r_bsp.c

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// FIXME: use bounding-box-based frustum clipping info?

	psurf = &pmodel->surfaces[pmodel->firstmodelsurface];
	numsurfaces = pmodel->nummodelsurfaces;
	pedges = pmodel->edges;

	for (i=0 ; i<numsurfaces ; i++, psurf++)
	{
	// find which side of the node we are on
		pplane = psurf->plane;

		dot = DotProduct (modelorg, pplane->normal) - pplane->dist;

	// draw the polygon
		if (((psurf->flags & SURF_PLANEBACK) && (dot < -BACKFACE_EPSILON)) ||
			(!(psurf->flags & SURF_PLANEBACK) && (dot > BACKFACE_EPSILON)))
		{
		// FIXME: use bounding-box-based frustum clipping info?

		// copy the edges to bedges, flipping if necessary so always
		// clockwise winding
		// FIXME: if edges and vertices get caches, these assignments must move
		// outside the loop, and overflow checking must be done here
			pbverts = bverts;
			pbedges = bedges;
			numbverts = numbedges = 0;

			if (psurf->numedges > 0)
			{
				pbedge = &bedges[numbedges];
				numbedges += psurf->numedges;

				for (j=0 ; j<psurf->numedges ; j++)
				{
				   lindex = pmodel->surfedges[psurf->firstedge+j];

					if (lindex > 0)
					{
						pedge = &pedges[lindex];
						pbedge[j].v[0] = &r_pcurrentvertbase[pedge->v[0]];
						pbedge[j].v[1] = &r_pcurrentvertbase[pedge->v[1]];
					}
					else
					{
						lindex = -lindex;
						pedge = &pedges[lindex];
						pbedge[j].v[0] = &r_pcurrentvertbase[pedge->v[1]];
						pbedge[j].v[1] = &r_pcurrentvertbase[pedge->v[0]];
					}

					pbedge[j].pnext = &pbedge[j+1];
				}

				pbedge[j-1].pnext = NULL;	// mark end of edges

				R_RecursiveClipBPoly (pbedge, currententity->topnode, psurf);
			}
			else
			{
				Sys_Error ("no edges in bmodel");
			}
		}
	}
}


/*
================
R_DrawSubmodelPolygons
================
*/
void R_DrawSubmodelPolygons (model_t *pmodel, int clipflags)
{
	int			i;
	vec_t		dot;
	msurface_t	*psurf;
	int			numsurfaces;
	mplane_t	*pplane;

// FIXME: use bounding-box-based frustum clipping info?

	psurf = &pmodel->surfaces[pmodel->firstmodelsurface];
	numsurfaces = pmodel->nummodelsurfaces;

	for (i=0 ; i<numsurfaces ; i++, psurf++)
	{
	// find which side of the node we are on
		pplane = psurf->plane;

		dot = DotProduct (modelorg, pplane->normal) - pplane->dist;

	// draw the polygon
		if (((psurf->flags & SURF_PLANEBACK) && (dot < -BACKFACE_EPSILON)) ||
			(!(psurf->flags & SURF_PLANEBACK) && (dot > BACKFACE_EPSILON)))
		{
			r_currentkey = ((mleaf_t *)currententity->topnode)->key;

		// FIXME: use bounding-box-based frustum clipping info?
			R_RenderFace (psurf, clipflags);
		}
	}
}


/*
================
R_RecursiveWorldNode
================
*/
void R_RecursiveWorldNode (mnode_t *node, int clipflags)
{
	int			i, c, side, *pindex;
	vec3_t		acceptpt, rejectpt;
	mplane_t	*plane;
	msurface_t	*surf, **mark;
	mleaf_t		*pleaf;
	double		d, dot;

	if (node->contents == CONTENTS_SOLID)
		return;		// solid

	if (node->visframe != r_visframecount)
		return;

// cull the clipping planes if not trivial accept
// FIXME: the compiler is doing a lousy job of optimizing here; it could be
//  twice as fast in ASM
	if (clipflags)
	{
		for (i=0 ; i<4 ; i++)
		{
			if (! (clipflags & (1<<i)) )
				continue;	// don't need to clip against it

