/*
	gl_rsurf.c

	surface-related refresh code

	Copyright (C) 1996-1997  Id Software, Inc.
	Copyright (C) 2000       Joseph Carter <knghtbrd@debian.org>

	This program 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.

	This program 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 this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

	$Id$
*/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdio.h>
#include <string.h>
#include <math.h>

#include "compat.h"
#include "r_local.h"
#include "qargs.h"
#include "bspfile.h"    // needed by: glquake.h
#include "vid.h"
#include "sys.h"
#include "mathlib.h"    // needed by: protocol.h, render.h, client.h,
                        //  modelgen.h, glmodel.h
#include "wad.h"
#include "draw.h"
#include "cvar.h"
#include "net.h"        // needed by: client.h
#include "protocol.h"   // needed by: client.h
#include "cmd.h"
#include "sbar.h"
#include "render.h"     // needed by: client.h, gl_model.h, glquake.h
#include "client.h"     // need cls in this file
#include "model.h"   // needed by: glquake.h
#include "console.h"
#include "glquake.h"

extern	double	realtime;
int			skytexturenum;

extern vec3_t shadecolor; // Ender (Extend) Colormod
int		lightmap_bytes;		// 1 or 3

int		lightmap_textures;

unsigned		blocklights[18*18*3];

cvar_t		*gl_colorlights;

#define	BLOCK_WIDTH		128
#define	BLOCK_HEIGHT	128

// LordHavoc: since lightmaps are now allocated only as needed, allow a ridiculous number :)
#define	MAX_LIGHTMAPS	1024
int			active_lightmaps;

typedef struct glRect_s {
	unsigned char l,t,w,h;
} glRect_t;

glpoly_t	*lightmap_polys[MAX_LIGHTMAPS];
qboolean	lightmap_modified[MAX_LIGHTMAPS];
glRect_t	lightmap_rectchange[MAX_LIGHTMAPS];

int			allocated[MAX_LIGHTMAPS][BLOCK_WIDTH];

// the lightmap texture data needs to be kept in
// main memory so texsubimage can update properly
// LordHavoc: changed to be allocated at runtime (typically lower memory usage)
byte		*lightmaps[MAX_LIGHTMAPS];

msurface_t  *waterchain = NULL;

extern qboolean lighthalf;

// LordHavoc: place for gl_rsurf setup code
void glrsurf_init()
{
	memset(&lightmaps, 0, sizeof(lightmaps));
}

void recursivelightupdate(mnode_t *node)
{
	int c;
	msurface_t *surf;
	if (node->children[0]->contents >= 0)
		recursivelightupdate(node->children[0]);
	if (node->children[1]->contents >= 0)
		recursivelightupdate(node->children[1]);
	if ((c = node->numsurfaces))
		for (surf = cl.worldmodel->surfaces + node->firstsurface; c ; c--, surf++)
			surf->cached_dlight = true;
}

// LordHavoc: function to force all lightmaps to be updated
void R_ForceLightUpdate()
{
	if (cl.worldmodel && cl.worldmodel->nodes && cl.worldmodel->nodes->contents >= 0)
		recursivelightupdate(cl.worldmodel->nodes);
}

/*
	R_AddDynamicLights

	LordHavoc: completely rewrote this, relies on 64bit integer math...
*/
int dlightdivtable[8192];
int dlightdivtableinitialized = 0;

/*
===============
R_AddDynamicLights
===============
*/
void R_AddDynamicLights (msurface_t *surf)
{
	int			sdtable[18], lnum, td, maxdist, maxdist2, maxdist3, i, s, t, smax, tmax, red, green, blue, j;
	unsigned	*bl;
	float		dist, f;
	vec3_t		impact, local;
	// use 64bit integer...  shame it's not very standardized...
#if _MSC_VER || __BORLANDC__
	__int64		k;
#else
	long long	k;
#endif

	if (!dlightdivtableinitialized)
	{
		dlightdivtable[0] = 1048576 >> 7;
		for (s = 1;s < 8192;s++)
			dlightdivtable[s] = 1048576 / (s << 7);
		dlightdivtableinitialized = 1;
	}

	smax = (surf->extents[0]>>4)+1;
	tmax = (surf->extents[1]>>4)+1;

	for (lnum=0 ; lnum<MAX_DLIGHTS ; lnum++)
	{
		if ( !(surf->dlightbits & (1<<lnum) ) )
			continue;		// not lit by this light

