tr_main.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
===========================================================================
*/
// tr_main.c -- main control flow for each frame

#include "tr_local.h"

trGlobals_t		tr;

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
};


refimport_t	ri;

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

/*
=================
R_CullLocalBox

Returns CULL_IN, CULL_CLIP, or CULL_OUT
=================
*/
int R_CullLocalBox (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.or.origin, transformed[i] );
		VectorMA( transformed[i], v[0], tr.or.axis[0], transformed[i] );
		VectorMA( transformed[i], v[1], tr.or.axis[1], transformed[i] );
		VectorMA( transformed[i], v[2], tr.or.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
}

/*
** R_CullLocalPointAndRadius
*/
int R_CullLocalPointAndRadius( vec3_t pt, float radius )
{
	vec3_t transformed;

	R_LocalPointToWorld( pt, transformed );

	return R_CullPointAndRadius( transformed, radius );
}

/*
** R_CullPointAndRadius
*/
int R_CullPointAndRadius( vec3_t pt, float radius )
{
	int		i;
	float	dist;
	cplane_t	*frust;
	qboolean mightBeClipped = qfalse;

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

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

		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
}


/*
=================
R_LocalNormalToWorld

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

/*
=================
R_LocalPointToWorld

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

/*
=================
R_WorldToLocal

=================
*/
void R_WorldToLocal (vec3_t world, vec3_t local) {
	local[0] = DotProduct(world, tr.or.axis[0]);
	local[1] = DotProduct(world, tr.or.axis[1]);
	local[2] = DotProduct(world, tr.or.axis[2]);
}

/*
==========================
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 );
}


/*
==========================
myGlMultMatrix

==========================
*/
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 *or ) {
	float	glMatrix[16];
	vec3_t	delta;
	float	axisLength;

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

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

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

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

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

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

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

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

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

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

/*
=================
R_RotateForViewer

Sets up the modelview matrix for a given viewParm
=================
*/
void R_RotateForViewer (void) 
{
	float	viewerMatrix[16];
	vec3_t	origin;

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

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

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

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

	viewerMatrix[2] = tr.viewParms.or.axis[2][0];
	viewerMatrix[6] = tr.viewParms.or.axis[2][1];
	viewerMatrix[10] = tr.viewParms.or.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.or.modelMatrix );

	tr.viewParms.world = tr.or;

}

/*
** SetFarClip
*/
static void SetFarClip( void )
{
	float	farthestCornerDistance = 0;
	int		i;

	// 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 planes dynamically
	//
	farthestCornerDistance = 0;
	for ( i = 0; i < 8; i++ )
	{
		vec3_t v;
		vec3_t vecTo;
		float distance;

		if ( i & 1 )
		{
			v[0] = tr.viewParms.visBounds[0][0];
		}
		else
		{
			v[0] = tr.viewParms.visBounds[1][0];
		}

		if ( i & 2 )
		{
			v[1] = tr.viewParms.visBounds[0][1];
		}
		else
		{
			v[1] = tr.viewParms.visBounds[1][1];
		}

		if ( i & 4 )
		{
			v[2] = tr.viewParms.visBounds[0][2];
		}
		else
		{
			v[2] = tr.viewParms.visBounds[1][2];
		}

		VectorSubtract( v, tr.viewParms.or.origin, vecTo );

		distance = vecTo[0] * vecTo[0] + vecTo[1] * vecTo[1] + vecTo[2] * vecTo[2];

		if ( distance > farthestCornerDistance )
		{
			farthestCornerDistance = distance;
		}
	}
	tr.viewParms.zFar = sqrt( farthestCornerDistance );
}


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

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

	//
	// set up projection matrix
	//
	zNear	= r_znear->value;
	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;
}

/*
=================
R_SetupFrustum