorPoint( const vec3_t in, const orientation_t* surface, const orientation_t* camera, vec3_t out )
{
	int		i;
	vec3_t	local;
	vec3_t	transformed;
	float	d;

	VectorSubtract( in, surface->origin, local );

	VectorClear( transformed );
	for ( i = 0 ; i < 3 ; i++ ) {
		d = DotProduct( local, surface->axis[i] );
		VectorMA( transformed, d, camera->axis[i], transformed );
	}

	VectorAdd( transformed, camera->origin, out );
}


static void R_MirrorVector( const vec3_t in, const orientation_t* surface, const orientation_t* camera, vec3_t out )
{
	int		i;
	float	d;

	VectorClear( out );
	for ( i = 0 ; i < 3 ; i++ ) {
		d = DotProduct( in, surface->axis[i] );
		VectorMA( out, d, camera->axis[i], out );
	}
}


static void R_PlaneForSurface( const surfaceType_t* surfType, cplane_t* plane )
{
	vec4_t plane4;

	if (!surfType) {
		Com_Memset( plane, 0, sizeof(*plane) );
		plane->normal[0] = 1;
		return;
	}

	switch (*surfType) {
	case SF_FACE:
		*plane = ((const srfSurfaceFace_t*)surfType)->plane;
		return;

	case SF_TRIANGLES: {
		const srfTriangles_t* tri = (const srfTriangles_t*)surfType;
		const srfVert_t* v1 = tri->verts + tri->indexes[0];
		const srfVert_t* v2 = tri->verts + tri->indexes[1];
		const srfVert_t* v3 = tri->verts + tri->indexes[2];
		PlaneFromPoints( plane4, v1->xyz, v2->xyz, v3->xyz );
		VectorCopy( plane4, plane->normal );
		plane->dist = plane4[3];
	} return;

	case SF_POLY: {
		const srfPoly_t* poly = (const srfPoly_t*)surfType;
		PlaneFromPoints( plane4, poly->verts[0].xyz, poly->verts[1].xyz, poly->verts[2].xyz );
		VectorCopy( plane4, plane->normal );
		plane->dist = plane4[3];
	} return;

	default:
		Com_Memset( plane, 0, sizeof(*plane) );
		plane->normal[0] = 1;
		return;
	}
}

/*
=================
R_GetPortalOrientation

entityNum is the entity that the portal surface is a part of, which may
be moving and rotating.

Returns qtrue if it should be mirrored
=================
*/
qbool R_GetPortalOrientations( drawSurf_t *drawSurf, int entityNum,
							 orientation_t *surface, orientation_t *camera,
							 vec3_t pvsOrigin, qbool *mirror ) {
	int			i;
	cplane_t	originalPlane, plane;
	trRefEntity_t	*e;
	float		d;
	vec3_t		transformed;

	// create plane axis for the portal we are seeing
	R_PlaneForSurface( drawSurf->surface, &originalPlane );

	// rotate the plane if necessary
	if ( entityNum != ENTITYNUM_WORLD ) {
		tr.currentEntityNum = entityNum;
		tr.currentEntity = &tr.refdef.entities[entityNum];

		// get the orientation of the entity
		R_RotateForEntity( tr.currentEntity, &tr.viewParms, &tr.orient );

		// rotate the plane, but keep the non-rotated version for matching
		// against the portalSurface entities
		R_LocalNormalToWorld( originalPlane.normal, plane.normal );
		plane.dist = originalPlane.dist + DotProduct( plane.normal, tr.orient.origin );

		// translate the original plane
		originalPlane.dist = originalPlane.dist + DotProduct( originalPlane.normal, tr.orient.origin );
	} else {
		plane = originalPlane;
	}

	VectorCopy( plane.normal, surface->axis[0] );
	PerpendicularVector( surface->axis[1], surface->axis[0] );
	CrossProduct( surface->axis[0], surface->axis[1], surface->axis[2] );