		VectorSubtract(cl_dlights[lnum].origin, currententity->origin, local);
		dist = DotProduct (local, surf->plane->normal) - surf->plane->dist;
		for (i=0 ; i<3 ; i++)
			impact[i] = cl_dlights[lnum].origin[i] - surf->plane->normal[i]*dist;

		f = DotProduct (impact, surf->texinfo->vecs[0]) + surf->texinfo->vecs[0][3] - surf->texturemins[0];
		i = f;

		// reduce calculations
		t = dist*dist;
		for (s = 0;s < smax;s++, i -= 16)
			sdtable[s] = i*i + t;

		f = DotProduct (impact, surf->texinfo->vecs[1]) + surf->texinfo->vecs[1][3] - surf->texturemins[1];
		i = f;

		maxdist = (int) (cl_dlights[lnum].radius*cl_dlights[lnum].radius); // for comparisons to minimum acceptable light
		// clamp radius to avoid exceeding 8192 entry division table
		if (maxdist > 1048576)
			maxdist = 1048576;
		maxdist3 = maxdist - (int) (dist*dist);
		// convert to 8.8 blocklights format
//		if (!cl_dlights[lnum].dark)
//		{
			f = cl_dlights[lnum].color[0] * maxdist;red = f;
			f = cl_dlights[lnum].color[1] * maxdist;green = f;
			f = cl_dlights[lnum].color[2] * maxdist;blue = f;
		/*
		}
		else // negate for darklight
		{
			f = cl_dlights[lnum].color[0] * -maxdist;red = f;
			f = cl_dlights[lnum].color[1] * -maxdist;green = f;
			f = cl_dlights[lnum].color[2] * -maxdist;blue = f;
		}
		*/
		bl = blocklights;
		for (t = 0;t < tmax;t++,i -= 16)
		{
			td = i*i;
			if (td < maxdist3) // make sure some part of it is visible on this line
			{
				maxdist2 = maxdist - td;
				for (s = 0;s < smax;s++)
				{
					if (sdtable[s] < maxdist2)
					{
						j = dlightdivtable[(sdtable[s]+td) >> 7];
						k = (red   * j) >> 7;bl[0] += k;
						k = (green * j) >> 7;bl[1] += k;
						k = (blue  * j) >> 7;bl[2] += k;
					}
					bl += 3;
				}
			}
			else
				bl+=smax*3; // skip line
		}
	}
}

/*
	R_BuildLightMap

	Combine and scale multiple lightmaps
	After talking it over with LordHavoc, I've decided to switch to using
	 GL_RGB for colored lights and averaging them out for plain white
	 lighting if needed.  Much cleaner that way.  --KB
*/
void
R_BuildLightMap (msurface_t *surf, byte *dest, int stride)
{
	int			smax, tmax;
	int			t;
	int			i, j, size;
	byte		*lightmap;
	unsigned	scale;
	int			maps;
	float		t2;
	unsigned	*bl;

	surf->cached_dlight = (surf->dlightframe == r_framecount);

	smax = (surf->extents[0]>>4)+1;
	tmax = (surf->extents[1]>>4)+1;
	size = smax*tmax;
	lightmap = surf->samples;

	// set to full bright if no light data
	if (/*r_fullbright->value ||*/ !cl.worldmodel->lightdata)
	{
		bl = blocklights;
		for (i=0 ; i<size ; i++)
		{
			*bl++ = 255*256;
			*bl++ = 255*256;
			*bl++ = 255*256;
		}
		goto store;
	}

	// clear to no light
	bl = blocklights;
	for (i=0 ; i<size ; i++)
	{
		*bl++ = 0;
		*bl++ = 0;
		*bl++ = 0;
	}
	bl = blocklights;

	// add all the lightmaps
	if (lightmap)
		for (maps = 0;
			maps < MAXLIGHTMAPS && surf->styles[maps] != 255;
			maps++)
		{
			scale = d_lightstylevalue[surf->styles[maps]];
			surf->cached_light[maps] = scale;	// 8.8 fraction
			bl = blocklights;
			for (i=0 ; i<size ; i++)
			{
				*bl++ += *lightmap++ * scale;
				*bl++ += *lightmap++ * scale;
				*bl++ += *lightmap++ * scale;
			}
		}