		// generate accept and reject points
		// FIXME: do with fast look-ups or integer tests based on the sign bit
		// of the floating point values

			pindex = pfrustum_indexes[i];

			rejectpt[0] = (float)node->minmaxs[pindex[0]];
			rejectpt[1] = (float)node->minmaxs[pindex[1]];
			rejectpt[2] = (float)node->minmaxs[pindex[2]];

			d = DotProduct (rejectpt, view_clipplanes[i].normal);
			d -= view_clipplanes[i].dist;

			if (d <= 0)
				return;

			acceptpt[0] = (float)node->minmaxs[pindex[3+0]];
			acceptpt[1] = (float)node->minmaxs[pindex[3+1]];
			acceptpt[2] = (float)node->minmaxs[pindex[3+2]];

			d = DotProduct (acceptpt, view_clipplanes[i].normal);
			d -= view_clipplanes[i].dist;

			if (d >= 0)
				clipflags &= ~(1<<i);	// node is entirely on screen
		}
	}

// if a leaf node, draw stuff
	if (node->contents < 0)
	{
		pleaf = (mleaf_t *)node;

		mark = pleaf->firstmarksurface;
		c = pleaf->nummarksurfaces;

		if (c)
		{
			do
			{
				(*mark)->visframe = r_framecount;
				mark++;
			} while (--c);
		}

	// deal with model fragments in this leaf
		if (pleaf->efrags)
		{
			R_StoreEfrags (&pleaf->efrags);
		}

		pleaf->key = r_currentkey;
		r_currentkey++;		// all bmodels in a leaf share the same key
	}
	else
	{
	// node is just a decision point, so go down the apropriate sides

	// find which side of the node we are on
		plane = node->plane;

		switch (plane->type)
		{
		case PLANE_X:
			dot = modelorg[0] - plane->dist;
			break;
		case PLANE_Y:
			dot = modelorg[1] - plane->dist;
			break;
		case PLANE_Z:
			dot = modelorg[2] - plane->dist;
			break;
		default:
			dot = DotProduct (modelorg, plane->normal) - plane->dist;
			break;
		}

		if (dot >= 0)
			side = 0;
		else
			side = 1;

	// recurse down the children, front side first
		R_RecursiveWorldNode (node->children[side], clipflags);

	// draw stuff
		c = node->numsurfaces;

		if (c)
		{
			surf = cl.worldmodel->surfaces + node->firstsurface;

			if (dot < -BACKFACE_EPSILON)
			{
				do
				{
					if ((surf->flags & SURF_PLANEBACK) &&
						(surf->visframe == r_framecount))
					{
						if (r_drawpolys)
						{
							if (r_worldpolysbacktofront)
							{
								if (numbtofpolys < MAX_BTOFPOLYS)
								{
									pbtofpolys[numbtofpolys].clipflags =
											clipflags;
									pbtofpolys[numbtofpolys].psurf = surf;
									numbtofpolys++;
								}
							}
							else
							{
								R_RenderPoly (surf, clipflags);
							}
						}
						else
						{
							R_RenderFace (surf, clipflags);
						}
					}

					surf++;
				} while (--c);
			}
			else if (dot > BACKFACE_EPSILON)
			{
				do
				{
					if (!(surf->flags & SURF_PLANEBACK) &&
						(surf->visframe == r_framecount))
					{
						if (r_drawpolys)
						{
							if (r_worldpolysbacktofront)
							{
								if (numbtofpolys < MAX_BTOFPOLYS)
								{
									pbtofpolys[numbtofpolys].clipflags =
											clipflags;
									pbtofpolys[numbtofpolys].psurf = surf;
									numbtofpolys++;
								}
							}
							else
							{
								R_RenderPoly (surf, clipflags);
							}
						}
						else
						{
							R_RenderFace (surf, clipflags);
						}
					}

					surf++;
				} while (--c);
			}

		// all surfaces on the same node share the same sequence number
			r_currentkey++;
		}

	// recurse down the back side
		R_RecursiveWorldNode (node->children[!side], clipflags);
	}
}



/*
================
R_RenderWorld
================
*/
void R_RenderWorld (void)
{
	int			i;
	model_t		*clmodel;
	btofpoly_t	btofpolys[MAX_BTOFPOLYS];

	pbtofpolys = btofpolys;

	currententity = &cl_entities[0];
	VectorCopy (r_origin, modelorg);
	clmodel = currententity->model;
	r_pcurrentvertbase = clmodel->vertexes;

	R_RecursiveWorldNode (clmodel->nodes, 15);

// if the driver wants the polygons back to front, play the visible ones back
// in that order
	if (r_worldpolysbacktofront)
	{
		for (i=numbtofpolys-1 ; i>=0 ; i--)
		{
			R_RenderPoly (btofpolys[i].psurf, btofpolys[i].clipflags);
		}
	}
}