tr_backend.c

3D 游戏界的大牛人 John Carmack 终于放出了 Q3 的源代码

/*
===========================================================================
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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
#include "tr_local.h"

backEndData_t	*backEndData[SMP_FRAMES];
backEndState_t	backEnd;


static 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
};


/*
** GL_Bind
*/
void GL_Bind( image_t *image ) {
	int texnum;

	if ( !image ) {
		ri.Printf( PRINT_WARNING, "GL_Bind: NULL image\n" );
		texnum = tr.defaultImage->texnum;
	} else {
		texnum = image->texnum;
	}

	if ( r_nobind->integer && tr.dlightImage ) {		// performance evaluation option
		texnum = tr.dlightImage->texnum;
	}

	if ( glState.currenttextures[glState.currenttmu] != texnum ) {
		image->frameUsed = tr.frameCount;
		glState.currenttextures[glState.currenttmu] = texnum;
		qglBindTexture (GL_TEXTURE_2D, texnum);
	}
}

/*
** GL_SelectTexture
*/
void GL_SelectTexture( int unit )
{
	if ( glState.currenttmu == unit )
	{
		return;
	}

	if ( unit == 0 )
	{
		qglActiveTextureARB( GL_TEXTURE0_ARB );
		GLimp_LogComment( "glActiveTextureARB( GL_TEXTURE0_ARB )\n" );
		qglClientActiveTextureARB( GL_TEXTURE0_ARB );
		GLimp_LogComment( "glClientActiveTextureARB( GL_TEXTURE0_ARB )\n" );
	}
	else if ( unit == 1 )
	{
		qglActiveTextureARB( GL_TEXTURE1_ARB );
		GLimp_LogComment( "glActiveTextureARB( GL_TEXTURE1_ARB )\n" );
		qglClientActiveTextureARB( GL_TEXTURE1_ARB );
		GLimp_LogComment( "glClientActiveTextureARB( GL_TEXTURE1_ARB )\n" );
	} else {
		ri.Error( ERR_DROP, "GL_SelectTexture: unit = %i", unit );
	}

	glState.currenttmu = unit;
}


/*
** GL_BindMultitexture
*/
void GL_BindMultitexture( image_t *image0, GLuint env0, image_t *image1, GLuint env1 ) {
	int		texnum0, texnum1;

	texnum0 = image0->texnum;
	texnum1 = image1->texnum;

	if ( r_nobind->integer && tr.dlightImage ) {		// performance evaluation option
		texnum0 = texnum1 = tr.dlightImage->texnum;
	}

	if ( glState.currenttextures[1] != texnum1 ) {
		GL_SelectTexture( 1 );
		image1->frameUsed = tr.frameCount;
		glState.currenttextures[1] = texnum1;
		qglBindTexture( GL_TEXTURE_2D, texnum1 );
	}
	if ( glState.currenttextures[0] != texnum0 ) {
		GL_SelectTexture( 0 );
		image0->frameUsed = tr.frameCount;
		glState.currenttextures[0] = texnum0;
		qglBindTexture( GL_TEXTURE_2D, texnum0 );
	}
}


/*
** GL_Cull
*/
void GL_Cull( int cullType ) {
	if ( glState.faceCulling == cullType ) {
		return;
	}

	glState.faceCulling = cullType;

	if ( cullType == CT_TWO_SIDED ) 
	{
		qglDisable( GL_CULL_FACE );
	} 
	else 
	{
		qglEnable( GL_CULL_FACE );

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

/*
** GL_TexEnv
*/
void GL_TexEnv( int env )
{
	if ( env == glState.texEnv[glState.currenttmu] )
	{
		return;
	}

	glState.texEnv[glState.currenttmu] = env;


	switch ( env )
	{
	case GL_MODULATE:
		qglTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
		break;
	case GL_REPLACE:
		qglTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
		break;
	case GL_DECAL:
		qglTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL );
		break;
	case GL_ADD:
		qglTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_ADD );
		break;
	default:
		ri.Error( ERR_DROP, "GL_TexEnv: invalid env '%d' passed\n", env );
		break;
	}
}