	// add all the dynamic lights
	if (surf->dlightframe == r_framecount)
		R_AddDynamicLights (surf);

store:
	// bound and shift
	if (gl_colorlights->value)
	{
		stride -= smax * 3;
		bl = blocklights;
		if (lighthalf)
		{
			for (i = 0; i < tmax; i++, dest += stride)
				for (j=0 ; j<smax ; j++)
				{
					t = (int) *bl++ >> 8;
					*dest++ = bound(0, t, 255);
					t = (int) *bl++ >> 8;
					*dest++ = bound(0, t, 255);
					t = (int) *bl++ >> 8;
					*dest++ = bound(0, t, 255);
				}
		}
		else
		{
			for (i = 0; i < tmax; i++, dest += stride)
				for (j=0 ; j<smax ; j++)
				{
					t = (int) *bl++ >> 7;
					*dest++ = bound(0, t, 255);
					t = (int) *bl++ >> 7;
					*dest++ = bound(0, t, 255);
					t = (int) *bl++ >> 7;
					*dest++ = bound(0, t, 255);
				}
		}
	}
	else
	{
		stride -= smax;
		bl = blocklights;
		if (lighthalf)
		{
			for (i = 0; i < tmax; i++, dest += stride)
				for (j=0 ; j<smax ; j++)
				{
					t = (int) *bl++ >> 8;
					t2 = bound(0, t, 255);
					t = (int) *bl++ >> 8;
					t2 += bound(0, t, 255);
					t = (int) *bl++ >> 8;
					t2 += bound(0, t, 255);
					t2 *= (1.0/3.0);
					*dest++ = t2;
				}
		}
		else
		{
			for (i = 0; i < tmax; i++, dest += stride)
				for (j=0 ; j<smax ; j++)
				{
					t = (int) *bl++ >> 7;
					t2 = bound(0, t, 255);
					t = (int) *bl++ >> 7;
					t2 += bound(0, t, 255);
					t = (int) *bl++ >> 7;
					t2 += bound(0, t, 255);
					t2 *= (1.0/3.0);
					*dest++ = t2;
				}
		}
	}
}

/*
===============
R_TextureAnimation

Returns the proper texture for a given time and base texture
===============
*/
texture_t *R_TextureAnimation (texture_t *base)
{
	int		relative;
	int		count;

	if (currententity->frame)
	{
		if (base->alternate_anims)
			base = base->alternate_anims;
	}
	
	if (!base->anim_total)
		return base;

	relative = (int)(cl.time*10) % base->anim_total;

	count = 0;	
	while (base->anim_min > relative || base->anim_max <= relative)
	{
		base = base->anim_next;
		if (!base)
			Sys_Error ("R_TextureAnimation: broken cycle");
		if (++count > 100)
			Sys_Error ("R_TextureAnimation: infinite cycle");
	}

	return base;
}


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

	BRUSH MODELS

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


extern	int		solidskytexture;
extern	int		alphaskytexture;
extern	float	speedscale;		// for top sky and bottom sky

lpMTexFUNC qglMTexCoord2f = NULL;
lpSelTexFUNC qglSelectTexture = NULL;

void GL_UploadLightmap(int i, int x, int y, int w, int h)
{
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, y, BLOCK_WIDTH, h, gl_lightmap_format, GL_UNSIGNED_BYTE, lightmaps[i] + (y * BLOCK_WIDTH) * lightmap_bytes);
}

/*
================
R_DrawSequentialPoly

Systems that have fast state and texture changes can
just do everything as it passes with no need to sort
================
*/
void R_DrawMultitexturePoly (msurface_t *s)
{
	int			maps;
	float		*v;
	int			i;

	c_brush_polys++;

	i = s->lightmaptexturenum;

	glColor3f(1,1,1);
	// Binds world to texture env 0
	qglSelectTexture (gl_mtex_enum+0);
	glBindTexture (GL_TEXTURE_2D, R_TextureAnimation (s->texinfo->texture)->gl_texturenum);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
	glEnable(GL_TEXTURE_2D);
	// Binds lightmap to texenv 1
	qglSelectTexture (gl_mtex_enum+1);
	glBindTexture (GL_TEXTURE_2D, lightmap_textures + i);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	glEnable(GL_TEXTURE_2D);

