#include "quakedef.h"

static int max_meshs;
static int max_batch;
static int max_verts; // always max_meshs * 3
#define TRANSDEPTHRES 4096

static cvar_t gl_mesh_maxtriangles = {0, "gl_mesh_maxtriangles", "21760"};
static cvar_t gl_mesh_batchtriangles = {0, "gl_mesh_batchtriangles", "1024"};
static cvar_t gl_mesh_merge = {0, "gl_mesh_merge", "1"};
static cvar_t gl_mesh_floatcolors = {0, "gl_mesh_floatcolors", "1"};

typedef struct buf_mesh_s
{
	struct buf_mesh_s *next;
	int depthmask;
	int blendfunc1, blendfunc2;
	int textures[MAX_TEXTUREUNITS];
	float texturergbscale[MAX_TEXTUREUNITS];
	int firsttriangle;
	int triangles;
}
buf_mesh_t;

typedef struct buf_transtri_s
{
	struct buf_transtri_s *next;
	buf_mesh_t *mesh;
	int index[3];
}
buf_transtri_t;

typedef struct buf_tri_s
{
	int index[3];
}
buf_tri_t;

typedef struct
{
	float v[4];
}
buf_vertex_t;

typedef struct
{
	float c[4];
}
buf_fcolor_t;

typedef struct
{
	byte c[4];
}
buf_bcolor_t;

typedef struct
{
	float t[2];
}
buf_texcoord_t;

static float meshfarclip;
static int currentmesh, currenttriangle, currentvertex, backendunits, backendactive, meshmerge, floatcolors, transranout;
static buf_mesh_t *buf_mesh;
static buf_tri_t *buf_tri;
static buf_vertex_t *buf_vertex;
static buf_fcolor_t *buf_fcolor;
static buf_bcolor_t *buf_bcolor;
static buf_texcoord_t *buf_texcoord[MAX_TEXTUREUNITS];

static int currenttransmesh, currenttransvertex, currenttranstriangle;
static buf_mesh_t *buf_transmesh;
static buf_transtri_t *buf_transtri;
static buf_transtri_t **buf_transtri_list;
static buf_vertex_t *buf_transvertex;
static buf_fcolor_t *buf_transfcolor;
static buf_bcolor_t *buf_transbcolor;
static buf_texcoord_t *buf_transtexcoord[MAX_TEXTUREUNITS];

static mempool_t *gl_backend_mempool;

static void gl_backend_start(void)
{
	int i;

	max_verts = max_meshs * 3;

	gl_backend_mempool = Mem_AllocPool("GL_Backend");

#define BACKENDALLOC(var, count, sizeofstruct)\
	{\
		var = Mem_Alloc(gl_backend_mempool, count * sizeof(sizeofstruct));\
		if (var == NULL)\
			Sys_Error("gl_backend_start: unable to allocate memory\n");\
		memset(var, 0, count * sizeof(sizeofstruct));\
	}

	BACKENDALLOC(buf_mesh, max_meshs, buf_mesh_t)
	BACKENDALLOC(buf_tri, max_meshs, buf_tri_t)
	BACKENDALLOC(buf_vertex, max_verts, buf_vertex_t)
	BACKENDALLOC(buf_fcolor, max_verts, buf_fcolor_t)
	BACKENDALLOC(buf_bcolor, max_verts, buf_bcolor_t)

	BACKENDALLOC(buf_transmesh, max_meshs, buf_mesh_t)
	BACKENDALLOC(buf_transtri, max_meshs, buf_transtri_t)
	BACKENDALLOC(buf_transtri_list, TRANSDEPTHRES, buf_transtri_t *)
	BACKENDALLOC(buf_transvertex, max_verts, buf_vertex_t)
	BACKENDALLOC(buf_transfcolor, max_verts, buf_fcolor_t)
	BACKENDALLOC(buf_transbcolor, max_verts, buf_bcolor_t)

	for (i = 0;i < MAX_TEXTUREUNITS;i++)
	{
		// only allocate as many texcoord arrays as we need
		if (i < gl_textureunits)
		{
			BACKENDALLOC(buf_texcoord[i], max_verts, buf_texcoord_t)
			BACKENDALLOC(buf_transtexcoord[i], max_verts, buf_texcoord_t)
		}
		else
		{
			buf_texcoord[i] = NULL;
			buf_transtexcoord[i] = NULL;
		}
	}
	backendunits = min(MAX_TEXTUREUNITS, gl_textureunits);
	backendactive = true;
}

static void gl_backend_shutdown(void)
{
	int i;
	/*
#define BACKENDFREE(var)\
	if (var)\
	{\
		Mem_Free(var);\
		var = NULL;\
	}
	*/
#define BACKENDFREE(var) var = NULL;