	// locate the portal entity closest to this plane.
	// origin will be the origin of the portal, origin2 will be
	// the origin of the camera
	for ( i = 0 ; i < tr.refdef.num_entities ; i++ ) {
		e = &tr.refdef.entities[i];
		if ( e->e.reType != RT_PORTALSURFACE ) {
			continue;
		}

		d = DotProduct( e->e.origin, originalPlane.normal ) - originalPlane.dist;
		if ( d > 64 || d < -64) {
			continue;
		}

		// get the pvsOrigin from the entity
		VectorCopy( e->e.oldorigin, pvsOrigin );

		// if the entity is just a mirror, don't use as a camera point
		if ( e->e.oldorigin[0] == e->e.origin[0] && 
			e->e.oldorigin[1] == e->e.origin[1] && 
			e->e.oldorigin[2] == e->e.origin[2] ) {
			VectorScale( plane.normal, plane.dist, surface->origin );
			VectorCopy( surface->origin, camera->origin );
			VectorSubtract( vec3_origin, surface->axis[0], camera->axis[0] );
			VectorCopy( surface->axis[1], camera->axis[1] );
			VectorCopy( surface->axis[2], camera->axis[2] );

			*mirror = qtrue;
			return qtrue;
		}

		// project the origin onto the surface plane to get
		// an origin point we can rotate around
		d = DotProduct( e->e.origin, plane.normal ) - plane.dist;
		VectorMA( e->e.origin, -d, surface->axis[0], surface->origin );

		// now get the camera origin and orientation
		VectorCopy( e->e.oldorigin, camera->origin );
		AxisCopy( e->e.axis, camera->axis );
		VectorSubtract( vec3_origin, camera->axis[0], camera->axis[0] );
		VectorSubtract( vec3_origin, camera->axis[1], camera->axis[1] );

		// optionally rotate
		if ( e->e.oldframe ) {
			// if a speed is specified
			if ( e->e.frame ) {
				// continuous rotate
				d = (tr.refdef.time/1000.0f) * e->e.frame;
				VectorCopy( camera->axis[1], transformed );
				RotatePointAroundVector( camera->axis[1], camera->axis[0], transformed, d );
				CrossProduct( camera->axis[0], camera->axis[1], camera->axis[2] );
			} else {
				// bobbing rotate, with skinNum being the rotation offset
				d = sin( tr.refdef.time * 0.003f );
				d = e->e.skinNum + d * 4;
				VectorCopy( camera->axis[1], transformed );
				RotatePointAroundVector( camera->axis[1], camera->axis[0], transformed, d );
				CrossProduct( camera->axis[0], camera->axis[1], camera->axis[2] );
			}
		}
		else if ( e->e.skinNum ) {
			d = e->e.skinNum;
			VectorCopy( camera->axis[1], transformed );
			RotatePointAroundVector( camera->axis[1], camera->axis[0], transformed, d );
			CrossProduct( camera->axis[0], camera->axis[1], camera->axis[2] );
		}
		*mirror = qfalse;
		return qtrue;
	}

	// if we didn't locate a portal entity, don't render anything.
	// We don't want to just treat it as a mirror, because without a
	// portal entity the server won't have communicated a proper entity set
	// in the snapshot

	// unfortunately, with local movement prediction it is easily possible
	// to see a surface before the server has communicated the matching
	// portal surface entity, so we don't want to print anything here...

	//ri.Printf( PRINT_ALL, "Portal surface without a portal entity\n" );

	return qfalse;
}

static qbool IsMirror( const drawSurf_t *drawSurf, int entityNum )
{
	int			i;
	cplane_t	originalPlane, plane;
	float		d;

	// create plane axis for the portal we are seeing
	R_PlaneForSurface( drawSurf->surface, &originalPlane );

	// rotate the plane if necessary
	if ( entityNum != ENTITYNUM_WORLD )
	{
		tr.currentEntityNum = entityNum;
		tr.currentEntity = &tr.refdef.entities[entityNum];

		// get the orientation of the entity
		R_RotateForEntity( tr.currentEntity, &tr.viewParms, &tr.orient );