	// check for lightmap modification
	if (r_dynamic->value)
	{
		for (maps = 0;maps < MAXLIGHTMAPS && s->styles[maps] != 255;maps++)
			if (d_lightstylevalue[s->styles[maps]] != s->cached_light[maps])
				goto dynamic;

		if (s->dlightframe == r_framecount	// dynamic this frame
			|| s->cached_dlight)			// dynamic previously
		{
dynamic:
			R_BuildLightMap (s, lightmaps[s->lightmaptexturenum] + (s->light_t * BLOCK_WIDTH + s->light_s) * lightmap_bytes, BLOCK_WIDTH*lightmap_bytes);
			GL_UploadLightmap(i, s->light_s, s->light_t, (s->extents[0]>>4)+1, (s->extents[1]>>4)+1);
		}
	}

	glBegin(GL_POLYGON);
	v = s->polys->verts[0];
	for (i=0 ; i<s->polys->numverts ; i++, v+= VERTEXSIZE)
	{
		qglMTexCoord2f (gl_mtex_enum + 0, v[3], v[4]);
		qglMTexCoord2f (gl_mtex_enum + 1, v[5], v[6]);
		glVertex3fv (v);
	}
	glEnd ();
	glDisable(GL_TEXTURE_2D);
	qglSelectTexture (gl_mtex_enum+0);
	glEnable(GL_TEXTURE_2D);
}

/*
================
R_BlendLightmaps
================
*/
void R_BlendLightmaps (void)
{
	int			i, j;
	glpoly_t	*p;
	float		*v;

	glDepthMask (0);		// don't bother writing Z

	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	glBlendFunc (GL_ZERO, GL_SRC_COLOR);
	glEnable(GL_BLEND);

	for (i=0 ; i<MAX_LIGHTMAPS ; i++)
	{
		p = lightmap_polys[i];
		if (!p)
			continue;
		glBindTexture (GL_TEXTURE_2D, lightmap_textures+i);
		if (lightmap_modified[i])
		{
			GL_UploadLightmap(i, lightmap_rectchange[i].l, lightmap_rectchange[i].t, lightmap_rectchange[i].w, lightmap_rectchange[i].h);
			lightmap_modified[i] = false;
		}
		for (;p;p = p->chain)
		{
			glBegin (GL_POLYGON);
			v = p->verts[0];
			for (j=0 ; j<p->numverts ; j++, v+= VERTEXSIZE)
			{
				glTexCoord2fv (&v[5]);
				glVertex3fv (v);
			}
			glEnd ();
		}
	}

	// Return to normal blending  --KB
	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

	glDepthMask (1);		// back to normal Z buffering
}

/*
================
R_RenderBrushPoly
================
*/
void R_RenderBrushPoly (msurface_t *fa)
{
	byte		*base;
	int			maps;
	glRect_t	*theRect;
	int			i;
	float		*v;
	int			smax, tmax;

	c_brush_polys++;

	glBindTexture (GL_TEXTURE_2D, R_TextureAnimation (fa->texinfo->texture)->gl_texturenum);

	glBegin (GL_POLYGON);
	v = fa->polys->verts[0];
	for (i = 0;i < fa->polys->numverts;i++, v += VERTEXSIZE)
	{
		glTexCoord2fv (&v[3]);
		glVertex3fv (v);
	}
	glEnd ();

	// add the poly to the proper lightmap chain

	fa->polys->chain = lightmap_polys[fa->lightmaptexturenum];
	lightmap_polys[fa->lightmaptexturenum] = fa->polys;

	// check for lightmap modification
	for (maps = 0 ; maps < MAXLIGHTMAPS && fa->styles[maps] != 255 ;
		 maps++)
		if (d_lightstylevalue[fa->styles[maps]] != fa->cached_light[maps])
			goto dynamic;

	if (fa->dlightframe == r_framecount	// dynamic this frame
		|| fa->cached_dlight)			// dynamic previously
	{
dynamic:
		if (r_dynamic->value)
		{
			lightmap_modified[fa->lightmaptexturenum] = true;
			theRect = &lightmap_rectchange[fa->lightmaptexturenum];
			if (fa->light_t < theRect->t) {
				if (theRect->h)
					theRect->h += theRect->t - fa->light_t;
				theRect->t = fa->light_t;
			}
			if (fa->light_s < theRect->l) {
				if (theRect->w)
					theRect->w += theRect->l - fa->light_s;
				theRect->l = fa->light_s;
			}
			smax = (fa->extents[0]>>4)+1;
			tmax = (fa->extents[1]>>4)+1;
			if ((theRect->w + theRect->l) < (fa->light_s + smax))
				theRect->w = (fa->light_s-theRect->l)+smax;
			if ((theRect->h + theRect->t) < (fa->light_t + tmax))
				theRect->h = (fa->light_t-theRect->t)+tmax;
			base = lightmaps[fa->lightmaptexturenum] + (fa->light_t * BLOCK_WIDTH + fa->light_s) * lightmap_bytes;
			R_BuildLightMap (fa, base, BLOCK_WIDTH*lightmap_bytes);
		}
	}
}