	BACKENDFREE(buf_mesh)
	BACKENDFREE(buf_tri)
	BACKENDFREE(buf_vertex)
	BACKENDFREE(buf_fcolor)
	BACKENDFREE(buf_bcolor)

	BACKENDFREE(buf_transmesh)
	BACKENDFREE(buf_transtri)
	BACKENDFREE(buf_transtri_list)
	BACKENDFREE(buf_transvertex)
	BACKENDFREE(buf_transfcolor)
	BACKENDFREE(buf_transbcolor)

	for (i = 0;i < MAX_TEXTUREUNITS;i++)
	{
		BACKENDFREE(buf_texcoord[i])
		BACKENDFREE(buf_transtexcoord[i])
	}

	Mem_FreePool(&gl_backend_mempool);

	backendunits = 0;
	backendactive = false;
}

static void gl_backend_bufferchanges(int init)
{
	// 21760 is (65536 / 3) rounded off to a multiple of 128
	if (gl_mesh_maxtriangles.integer < 256)
		Cvar_SetValue("gl_mesh_maxtriangles", 256);
	if (gl_mesh_maxtriangles.integer > 21760)
		Cvar_SetValue("gl_mesh_maxtriangles", 21760);

	if (gl_mesh_batchtriangles.integer < 0)
		Cvar_SetValue("gl_mesh_batchtriangles", 0);
	if (gl_mesh_batchtriangles.integer > gl_mesh_maxtriangles.integer)
		Cvar_SetValue("gl_mesh_batchtriangles", gl_mesh_maxtriangles.integer);

	max_batch = gl_mesh_batchtriangles.integer;

	if (max_meshs != gl_mesh_maxtriangles.integer)
	{
		max_meshs = gl_mesh_maxtriangles.integer;

		if (!init)
		{
			gl_backend_shutdown();
			gl_backend_start();
		}
	}
}

float r_farclip, r_newfarclip;

static void gl_backend_newmap(void)
{
	r_farclip = r_newfarclip = 2048.0f;
}

int polyindexarray[768];

void gl_backend_init(void)
{
	int i;
	Cvar_RegisterVariable(&gl_mesh_maxtriangles);
	Cvar_RegisterVariable(&gl_mesh_batchtriangles);
	Cvar_RegisterVariable(&gl_mesh_merge);
	Cvar_RegisterVariable(&gl_mesh_floatcolors);
	R_RegisterModule("GL_Backend", gl_backend_start, gl_backend_shutdown, gl_backend_newmap);
	gl_backend_bufferchanges(true);
	for (i = 0;i < 256;i++)
	{
		polyindexarray[i*3+0] = 0;
		polyindexarray[i*3+1] = i + 1;
		polyindexarray[i*3+2] = i + 2;
	}
}

static float viewdist;

int c_meshtris;

// called at beginning of frame
void R_Mesh_Clear(void)
{
	if (!backendactive)
		Sys_Error("R_Mesh_Clear: called when backend is not active\n");

	gl_backend_bufferchanges(false);

	currentmesh = 0;
	currenttriangle = 0;
	currentvertex = 0;
	currenttransmesh = 0;
	currenttranstriangle = 0;
	currenttransvertex = 0;
	meshfarclip = 0;
	meshmerge = gl_mesh_merge.integer;
	floatcolors = gl_mesh_floatcolors.integer;
	transranout = false;
	viewdist = DotProduct(r_origin, vpn);