		// rotate the plane, but keep the non-rotated version for matching
		// against the portalSurface entities
		R_LocalNormalToWorld( originalPlane.normal, plane.normal );
		plane.dist = originalPlane.dist + DotProduct( plane.normal, tr.orient.origin );

		// translate the original plane
		originalPlane.dist = originalPlane.dist + DotProduct( originalPlane.normal, tr.orient.origin );
	}
	else
	{
		plane = originalPlane;
	}

	// locate the portal entity closest to this plane.
	// origin will be the origin of the portal,
	// oldorigin will be the origin of the camera
	for ( i = 0 ; i < tr.refdef.num_entities ; i++ ) 
	{
		const trRefEntity_t* e = &tr.refdef.entities[i];
		if ( e->e.reType != RT_PORTALSURFACE ) {
			continue;
		}

		d = DotProduct( e->e.origin, originalPlane.normal ) - originalPlane.dist;
		if ( d > 64 || d < -64) {
			continue;
		}

		// if the entity is just a mirror, don't use as a camera point
		return VectorCompare( e->e.origin, e->e.oldorigin );
	}

	return qfalse;
}


// determines if a surface is COMPLETELY offscreen

static qbool SurfIsOffscreen( const drawSurf_t* drawSurf )
{
	float shortest = 100000000;
	int entityNum;
	int numTriangles;
	const shader_t *shader;
	int		fogNum;
	vec4_t clip, eye;
	int i;
	unsigned int pointAnd = (unsigned int)~0;

	R_RotateForViewer();

	R_DecomposeSort( drawSurf->sort, &entityNum, &shader, &fogNum );
	RB_BeginSurface( shader, fogNum );
	rb_surfaceTable[ *drawSurf->surface ]( drawSurf->surface );

	assert( tess.numVertexes < 128 );

	for ( i = 0; i < tess.numVertexes; i++ )
	{
		int j;
		unsigned int pointFlags = 0;

		R_TransformModelToClip( tess.xyz[i], tr.orient.modelMatrix, tr.viewParms.projectionMatrix, eye, clip );

		for ( j = 0; j < 3; j++ )
		{
			if ( clip[j] >= clip[3] )
			{
				pointFlags |= (1 << (j*2));
			}
			else if ( clip[j] <= -clip[3] )
			{
				pointFlags |= ( 1 << (j*2+1));
			}
		}
		pointAnd &= pointFlags;
	}

	// trivially reject
	if ( pointAnd )
	{
		return qtrue;
	}

	// determine if this surface is backfaced and also determine the distance
	// to the nearest vertex so we can cull based on portal range.  Culling
	// based on vertex distance isn't 100% correct (we should be checking for
	// range to the surface), but it's good enough for the types of portals
	// we have in the game right now.
	numTriangles = tess.numIndexes / 3;

	for ( i = 0; i < tess.numIndexes; i += 3 )
	{
		vec3_t normal;
		float dot;
		float len;

		VectorSubtract( tess.xyz[tess.indexes[i]], tr.viewParms.orient.origin, normal );

		len = VectorLengthSquared( normal );			// lose the sqrt
		if ( len < shortest )
		{
			shortest = len;
		}

		if ( ( dot = DotProduct( normal, tess.normal[tess.indexes[i]] ) ) >= 0 )
		{
			numTriangles--;
		}
	}
	if ( !numTriangles )
	{
		return qtrue;
	}

	// mirrors can early out at this point, since we don't do a fade over distance
	// with them (although we could)
	if ( IsMirror( drawSurf, entityNum ) )
	{
		return qfalse;
	}

	if ( shortest > (tess.shader->portalRange*tess.shader->portalRange) )
	{
		return qtrue;
	}

	return qfalse;
}


// returns true if another view has been rendered

static qbool R_MirrorViewBySurface( drawSurf_t* drawSurf, int entityNum )
{
	viewParms_t		newParms;
	viewParms_t		oldParms;
	orientation_t	surface, camera;

	// don't recursively mirror
	if (tr.viewParms.isPortal) {
		ri.Printf( PRINT_DEVELOPER, "WARNING: recursive mirror/portal found\n" );
		return qfalse;
	}