void GL_WaterSurface(msurface_t *s)
{
	int i;
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	if (lighthalf)
		glColor4f(0.5,0.5,0.5, r_wateralpha->value);
	else
		glColor4f(1,1,1, r_wateralpha->value);
	i = s->texinfo->texture->gl_texturenum;
	glBindTexture (GL_TEXTURE_2D, i);
	if (r_wateralpha->value < 1.0)
	{
		glDepthMask(0);
		EmitWaterPolys (s);
		glDepthMask(1);
	}
	else
		EmitWaterPolys (s);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
}

/*
================
R_DrawWaterSurfaces
================
*/
void R_DrawWaterSurfaces (void)
{
	int			i;
	msurface_t	*s;

	if (!waterchain)
		return;

	// go back to the world matrix

	glLoadMatrixf (r_world_matrix);

	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	if (lighthalf)
		glColor4f(0.5,0.5,0.5, r_wateralpha->value);
	else
		glColor4f(1,1,1, r_wateralpha->value);
	if (r_wateralpha->value < 1.0)
		glDepthMask(0);

	i = -1;
	for (s = waterchain;s;s = s->texturechain)
	{
		if (i != s->texinfo->texture->gl_texturenum)
		{
			i = s->texinfo->texture->gl_texturenum;
			glBindTexture (GL_TEXTURE_2D, i);
		}
		EmitWaterPolys (s);
	}
	
	waterchain = NULL;

	glColor3f(1,1,1);
	if (r_wateralpha->value < 1.0)
		glDepthMask(1);
}


/*
================
DrawTextureChains
================
*/
void DrawTextureChains (void)
{
	int		i;
	msurface_t	*s;

	for (i=0 ; i<cl.worldmodel->numtextures ; i++)
	{
		if (!cl.worldmodel->textures[i])
			continue;
		for (s = cl.worldmodel->textures[i]->texturechain;s;s = s->texturechain)
			R_RenderBrushPoly (s);

		cl.worldmodel->textures[i]->texturechain = NULL;
	}
}

/*
=================
R_DrawBrushModel
=================
*/
void R_DrawBrushModel (entity_t *e)
{
	int			i;
	int			k;
	vec3_t		mins, maxs;
	msurface_t	*psurf;
	float		dot;
	mplane_t	*pplane;
	model_t		*clmodel;
	qboolean	rotated;

	currententity = e;

	clmodel = e->model;

	if (e->angles[0] || e->angles[1] || e->angles[2])
	{
		rotated = true;
		for (i=0 ; i<3 ; i++)
		{
			mins[i] = e->origin[i] - clmodel->radius;
			maxs[i] = e->origin[i] + clmodel->radius;
		}
	}
	else
	{
		rotated = false;
		VectorAdd (e->origin, clmodel->mins, mins);
		VectorAdd (e->origin, clmodel->maxs, maxs);
	}

	if (R_CullBox (mins, maxs))
		return;

	glColor3f (1, 1, 1);

	memset (lightmap_polys, 0, sizeof(lightmap_polys));

	VectorSubtract (r_refdef.vieworg, e->origin, modelorg);
	if (rotated)
	{
		vec3_t	temp;
		vec3_t	forward, right, up;

		VectorCopy (modelorg, temp);
		AngleVectors (e->angles, forward, right, up);
		modelorg[0] = DotProduct (temp, forward);
		modelorg[1] = -DotProduct (temp, right);
		modelorg[2] = DotProduct (temp, up);
	}

	psurf = &clmodel->surfaces[clmodel->firstmodelsurface];

	// calculate dynamic lighting for bmodel if it's not an
	// instanced model
	if (clmodel->firstmodelsurface != 0 && !gl_flashblend->value)
	{
		vec3_t lightorigin;
		for (k=0 ; k<MAX_DLIGHTS ; k++)
		{
			if ((cl_dlights[k].die < cl.time) ||
				(!cl_dlights[k].radius))
				continue;

			VectorSubtract(cl_dlights[k].origin, e->origin, lightorigin);
			R_MarkLights (lightorigin, &cl_dlights[k], 1<<k,
				clmodel->nodes + clmodel->hulls[0].firstclipnode);
		}
	}

	glPushMatrix ();
	e->angles[0] = -e->angles[0];	// stupid quake bug
	R_RotateForEntity (e);
	e->angles[0] = -e->angles[0];	// stupid quake bug