	c_meshtris = 0;
}

#ifdef DEBUGGL
void GL_PrintError(int errornumber, char *filename, int linenumber)
{
	switch(errornumber)
	{
	case GL_INVALID_ENUM:
		Con_Printf("GL_INVALID_ENUM at %s:%i\n", filename, linenumber);
		break;
	case GL_INVALID_VALUE:
		Con_Printf("GL_INVALID_VALUE at %s:%i\n", filename, linenumber);
		break;
	case GL_INVALID_OPERATION:
		Con_Printf("GL_INVALID_OPERATION at %s:%i\n", filename, linenumber);
		break;
	case GL_STACK_OVERFLOW:
		Con_Printf("GL_STACK_OVERFLOW at %s:%i\n", filename, linenumber);
		break;
	case GL_STACK_UNDERFLOW:
		Con_Printf("GL_STACK_UNDERFLOW at %s:%i\n", filename, linenumber);
		break;
	case GL_OUT_OF_MEMORY:
		Con_Printf("GL_OUT_OF_MEMORY at %s:%i\n", filename, linenumber);
		break;
	case GL_TABLE_TOO_LARGE:
		Con_Printf("GL_TABLE_TOO_LARGE at %s:%i\n", filename, linenumber);
		break;
	default:
		Con_Printf("GL UNKNOWN (%i) at %s:%i\n", errornumber, filename, linenumber);
		break;
	}
}

int errornumber = 0;
#endif

// renders mesh buffers, called to flush buffers when full
void R_Mesh_Render(void)
{
	int i, k, blendfunc1, blendfunc2, blend, depthmask, unit = 0, clientunit = 0, firsttriangle, triangles, texture[MAX_TEXTUREUNITS];
	float farclip, texturergbscale[MAX_TEXTUREUNITS];
	buf_mesh_t *mesh;
	if (!backendactive)
		Sys_Error("R_Mesh_Render: called when backend is not active\n");
	if (!currentmesh)
		return;

CHECKGLERROR

	farclip = meshfarclip + 256.0f - viewdist; // + 256 just to be safe

	// push out farclip for next frame
	if (farclip > r_newfarclip)
		r_newfarclip = ceil((farclip + 255) / 256) * 256 + 256;

	for (i = 0;i < backendunits;i++)
		texturergbscale[i] = 1;

	glEnable(GL_CULL_FACE);
CHECKGLERROR
	glCullFace(GL_FRONT);
CHECKGLERROR
	glEnable(GL_DEPTH_TEST);
CHECKGLERROR
	blendfunc1 = GL_ONE;
	blendfunc2 = GL_ZERO;
	glBlendFunc(blendfunc1, blendfunc2);
CHECKGLERROR
	blend = 0;
	glDisable(GL_BLEND);
CHECKGLERROR
	depthmask = true;
	glDepthMask((GLboolean) depthmask);
CHECKGLERROR

CHECKGLERROR
	glVertexPointer(3, GL_FLOAT, sizeof(buf_vertex_t), buf_vertex);
CHECKGLERROR
	glEnableClientState(GL_VERTEX_ARRAY);
CHECKGLERROR
	if (floatcolors)
	{
		glColorPointer(4, GL_FLOAT, sizeof(buf_fcolor_t), buf_fcolor);
CHECKGLERROR
	}
	else
	{
		glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(buf_bcolor_t), buf_bcolor);
CHECKGLERROR
	}
	glEnableClientState(GL_COLOR_ARRAY);
CHECKGLERROR

	if (backendunits > 1)
	{
		for (i = 0;i < backendunits;i++)
		{
			qglActiveTexture(GL_TEXTURE0_ARB + (unit = i));
CHECKGLERROR
			glBindTexture(GL_TEXTURE_2D, (texture[i] = 0));
CHECKGLERROR
			glDisable(GL_TEXTURE_2D);
CHECKGLERROR
			if (gl_combine.integer)
			{
				glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_MODULATE);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB_ARB, GL_CONSTANT_ARB);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB_ARB, GL_SRC_COLOR);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB_ARB, GL_SRC_COLOR);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB_ARB, GL_SRC_ALPHA);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_MODULATE);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_TEXTURE);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_ALPHA_ARB, GL_PREVIOUS_ARB);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_ALPHA_ARB, GL_CONSTANT_ARB);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA_ARB, GL_SRC_ALPHA);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA_ARB, GL_SRC_ALPHA);
CHECKGLERROR
				glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_ALPHA_ARB, GL_SRC_ALPHA);
CHECKGLERROR
				glTexEnvf(GL_TEXTURE_ENV, GL_RGB_SCALE_ARB, 1.0f);
CHECKGLERROR
				glTexEnvf(GL_TEXTURE_ENV, GL_ALPHA_SCALE, 1.0f);
CHECKGLERROR
			}
			else
			{
				glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
CHECKGLERROR
			}