	// r_fastsky's "mindless" blit over the entire screen will destroy portal views
	if ( r_fastsky->integer || r_noportals->integer ) {
		return qfalse;
	}

	// trivially reject portal/mirror
	if ( SurfIsOffscreen( drawSurf ) ) {
		return qfalse;
	}

	// save old viewParms so we can return to it after the mirror view
	oldParms = tr.viewParms;

	newParms = tr.viewParms;
	newParms.isPortal = qtrue;
	if ( !R_GetPortalOrientations( drawSurf, entityNum, &surface, &camera,
			newParms.pvsOrigin, &newParms.isMirror ) ) {
		return qfalse;		// bad portal, no portalentity
	}

	R_MirrorPoint( oldParms.orient.origin, &surface, &camera, newParms.orient.origin );

	VectorSubtract( vec3_origin, camera.axis[0], newParms.portalPlane.normal );
	newParms.portalPlane.dist = DotProduct( camera.origin, newParms.portalPlane.normal );

	R_MirrorVector( oldParms.orient.axis[0], &surface, &camera, newParms.orient.axis[0] );
	R_MirrorVector( oldParms.orient.axis[1], &surface, &camera, newParms.orient.axis[1] );
	R_MirrorVector( oldParms.orient.axis[2], &surface, &camera, newParms.orient.axis[2] );

	// OPTIMIZE: restrict the viewport on the mirrored view

	// render the mirror view
	R_RenderView( &newParms );

	tr.viewParms = oldParms;

	return qtrue;
}


// see if a sprite is inside a fog volume

static int R_SpriteFogNum( const trRefEntity_t* ent )
{
	int i, j;

	if ( tr.refdef.rdflags & RDF_NOWORLDMODEL ) {
		return 0;
	}

	for ( i = 1 ; i < tr.world->numfogs ; i++ ) {
		const fog_t* fog = &tr.world->fogs[i];
		for ( j = 0 ; j < 3 ; j++ ) {
			if ( ent->e.origin[j] - ent->e.radius >= fog->bounds[1][j] ) {
				break;
			}
			if ( ent->e.origin[j] + ent->e.radius <= fog->bounds[0][j] ) {
				break;
			}
		}
		if ( j == 3 ) {
			return i;
		}
	}

	return 0;
}


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

DRAWSURF SORTING

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

/*
===============
R_Radix
===============
*/
static ID_INLINE void R_Radix( int keyByte, int size, drawSurf_t *source, drawSurf_t *dest )
{
  int           count[ 256 ] = { 0 };
  int           index[ 256 ];
  int           i;
  unsigned char *sortKey = NULL;
  unsigned char *end = NULL;

  sortKey = ( (unsigned char *)&source[ 0 ].sort ) + keyByte;
  end = sortKey + ( size * sizeof( drawSurf_t ) );
  for( ; sortKey < end; sortKey += sizeof( drawSurf_t ) )
    ++count[ *sortKey ];

  index[ 0 ] = 0;

  for( i = 1; i < 256; ++i )
    index[ i ] = index[ i - 1 ] + count[ i - 1 ];

  sortKey = ( (unsigned char *)&source[ 0 ].sort ) + keyByte;
  for( i = 0; i < size; ++i, sortKey += sizeof( drawSurf_t ) )
    dest[ index[ *sortKey ]++ ] = source[ i ];
}

/*
===============
R_RadixSort

Radix sort with 4 byte size buckets
===============
*/
static void R_RadixSort( drawSurf_t *source, int size )
{
  static drawSurf_t scratch[ MAX_DRAWSURFS ];
#ifdef Q3_LITTLE_ENDIAN
  R_Radix( 0, size, source, scratch );
  R_Radix( 1, size, scratch, source );
  R_Radix( 2, size, source, scratch );
  R_Radix( 3, size, scratch, source );
#else
  R_Radix( 3, size, source, scratch );
  R_Radix( 2, size, scratch, source );
  R_Radix( 1, size, source, scratch );
  R_Radix( 0, size, scratch, source );
#endif //Q3_LITTLE_ENDIAN
}