	// LordHavoc: anyone without multitexture won't want texsort 0 anyway...
	if (!gl_mtexable)
		gl_texsort->value = 1;

	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

	//
	// draw texture
	//
	for (i=0 ; i<clmodel->nummodelsurfaces ; i++, psurf++)
	{
		if (psurf->flags & SURF_DRAWSKY)
			return;

		// 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)))
		{
			if (psurf->flags & SURF_DRAWTURB)
				GL_WaterSurface(psurf);
			else if (gl_texsort->value)
				R_RenderBrushPoly (psurf);
			else
				R_DrawMultitexturePoly (psurf);
		}
	}

	if (gl_texsort->value)
		R_BlendLightmaps ();

	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glEnable(GL_BLEND);

	glPopMatrix ();
}

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

	WORLD MODEL

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

/*
================
R_RecursiveWorldNode
================
*/
void R_RecursiveWorldNode (mnode_t *node)
{
	int			c, side;
	mplane_t	*plane;
	msurface_t	*surf, **mark;
	mleaf_t		*pleaf;
	double		dot;

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

	if (node->visframe != r_visframecount)
		return;
	if (R_CullBox (node->minmaxs, node->minmaxs+3))
		return;

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

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

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

		return;
	}

// 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;
	}

	side = dot < 0;

// recurse down the children, front side first
	// LordHavoc: save a stack frame by avoiding a call
	if (node->children[side]->contents != CONTENTS_SOLID && node->children[side]->visframe == r_visframecount && !R_CullBox (node->children[side]->minmaxs, node->children[side]->minmaxs+3))
		R_RecursiveWorldNode (node->children[side]);

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

		if (dot < -BACKFACE_EPSILON)
			side = SURF_PLANEBACK;
		else if (dot > BACKFACE_EPSILON)
			side = 0;

		for ( ; c ; c--, surf++)
		{
			if (surf->visframe != r_framecount)
				continue;

			if ((dot < 0) ^ !!(surf->flags & SURF_PLANEBACK))
				continue;		// wrong side

			if (surf->flags & SURF_DRAWSKY)
				continue;

			if (surf->flags & SURF_DRAWTURB)
			{
				surf->texturechain = waterchain;
				waterchain = surf;
			}
			else if (gl_texsort->value)
			{
				surf->texturechain = surf->texinfo->texture->texturechain;
				surf->texinfo->texture->texturechain = surf;
			}
			else
				R_DrawMultitexturePoly (surf);
		}
	}

// recurse down the back side
	// LordHavoc: save a stack frame by avoiding a call
	side = !side;
	if (node->children[side]->contents != CONTENTS_SOLID && node->children[side]->visframe == r_visframecount && !R_CullBox (node->children[side]->minmaxs, node->children[side]->minmaxs+3))
		R_RecursiveWorldNode (node->children[side]);
}



/*
=============
R_DrawWorld
=============
*/
void R_DrawWorld (void)
{
	entity_t	ent;

	memset (&ent, 0, sizeof(ent));
	ent.model = cl.worldmodel;

	VectorCopy (r_refdef.vieworg, modelorg);

	currententity = &ent;

	// LordHavoc: anyone without multitexture won't want texsort 0 anyway...
	if (!gl_mtexable)
		gl_texsort->value = 1;

	glColor3f (1.0, 1.0, 1.0);
	memset (lightmap_polys, 0, sizeof(lightmap_polys));
	// Be sure to clear the skybox --KB
	R_DrawSky ();

	glDisable(GL_BLEND);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

	R_RecursiveWorldNode (cl.worldmodel->nodes);

	DrawTextureChains ();

	if (gl_texsort->value)
		R_BlendLightmaps ();

	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glEnable(GL_BLEND);
}


/*
===============
R_MarkLeaves
===============
*/
void R_MarkLeaves (void)
{
	byte	*vis;
	mnode_t	*node;
	int		i;
	byte	solid[4096];

	if (r_oldviewleaf == r_viewleaf && !r_novis->value)
		return;
	
	if (mirror)
		return;

	r_visframecount++;
	r_oldviewleaf = r_viewleaf;

	if (r_novis->value)
	{
		vis = solid;
		memset (solid, 0xff, (cl.worldmodel->numleafs+7)>>3);
	}
	else
		vis = Mod_LeafPVS (r_viewleaf, cl.worldmodel);
		
	for (i=0 ; i<cl.worldmodel->numleafs ; i++)
	{
		if (vis[i>>3] & (1<<(i&7)))
		{
			node = (mnode_t *)&cl.worldmodel->leafs[i+1];
			do
			{
				if (node->visframe == r_visframecount)
					break;
				node->visframe = r_visframecount;
				node = node->parent;
			} while (node);
		}
	}
}