			qglClientActiveTexture(GL_TEXTURE0_ARB + (clientunit = i));
CHECKGLERROR
			glTexCoordPointer(2, GL_FLOAT, sizeof(buf_texcoord_t), buf_texcoord[i]);
CHECKGLERROR
			glEnableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
		}
	}
	else
	{
		glBindTexture(GL_TEXTURE_2D, (texture[0] = 0));
CHECKGLERROR
		glDisable(GL_TEXTURE_2D);
CHECKGLERROR
		glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
CHECKGLERROR

		glTexCoordPointer(2, GL_FLOAT, sizeof(buf_texcoord_t), buf_texcoord[0]);
CHECKGLERROR
		glEnableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
	}

	// lock as early as possible
	GL_LockArray(0, currentvertex);
CHECKGLERROR

	for (k = 0;k < currentmesh;)
	{
		mesh = &buf_mesh[k];

		if (backendunits > 1)
		{
//			int topunit = 0;
			for (i = 0;i < backendunits;i++)
			{
				if (texture[i] != mesh->textures[i])
				{
					if (unit != i)
					{
						qglActiveTexture(GL_TEXTURE0_ARB + (unit = i));
CHECKGLERROR
					}
					if (texture[i] == 0)
					{
						glEnable(GL_TEXTURE_2D);
CHECKGLERROR
						// have to disable texcoord array on disabled texture
						// units due to NVIDIA driver bug with
						// compiled_vertex_array
						if (clientunit != i)
						{
							qglClientActiveTexture(GL_TEXTURE0_ARB + (clientunit = i));
CHECKGLERROR
						}
						glEnableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
					}
					glBindTexture(GL_TEXTURE_2D, (texture[i] = mesh->textures[i]));
CHECKGLERROR
					if (texture[i] == 0)
					{
						glDisable(GL_TEXTURE_2D);
CHECKGLERROR
						// have to disable texcoord array on disabled texture
						// units due to NVIDIA driver bug with
						// compiled_vertex_array
						if (clientunit != i)
						{
							qglClientActiveTexture(GL_TEXTURE0_ARB + (clientunit = i));
CHECKGLERROR
						}
						glDisableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
					}
				}
				if (texturergbscale[i] != mesh->texturergbscale[i])
				{
					if (unit != i)
					{
						qglActiveTexture(GL_TEXTURE0_ARB + (unit = i));
CHECKGLERROR
					}
					glTexEnvf(GL_TEXTURE_ENV, GL_RGB_SCALE_ARB, (texturergbscale[i] = mesh->texturergbscale[i]));
CHECKGLERROR
				}
//				if (texture[i])
//					topunit = i;
			}
//			if (unit != topunit)
//			{
//				qglActiveTexture(GL_TEXTURE0_ARB + (unit = topunit));
//CHECKGLERROR
//			}
		}
		else
		{
			if (texture[0] != mesh->textures[0])
			{
				if (texture[0] == 0)
				{
					glEnable(GL_TEXTURE_2D);
CHECKGLERROR
					glEnableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
				}
				glBindTexture(GL_TEXTURE_2D, (texture[0] = mesh->textures[0]));
CHECKGLERROR
				if (texture[0] == 0)
				{
					glDisable(GL_TEXTURE_2D);
CHECKGLERROR
					glDisableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
				}
			}
		}
		if (blendfunc1 != mesh->blendfunc1 || blendfunc2 != mesh->blendfunc2)
		{
			blendfunc1 = mesh->blendfunc1;
			blendfunc2 = mesh->blendfunc2;
			glBlendFunc(blendfunc1, blendfunc2);
CHECKGLERROR
			if (blendfunc2 == GL_ZERO)
			{
				if (blendfunc1 == GL_ONE)
				{
					if (blend)
					{
						blend = 0;
						glDisable(GL_BLEND);
CHECKGLERROR
					}
				}
				else
				{
					if (!blend)
					{
						blend = 1;
						glEnable(GL_BLEND);
CHECKGLERROR
					}
				}
			}
			else
			{
				if (!blend)
				{
					blend = 1;
					glEnable(GL_BLEND);
CHECKGLERROR
				}
			}
		}
		if (depthmask != mesh->depthmask)
		{
			depthmask = mesh->depthmask;
			glDepthMask((GLboolean) depthmask);
CHECKGLERROR
		}