// Philip Erdelsky gets all the credit for this one...

static void R_SortLitsurfs( dlight_t* dl )
{
	struct litSurf_tape {
		litSurf_t *first, *last;
		unsigned count;
	} tape[4];

	// distribute the records alternately to tape[0] and tape[1]

	tape[0].count = tape[1].count = 0;
	tape[0].first = tape[1].first = NULL;

	int base = 0;
	litSurf_t* p = dl->head;

	while (p) {
		litSurf_t* next = p->next;
		p->next = tape[base].first;
		tape[base].first = p;
		tape[base].count++;
		p = next;
		base ^= 1;
	}

	// merge from the two active tapes into the two idle ones
	// doubling the number of records and pingponging the tape sets as we go

	unsigned block_size = 1;
	for ( base = 0; tape[base+1].count; base ^= 2, block_size <<= 1 )
	{
		litSurf_tape* tape0 = tape + base;
		litSurf_tape* tape1 = tape + base + 1;
		int dest = base ^ 2;

		tape[dest].count = tape[dest+1].count = 0;
		for (; tape0->count; dest ^= 1)
		{
			litSurf_tape* output_tape = tape + dest;
			unsigned n0, n1;
			n0 = n1 = block_size;

			while (1)
			{
				litSurf_tape* chosen_tape;
				if (n0 == 0 || tape0->count == 0)
				{
					if (n1 == 0 || tape1->count == 0)
						break;
					chosen_tape = tape1;
					n1--;
				}
				else if (n1 == 0 || tape1->count == 0)
				{
					chosen_tape = tape0;
					n0--;
				}
				else if (tape0->first->sort > tape1->first->sort)
				{
					chosen_tape = tape1;
					n1--;
				}
				else
				{
					chosen_tape = tape0;
					n0--;
				}
				chosen_tape->count--;
				p = chosen_tape->first;
				chosen_tape->first = p->next;
				if (output_tape->count == 0)
					output_tape->first = p;
				else
					output_tape->last->next = p;
				output_tape->last = p;
				output_tape->count++;
			}
		}
	}

	if (tape[base].count > 1)
		tape[base].last->next = NULL;

	dl->head = tape[base].first;
}


///////////////////////////////////////////////////////////////


void R_AddDrawSurf( const surfaceType_t* surface, const shader_t* shader, int fogIndex )
{
	// instead of checking for overflow, we just mask the index so it wraps around
	int index = tr.refdef.numDrawSurfs++ & DRAWSURF_MASK;
	// the sort data is packed into a single 32 bit value so it can be
	// compared quickly during the qsorting process
	tr.refdef.drawSurfs[index].sort = (shader->sortedIndex << QSORT_SHADERNUM_SHIFT)
			| tr.shiftedEntityNum | (fogIndex << QSORT_FOGNUM_SHIFT);
	tr.refdef.drawSurfs[index].surface = surface;
}


void R_AddLitSurf( const surfaceType_t* surface, const shader_t* shader, int fogIndex )
{
	tr.pc[RF_LIT_SURFS]++;

	int index = tr.refdef.numLitSurfs++ & DRAWSURF_MASK;
	litSurf_t* litsurf = &tr.refdef.litSurfs[index];

	litsurf->sort = (shader->sortedIndex << QSORT_SHADERNUM_SHIFT)
			| tr.shiftedEntityNum | (fogIndex << QSORT_FOGNUM_SHIFT);
	litsurf->surface = surface;

	if (!tr.light->head)
		tr.light->head = litsurf;
	if (tr.light->tail)
		tr.light->tail->next = litsurf;

	tr.light->tail = litsurf;
	tr.light->tail->next = 0;
}


void R_DecomposeSort( unsigned sort, int *entityNum, const shader_t **shader, int *fogNum )
{
	*fogNum = ( sort >> QSORT_FOGNUM_SHIFT ) & 31;
	*shader = tr.sortedShaders[ ( sort >> QSORT_SHADERNUM_SHIFT ) & (MAX_SHADERS-1) ];
	*entityNum = ( sort >> QSORT_ENTITYNUM_SHIFT ) & MAX_REFENTITIES;
}