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

  LIGHTMAP ALLOCATION

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

// returns a texture number and the position inside it
int AllocBlock (int w, int h, int *x, int *y)
{
	int		i, j;
	int		best, best2;
	int		texnum;

	for (texnum=0 ; texnum<MAX_LIGHTMAPS ; texnum++)
	{
		best = BLOCK_HEIGHT;

		for (i=0 ; i<BLOCK_WIDTH-w ; i++)
		{
			best2 = 0;

			for (j=0 ; j<w ; j++)
			{
				if (allocated[texnum][i+j] >= best)
					break;
				if (allocated[texnum][i+j] > best2)
					best2 = allocated[texnum][i+j];
			}
			if (j == w)
			{
				// this is a valid spot
				*x = i;
				*y = best = best2;
			}
		}

		if (best + h > BLOCK_HEIGHT)
			continue;

		// LordHavoc: allocate lightmaps only as needed
		if (!lightmaps[texnum])
			lightmaps[texnum] = calloc(BLOCK_WIDTH * BLOCK_HEIGHT, 3);

		for (i=0 ; i<w ; i++)
			allocated[texnum][*x + i] = best + h;

		return texnum;
	}

	Sys_Error ("AllocBlock: full");
	return 0;
}


mvertex_t	*r_pcurrentvertbase;
model_t		*currentmodel;

int	nColinElim;

/*
================
BuildSurfaceDisplayList
================
*/
void BuildSurfaceDisplayList (msurface_t *fa)
{
	int			i, lindex, lnumverts;
	medge_t		*pedges, *r_pedge;
	int			vertpage;
	float		*vec;
	float		s, t;
	glpoly_t	*poly;

// reconstruct the polygon
	pedges = currentmodel->edges;
	lnumverts = fa->numedges;
	vertpage = 0;

	//
	// draw texture
	//
	poly = Hunk_Alloc (sizeof(glpoly_t) + (lnumverts-4) * VERTEXSIZE*sizeof(float));
	poly->next = fa->polys;
	poly->flags = fa->flags;
	fa->polys = poly;
	poly->numverts = lnumverts;

	for (i=0 ; i<lnumverts ; i++)
	{
		lindex = currentmodel->surfedges[fa->firstedge + i];

		if (lindex > 0)
		{
			r_pedge = &pedges[lindex];
			vec = r_pcurrentvertbase[r_pedge->v[0]].position;
		}
		else
		{
			r_pedge = &pedges[-lindex];
			vec = r_pcurrentvertbase[r_pedge->v[1]].position;
		}
		s = DotProduct (vec, fa->texinfo->vecs[0]) + fa->texinfo->vecs[0][3];
		s /= fa->texinfo->texture->width;

		t = DotProduct (vec, fa->texinfo->vecs[1]) + fa->texinfo->vecs[1][3];
		t /= fa->texinfo->texture->height;

		VectorCopy (vec, poly->verts[i]);
		poly->verts[i][3] = s;
		poly->verts[i][4] = t;

		//
		// lightmap texture coordinates
		//
		s = DotProduct (vec, fa->texinfo->vecs[0]) + fa->texinfo->vecs[0][3];
		s -= fa->texturemins[0];
		s += fa->light_s*16;
		s += 8;
		s /= BLOCK_WIDTH*16; //fa->texinfo->texture->width;

		t = DotProduct (vec, fa->texinfo->vecs[1]) + fa->texinfo->vecs[1][3];
		t -= fa->texturemins[1];
		t += fa->light_t*16;
		t += 8;
		t /= BLOCK_HEIGHT*16; //fa->texinfo->texture->height;

		poly->verts[i][5] = s;
		poly->verts[i][6] = t;
	}

	//
	// remove co-linear points - Ed
	//
	if (!gl_keeptjunctions->value && !(fa->flags & SURF_UNDERWATER) )
	{
		for (i = 0 ; i < lnumverts ; ++i)
		{
			vec3_t v1, v2;
			float *prev, *this, *next;

			prev = poly->verts[(i + lnumverts - 1) % lnumverts];
			this = poly->verts[i];
			next = poly->verts[(i + 1) % lnumverts];