		firsttriangle = mesh->firsttriangle;
		triangles = mesh->triangles;
		mesh = &buf_mesh[++k];

		if (meshmerge)
		{
			#if MAX_TEXTUREUNITS != 4
			#error update this code
			#endif
			while (k < currentmesh
				&& mesh->blendfunc1 == blendfunc1
				&& mesh->blendfunc2 == blendfunc2
				&& mesh->depthmask == depthmask
				&& mesh->textures[0] == texture[0]
				&& mesh->textures[1] == texture[1]
				&& mesh->textures[2] == texture[2]
				&& mesh->textures[3] == texture[3]
				&& mesh->texturergbscale[0] == texturergbscale[0]
				&& mesh->texturergbscale[1] == texturergbscale[1]
				&& mesh->texturergbscale[2] == texturergbscale[2]
				&& mesh->texturergbscale[3] == texturergbscale[3])
			{
				triangles += mesh->triangles;
				mesh = &buf_mesh[++k];
			}
		}

		glDrawElements(GL_TRIANGLES, triangles * 3, GL_UNSIGNED_INT, (unsigned int *)&buf_tri[firsttriangle]);
CHECKGLERROR
	}

	currentmesh = 0;
	currenttriangle = 0;
	currentvertex = 0;

	GL_UnlockArray();
CHECKGLERROR

	if (backendunits > 1)
	{
		for (i = backendunits - 1;i >= 0;i--)
		{
			qglActiveTexture(GL_TEXTURE0_ARB + (unit = i));
CHECKGLERROR
			glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
CHECKGLERROR
			if (gl_combine.integer)
			{
				glTexEnvf(GL_TEXTURE_ENV, GL_RGB_SCALE_ARB, 1.0f);
CHECKGLERROR
			}
			if (i > 0)
			{
				glDisable(GL_TEXTURE_2D);
CHECKGLERROR
			}
			else
			{
				glEnable(GL_TEXTURE_2D);
CHECKGLERROR
			}
			glBindTexture(GL_TEXTURE_2D, 0);
CHECKGLERROR

			qglClientActiveTexture(GL_TEXTURE0_ARB + (clientunit = i));
CHECKGLERROR
			glDisableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
		}
	}
	else
	{
		glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
CHECKGLERROR
		glEnable(GL_TEXTURE_2D);
CHECKGLERROR
		glDisableClientState(GL_TEXTURE_COORD_ARRAY);
CHECKGLERROR
	}
	glDisableClientState(GL_COLOR_ARRAY);
CHECKGLERROR
	glDisableClientState(GL_VERTEX_ARRAY);
CHECKGLERROR

	glDisable(GL_BLEND);
CHECKGLERROR
	glDepthMask(true);
CHECKGLERROR
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
CHECKGLERROR
}

void R_Mesh_AddTransparent(void)
{
	int i, j, k;
	float viewdistcompare, centerscaler, dist1, dist2, dist3, center, maxdist;
	buf_vertex_t *vert1, *vert2, *vert3;
	buf_transtri_t *tri;
	buf_mesh_t *mesh;

	// process and add transparent mesh triangles
	if (!currenttranstriangle)
		return;

	// map farclip to 0-4095 list range
	centerscaler = (TRANSDEPTHRES / r_farclip) * (1.0f / 3.0f);
	viewdistcompare = viewdist + 4.0f;

	memset(buf_transtri_list, 0, TRANSDEPTHRES * sizeof(buf_transtri_t *));