/*
** GL_State
**
** This routine is responsible for setting the most commonly changed state
** in Q3.
*/
void GL_State( unsigned long stateBits )
{
	unsigned long diff = stateBits ^ glState.glStateBits;

	if ( !diff )
	{
		return;
	}

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

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

		if ( stateBits & ( GLS_SRCBLEND_BITS | GLS_DSTBLEND_BITS ) )
		{
			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
				ri.Error( ERR_DROP, "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
				ri.Error( ERR_DROP, "GL_State: invalid dst blend state bits\n" );
				break;
			}

			qglEnable( GL_BLEND );
			qglBlendFunc( srcFactor, dstFactor );
		}
		else
		{
			qglDisable( GL_BLEND );
		}
	}

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

	//
	// fill/line mode
	//
	if ( diff & GLS_POLYMODE_LINE )
	{
		if ( stateBits & GLS_POLYMODE_LINE )
		{
			qglPolygonMode( GL_FRONT_AND_BACK, GL_LINE );
		}
		else
		{
			qglPolygonMode( GL_FRONT_AND_BACK, GL_FILL );
		}
	}

	//
	// depthtest
	//
	if ( diff & GLS_DEPTHTEST_DISABLE )
	{
		if ( stateBits & GLS_DEPTHTEST_DISABLE )
		{
			qglDisable( GL_DEPTH_TEST );
		}
		else
		{
			qglEnable( GL_DEPTH_TEST );
		}
	}

	//
	// alpha test
	//
	if ( diff & GLS_ATEST_BITS )
	{
		switch ( stateBits & GLS_ATEST_BITS )
		{
		case 0:
			qglDisable( GL_ALPHA_TEST );
			break;
		case GLS_ATEST_GT_0:
			qglEnable( GL_ALPHA_TEST );
			qglAlphaFunc( GL_GREATER, 0.0f );
			break;
		case GLS_ATEST_LT_80:
			qglEnable( GL_ALPHA_TEST );
			qglAlphaFunc( GL_LESS, 0.5f );
			break;
		case GLS_ATEST_GE_80:
			qglEnable( GL_ALPHA_TEST );
			qglAlphaFunc( GL_GEQUAL, 0.5f );
			break;
		default:
			assert( 0 );
			break;
		}
	}

	glState.glStateBits = stateBits;
}



/*
================
RB_Hyperspace

A player has predicted a teleport, but hasn't arrived yet
================
*/
static void RB_Hyperspace( void ) {
	float		c;

	if ( !backEnd.isHyperspace ) {
		// do initialization shit
	}

	c = ( backEnd.refdef.time & 255 ) / 255.0f;
	qglClearColor( c, c, c, 1 );
	qglClear( GL_COLOR_BUFFER_BIT );

	backEnd.isHyperspace = qtrue;
}


static void SetViewportAndScissor( void ) {
	qglMatrixMode(GL_PROJECTION);
	qglLoadMatrixf( backEnd.viewParms.projectionMatrix );
	qglMatrixMode(GL_MODELVIEW);

	// set the window clipping
	qglViewport( backEnd.viewParms.viewportX, backEnd.viewParms.viewportY, 
		backEnd.viewParms.viewportWidth, backEnd.viewParms.viewportHeight );
	qglScissor( backEnd.viewParms.viewportX, backEnd.viewParms.viewportY, 
		backEnd.viewParms.viewportWidth, backEnd.viewParms.viewportHeight );
}

/*
=================
RB_BeginDrawingView

Any mirrored or portaled views have already been drawn, so prepare
to actually render the visible surfaces for this view
=================
*/
void RB_BeginDrawingView (void) {
	int clearBits = 0;

	// sync with gl if needed
	if ( r_finish->integer == 1 && !glState.finishCalled ) {
		qglFinish ();
		glState.finishCalled = qtrue;
	}
	if ( r_finish->integer == 0 ) {
		glState.finishCalled = qtrue;
	}

	// we will need to change the projection matrix before drawing
	// 2D images again
	backEnd.projection2D = qfalse;

	//
	// set the modelview matrix for the viewer
	//
	SetViewportAndScissor();