			VectorSubtract( this, prev, v1 );
			VectorNormalize( v1 );
			VectorSubtract( next, prev, v2 );
			VectorNormalize( v2 );

			// skip co-linear points
#			define COLINEAR_EPSILON 0.001
			if ((fabs( v1[0] - v2[0] ) <= COLINEAR_EPSILON) &&
				(fabs( v1[1] - v2[1] ) <= COLINEAR_EPSILON) && 
				(fabs( v1[2] - v2[2] ) <= COLINEAR_EPSILON))
			{
				int j;
				for (j = i + 1; j < lnumverts; ++j)
				{
					int k;
					for (k = 0; k < VERTEXSIZE; ++k)
						poly->verts[j - 1][k] = poly->verts[j][k];
				}
				--lnumverts;
				++nColinElim;
				// retry next vertex next time, which is now current vertex
				--i;
			}
		}
	}
	poly->numverts = lnumverts;

}

/*
========================
GL_CreateSurfaceLightmap
========================
*/
void GL_CreateSurfaceLightmap (msurface_t *surf)
{
	int		smax, tmax;
	byte	*base;

	if (surf->flags & (SURF_DRAWSKY|SURF_DRAWTURB))
		return;

	smax = (surf->extents[0]>>4)+1;
	tmax = (surf->extents[1]>>4)+1;

	surf->lightmaptexturenum = AllocBlock (smax, tmax, &surf->light_s, &surf->light_t);
	base = lightmaps[surf->lightmaptexturenum] + (surf->light_t * BLOCK_WIDTH + surf->light_s) * lightmap_bytes;
	R_BuildLightMap (surf, base, BLOCK_WIDTH*lightmap_bytes);
}


/*
==================
GL_BuildLightmaps

Builds the lightmap texture
with all the surfaces from all brush models
==================
*/
void GL_BuildLightmaps (void)
{
	int		i, j;
	model_t	*m;

	memset (allocated, 0, sizeof(allocated));

	r_framecount = 1;		// no dlightcache

	if (!lightmap_textures)
	{
		lightmap_textures = texture_extension_number;
		texture_extension_number += MAX_LIGHTMAPS;
	}

	gl_colorlights = Cvar_Get ("gl_colorlights", "1", CVAR_ROM,
			"Whether to use RGB lightmaps or not");

	if (gl_colorlights->value)
	{
		gl_lightmap_format = GL_RGB;
		lightmap_bytes = 3;
	}
	else
	{
		gl_lightmap_format = GL_LUMINANCE;
		lightmap_bytes = 1;
	}

	for (j=1 ; j<MAX_MODELS ; j++)
	{
		m = cl.model_precache[j];
		if (!m)
			break;
		if (m->name[0] == '*')
			continue;
		r_pcurrentvertbase = m->vertexes;
		currentmodel = m;
		for (i=0 ; i<m->numsurfaces ; i++)
		{
			if ( m->surfaces[i].flags & SURF_DRAWTURB )
				continue;
			if ( m->surfaces[i].flags & SURF_DRAWSKY )
				continue;
			GL_CreateSurfaceLightmap (m->surfaces + i);
			BuildSurfaceDisplayList (m->surfaces + i);
		}
	}

 	if (gl_mtexable && !gl_texsort->value)
		qglSelectTexture (gl_mtex_enum+1);

	//
	// upload all lightmaps that were filled
	//
	for (i=0 ; i<MAX_LIGHTMAPS ; i++)
	{
		if (!allocated[i][0])
			break;		// no more used
		lightmap_modified[i] = false;
		lightmap_rectchange[i].l = BLOCK_WIDTH;
		lightmap_rectchange[i].t = BLOCK_HEIGHT;
		lightmap_rectchange[i].w = 0;
		lightmap_rectchange[i].h = 0;
		glBindTexture (GL_TEXTURE_2D, lightmap_textures + i);
		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexImage2D (GL_TEXTURE_2D, 0, lightmap_bytes, BLOCK_WIDTH,
				BLOCK_HEIGHT, 0, gl_lightmap_format,
				GL_UNSIGNED_BYTE, lightmaps[i]);
	}

 	if (gl_mtexable && !gl_texsort->value)
		qglSelectTexture (gl_mtex_enum+0);
}