	// process in reverse because transtri_list adding code is in reverse as well
	k = 0;
	for (j = currenttranstriangle - 1;j >= 0;j--)
	{
		tri = &buf_transtri[j];

		vert1 = &buf_transvertex[tri->index[0]];
		vert2 = &buf_transvertex[tri->index[1]];
		vert3 = &buf_transvertex[tri->index[2]];

		dist1 = DotProduct(vert1->v, vpn);
		dist2 = DotProduct(vert2->v, vpn);
		dist3 = DotProduct(vert3->v, vpn);

		maxdist = max(dist1, max(dist2, dist3));
		if (maxdist < viewdistcompare)
			continue;

		center = (dist1 + dist2 + dist3) * centerscaler - viewdist;
#if SLOWMATH
		i = (int) center;
		i = bound(0, i, (TRANSDEPTHRES - 1));
#else
		if (center < 0.0f)
			center = 0.0f;
		center += 8388608.0f;
		i = *((long *)&center) & 0x7FFFFF;
		i = min(i, (TRANSDEPTHRES - 1));
#endif
		tri->next = buf_transtri_list[i];
		buf_transtri_list[i] = tri;
		k++;
	}

	if (currentmesh + k > max_meshs || currenttriangle + k > max_batch || currentvertex + currenttransvertex > max_verts)
		R_Mesh_Render();

	// note: can't batch these because they can be rendered in any order
	// there can never be more transparent triangles than fit in main buffers
	memcpy(&buf_vertex[currentvertex], &buf_transvertex[0], currenttransvertex * sizeof(buf_vertex_t));
	if (floatcolors)
		memcpy(&buf_fcolor[currentvertex], &buf_transfcolor[0], currenttransvertex * sizeof(buf_fcolor_t));
	else
		memcpy(&buf_fcolor[currentvertex], &buf_transbcolor[0], currenttransvertex * sizeof(buf_bcolor_t));
	for (i = 0;i < backendunits;i++)
		memcpy(&buf_texcoord[i][currentvertex], &buf_transtexcoord[i][0], currenttransvertex * sizeof(buf_texcoord_t));

	for (j = TRANSDEPTHRES - 1;j >= 0;j--)
	{
		if ((tri = buf_transtri_list[j]))
		{
			while(tri)
			{
				mesh = &buf_mesh[currentmesh++];
				*mesh = *tri->mesh; // copy mesh properties
				buf_tri[currenttriangle].index[0] = tri->index[0] + currentvertex;
				buf_tri[currenttriangle].index[1] = tri->index[1] + currentvertex;
				buf_tri[currenttriangle].index[2] = tri->index[2] + currentvertex;
				mesh->firsttriangle = currenttriangle++;
				mesh->triangles = 1;
				tri = tri->next;
			}
		}
	}
	currentvertex += currenttransvertex;
	currenttransmesh = 0;
	currenttranstriangle = 0;
	currenttransvertex = 0;
}

void R_Mesh_Draw(const rmeshinfo_t *m)
{
	static int i, j, *index, overbright;
	static float c, *in, scaler, cr, cg, cb, ca;
	static buf_mesh_t *mesh;
	static buf_vertex_t *vert;
	static buf_fcolor_t *fcolor;
	static buf_bcolor_t *bcolor;
	static buf_texcoord_t *texcoord[MAX_TEXTUREUNITS];
	static buf_transtri_t *tri;
	static byte br, bg, bb, ba;

	if (m->index == NULL
	 || !m->numtriangles
	 || m->vertex == NULL
	 || !m->numverts)
	 	return;

	if (!backendactive)
		Sys_Error("R_DrawMesh: called when backend is not active\n");

	if (m->transparent)
	{
		if (currenttransmesh >= max_meshs || (currenttranstriangle + m->numtriangles) > max_meshs || (currenttransvertex + m->numverts) > max_verts)
		{
			if (!transranout)
			{
				Con_Printf("R_DrawMesh: ran out of room for transparent meshs\n");
				transranout = true;
			}
			return;
		}

		vert = &buf_transvertex[currenttransvertex];
		fcolor = &buf_transfcolor[currenttransvertex];
		bcolor = &buf_transbcolor[currenttransvertex];
		for (i = 0;i < backendunits;i++)
			texcoord[i] = &buf_transtexcoord[i][currenttransvertex];
	}
	else
	{
		if (m->numtriangles > max_meshs || m->numverts > max_verts)
		{
			Con_Printf("R_DrawMesh: mesh too big for buffers\n");
			return;
		}

		if (currentmesh >= max_meshs || (currenttriangle + m->numtriangles) > max_batch || (currentvertex + m->numverts) > max_verts)
			R_Mesh_Render();

		vert = &buf_vertex[currentvertex];
		fcolor = &buf_fcolor[currentvertex];
		bcolor = &buf_bcolor[currentvertex];
		for (i = 0;i < backendunits;i++)
			texcoord[i] = &buf_texcoord[i][currentvertex];
	}