static void R_SortDrawSurfs( int firstDrawSurf, int firstLitSurf )
{
	int numDrawSurfs = tr.refdef.numDrawSurfs - firstDrawSurf;
	drawSurf_t* drawSurfs = tr.refdef.drawSurfs + firstDrawSurf;

	const shader_t* shader;
	int		fogNum;
	int		entityNum;
	int		i;

	// it is possible for some views to not have any surfaces
	if ( numDrawSurfs < 1 ) {
		// we still need to add it for hyperspace cases
		R_AddDrawSurfCmd( drawSurfs, 0 );
		return;
	}

	// if we overflowed MAX_DRAWSURFS, the drawsurfs
	// wrapped around in the buffer and we will be missing
	// the first surfaces, not the last ones
	if ( numDrawSurfs > MAX_DRAWSURFS ) {
		numDrawSurfs = MAX_DRAWSURFS;
	}

	// sort the drawsurfs by sort type, then shader, then entity, etc
	R_RadixSort( drawSurfs, numDrawSurfs );

	// check for any pass through drawing, which
	// may cause another view to be rendered first
	for ( i = 0 ; i < numDrawSurfs ; i++ ) {
		R_DecomposeSort( (drawSurfs+i)->sort, &entityNum, &shader, &fogNum );

		if ( shader->sort > SS_PORTAL ) {
			break;
		}

		// no shader should ever have this sort type
		if ( shader->sort == SS_BAD ) {
			ri.Error( ERR_DROP, "Shader '%s' with sort == SS_BAD", shader->name );
		}

		// if the mirror was completely clipped away, we may need to check another surface
		if ( R_MirrorViewBySurface( (drawSurfs+i), entityNum) ) {
			// this is a debug option to see exactly what is being mirrored
			if ( r_portalOnly->integer ) {
				return;
			}
			break;		// only one mirror view at a time
		}
	}

	// all the lit surfaces are in a single queue
	// but each light's surfaces are sorted within its subsection
	for ( i = 0; i < tr.refdef.num_dlights; ++i ) {
		dlight_t* dl = &tr.refdef.dlights[i];
		if (dl->head) {
			R_SortLitsurfs( dl );
		}
	}

	R_AddDrawSurfCmd( drawSurfs, numDrawSurfs );
}


// entities that will have procedurally generated surfaces will just
// point at this for their sorting surface
static const surfaceType_t entitySurface = SF_ENTITY;

static void R_AddEntitySurfaces()
{
	trRefEntity_t* ent;
	const shader_t* shader;

	if ( !r_drawentities->integer )
		return;

	for (tr.currentEntityNum = 0; tr.currentEntityNum < tr.refdef.num_entities; ++tr.currentEntityNum) {
		ent = tr.currentEntity = &tr.refdef.entities[tr.currentEntityNum];

		// preshift the value we are going to OR into the drawsurf sort
		tr.shiftedEntityNum = tr.currentEntityNum << QSORT_ENTITYNUM_SHIFT;

		//
		// the weapon model must be handled special --
		// we don't want the hacked weapon position showing in mirrors,
		// because the true body position will already be drawn
		//
		if ( (ent->e.renderfx & RF_FIRST_PERSON) && tr.viewParms.isPortal ) {
			continue;
		}