	// ensures that depth writes are enabled for the depth clear
	GL_State( GLS_DEFAULT );
	// clear relevant buffers
	clearBits = GL_DEPTH_BUFFER_BIT;

	if ( r_measureOverdraw->integer || r_shadows->integer == 2 )
	{
		clearBits |= GL_STENCIL_BUFFER_BIT;
	}
	if ( r_fastsky->integer && !( backEnd.refdef.rdflags & RDF_NOWORLDMODEL ) )
	{
		clearBits |= GL_COLOR_BUFFER_BIT;	// FIXME: only if sky shaders have been used
#ifdef _DEBUG
		qglClearColor( 0.8f, 0.7f, 0.4f, 1.0f );	// FIXME: get color of sky
#else
		qglClearColor( 0.0f, 0.0f, 0.0f, 1.0f );	// FIXME: get color of sky
#endif
	}
	qglClear( clearBits );

	if ( ( backEnd.refdef.rdflags & RDF_HYPERSPACE ) )
	{
		RB_Hyperspace();
		return;
	}
	else
	{
		backEnd.isHyperspace = qfalse;
	}

	glState.faceCulling = -1;		// force face culling to set next time

	// we will only draw a sun if there was sky rendered in this view
	backEnd.skyRenderedThisView = qfalse;

	// clip to the plane of the portal
	if ( backEnd.viewParms.isPortal ) {
		float	plane[4];
		double	plane2[4];

		plane[0] = backEnd.viewParms.portalPlane.normal[0];
		plane[1] = backEnd.viewParms.portalPlane.normal[1];
		plane[2] = backEnd.viewParms.portalPlane.normal[2];
		plane[3] = backEnd.viewParms.portalPlane.dist;

		plane2[0] = DotProduct (backEnd.viewParms.or.axis[0], plane);
		plane2[1] = DotProduct (backEnd.viewParms.or.axis[1], plane);
		plane2[2] = DotProduct (backEnd.viewParms.or.axis[2], plane);
		plane2[3] = DotProduct (plane, backEnd.viewParms.or.origin) - plane[3];

		qglLoadMatrixf( s_flipMatrix );
		qglClipPlane (GL_CLIP_PLANE0, plane2);
		qglEnable (GL_CLIP_PLANE0);
	} else {
		qglDisable (GL_CLIP_PLANE0);
	}
}


#define	MAC_EVENT_PUMP_MSEC		5

/*
==================
RB_RenderDrawSurfList
==================
*/
void RB_RenderDrawSurfList( drawSurf_t *drawSurfs, int numDrawSurfs ) {
	shader_t		*shader, *oldShader;
	int				fogNum, oldFogNum;
	int				entityNum, oldEntityNum;
	int				dlighted, oldDlighted;
	qboolean		depthRange, oldDepthRange;
	int				i;
	drawSurf_t		*drawSurf;
	int				oldSort;
	float			originalTime;
#ifdef __MACOS__
	int				macEventTime;

	Sys_PumpEvents();		// crutch up the mac's limited buffer queue size

	// we don't want to pump the event loop too often and waste time, so
	// we are going to check every shader change
	macEventTime = ri.Milliseconds() + MAC_EVENT_PUMP_MSEC;
#endif

	// save original time for entity shader offsets
	originalTime = backEnd.refdef.floatTime;

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

	// draw everything
	oldEntityNum = -1;
	backEnd.currentEntity = &tr.worldEntity;
	oldShader = NULL;
	oldFogNum = -1;
	oldDepthRange = qfalse;
	oldDlighted = qfalse;
	oldSort = -1;
	depthRange = qfalse;

	backEnd.pc.c_surfaces += numDrawSurfs;

	for (i = 0, drawSurf = drawSurfs ; i < numDrawSurfs ; i++, drawSurf++) {
		if ( drawSurf->sort == oldSort ) {
			// fast path, same as previous sort
			rb_surfaceTable[ *drawSurf->surface ]( drawSurf->surface );
			continue;
		}
		oldSort = drawSurf->sort;
		R_DecomposeSort( drawSurf->sort, &entityNum, &shader, &fogNum, &dlighted );

		//
		// change the tess parameters if needed
		// a "entityMergable" shader is a shader that can have surfaces from seperate
		// entities merged into a single batch, like smoke and blood puff sprites
		if (shader != oldShader || fogNum != oldFogNum || dlighted != oldDlighted 
			|| ( entityNum != oldEntityNum && !shader->entityMergable ) ) {
			if (oldShader != NULL) {