		// simple generated models, like sprites and beams, are not culled
		switch ( ent->e.reType ) {
		case RT_PORTALSURFACE:
			break;		// don't draw anything
		case RT_SPRITE:
		case RT_LIGHTNING:
			// self blood sprites, talk balloons, etc should not be drawn in the primary
			// view.  We can't just do this check for all entities, because md3
			// entities may still want to cast shadows from them
			if ( (ent->e.renderfx & RF_THIRD_PERSON) && !tr.viewParms.isPortal ) {
				continue;
			}
			shader = R_GetShaderByHandle( ent->e.customShader );
			R_AddDrawSurf( &entitySurface, shader, R_SpriteFogNum( ent ) );
			break;

		case RT_MODEL:
			// we must set up parts of tr.or for model culling
			R_RotateForEntity( ent, &tr.viewParms, &tr.orient );

			tr.currentModel = R_GetModelByHandle( ent->e.hModel );
			if (!tr.currentModel) {
				R_AddDrawSurf( &entitySurface, tr.defaultShader, 0 );
			} else {
				switch ( tr.currentModel->type ) {
				case MOD_MD3:
					R_AddMD3Surfaces( ent );
					break;
				case MOD_BRUSH:
					R_AddBrushModelSurfaces( ent );
					break;
				case MOD_BAD:		// null model axis
					if ( (ent->e.renderfx & RF_THIRD_PERSON) && !tr.viewParms.isPortal)
						break;
					R_AddDrawSurf( &entitySurface, tr.defaultShader, 0 );
					break;
				default:
					ri.Error( ERR_DROP, "R_AddEntitySurfaces: Bad modeltype" );
					break;
				}
			}
			break;
		default:
			ri.Error( ERR_DROP, "R_AddEntitySurfaces: Bad reType" );
		}
	}
}


static void R_GenerateDrawSurfs()
{
	R_AddWorldSurfaces();

	R_AddPolygonSurfaces();

	// set the projection matrix with the minimum zfar
	// now that we have the world bounded
	// this needs to be done before entities are added,
	// because they use the projection matrix for lod calculation
	R_SetupProjection();

	R_AddEntitySurfaces();
}


static void R_DebugPolygon( int color, int numPoints, const float* points )
{
	int i;

	GL_State( GLS_DEPTHMASK_TRUE | GLS_SRCBLEND_ONE | GLS_DSTBLEND_ONE );

	// draw solid shade
	qglColor3f( color&1, (color>>1)&1, (color>>2)&1 );
	qglBegin( GL_POLYGON );
	for ( i = 0 ; i < numPoints ; i++ ) {
		qglVertex3fv( points + i * 3 );
	}
	qglEnd();

	// draw wireframe outline
	GL_State( GLS_POLYMODE_LINE | GLS_DEPTHMASK_TRUE | GLS_SRCBLEND_ONE | GLS_DSTBLEND_ONE );
	qglDepthRange( 0, 0 );
	qglColor3f( 1, 1, 1 );
	qglBegin( GL_POLYGON );
	for ( i = 0 ; i < numPoints ; i++ ) {
		qglVertex3fv( points + i * 3 );
	}
	qglEnd();
	qglDepthRange( 0, 1 );
}


// visualization aid for movement clipping debugging

static void R_DebugGraphics()
{
	if ( !r_debugSurface->integer )
		return;

	// the render thread can't make callbacks to the main thread
	R_SyncRenderThread();

	GL_Bind( tr.whiteImage);
	GL_Cull( CT_FRONT_SIDED );
	ri.CM_DrawDebugSurface( R_DebugPolygon );
}


int re_cameraMatrixTime;


// a view may be either the actual camera view, or a mirror / remote location

void R_RenderView( const viewParms_t* parms )
{
	if ( parms->viewportWidth <= 0 || parms->viewportHeight <= 0 )
		return;

	tr.viewCount++;

	tr.viewParms = *parms;
	tr.viewParms.frameSceneNum = tr.frameSceneNum;
	tr.viewParms.frameCount = tr.frameCount;

	int firstDrawSurf = tr.refdef.numDrawSurfs;
	int firstLitSurf = tr.refdef.numLitSurfs;

	// set viewParms.world
	re_cameraMatrixTime = Sys_Milliseconds();
	R_RotateForViewer();

	R_SetupFrustum();

	R_GenerateDrawSurfs();

	R_SortDrawSurfs( firstDrawSurf, firstLitSurf );

	// draw main system development information (surface outlines, etc)
	R_DebugGraphics();
}