	// vertex array code is shared for transparent and opaque meshs

	for (i = 0, in = m->vertex;i < m->numverts;i++, (int)in += m->vertexstep)
	{
		vert[i].v[0] = in[0];
		vert[i].v[1] = in[1];
		vert[i].v[2] = in[2];
		// push out farclip based on vertices encountered
		c = DotProduct(vert[i].v, vpn);
		if (meshfarclip < c)
			meshfarclip = c;
	}

	scaler = 1;
	if (m->blendfunc2 == GL_SRC_COLOR)
	{
		if (m->blendfunc1 == GL_DST_COLOR) // 2x modulate with framebuffer
			scaler *= 0.5f;
	}
	else
	{
		if (m->tex[0])
		{
			overbright = gl_combine.integer;
			if (overbright)
				scaler *= 0.25f;
		}
		if (lighthalf)
			scaler *= 0.5f;
	}

	if (floatcolors)
	{
		if (m->color)
		{
			for (i = 0, in = m->color;i < m->numverts;i++, (int)in += m->colorstep)
			{
				fcolor[i].c[0] = in[0] * scaler;
				fcolor[i].c[1] = in[1] * scaler;
				fcolor[i].c[2] = in[2] * scaler;
				fcolor[i].c[3] = in[3];
			}
		}
		else
		{
			cr = m->cr * scaler;
			cg = m->cg * scaler;
			cb = m->cb * scaler;
			ca = m->ca;
			for (i = 0;i < m->numverts;i++)
			{
				fcolor[i].c[0] = cr;
				fcolor[i].c[1] = cg;
				fcolor[i].c[2] = cb;
				fcolor[i].c[3] = ca;
			}
		}
	}
	else
	{
		if (m->color)
		{
			for (i = 0, in = m->color;i < m->numverts;i++, (int)in += m->colorstep)
			{
				// shift float to have 8bit fraction at base of number,
				// then read as integer and kill float bits...
				c = in[0] * scaler + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;bcolor[i].c[0] = (byte) j;
				c = in[1] * scaler + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;bcolor[i].c[1] = (byte) j;
				c = in[2] * scaler + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;bcolor[i].c[2] = (byte) j;
				c = in[3]          + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;bcolor[i].c[3] = (byte) j;
			}
		}
		else
		{
			c = in[0] * scaler + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;br = (byte) j;
			c = in[1] * scaler + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;bg = (byte) j;
			c = in[2] * scaler + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;bb = (byte) j;
			c = in[3]          + 32768.0f;j = (*((long *)&c) & 0x7FFFFF);if (j > 255) j = 255;ba = (byte) j;
			for (i = 0;i < m->numverts;i++)
			{
				bcolor[i].c[0] = br;
				bcolor[i].c[1] = bg;
				bcolor[i].c[2] = bb;
				bcolor[i].c[3] = ba;
			}
		}
	}

	for (j = 0;j < MAX_TEXTUREUNITS && m->tex[j];j++)
	{
		if (j >= backendunits)
			Sys_Error("R_DrawMesh: texture %i supplied when there are only %i texture units\n", j + 1, backendunits);
		for (i = 0, in = m->texcoords[j];i < m->numverts;i++, (int)in += m->texcoordstep[j])
		{
			texcoord[j][i].t[0] = in[0];
			texcoord[j][i].t[1] = in[1];
		}
	}
	for (;j < backendunits;j++)
	{
		for (i = 0;i < m->numverts;i++)
		{
			texcoord[j][i].t[0] = 0;
			texcoord[j][i].t[1] = 0;
		}
	}

	if (m->transparent)
	{
		// transmesh is only for storage of tranparent meshs until they
		// are inserted into the main mesh array
		mesh = &buf_transmesh[currenttransmesh++];
		mesh->blendfunc1 = m->blendfunc1;
		mesh->blendfunc2 = m->blendfunc2;
		mesh->depthmask = false;
		j = -1;
		for (i = 0;i < backendunits;i++)
		{
			if ((mesh->textures[i] = m->tex[i]))
				j = i;
			mesh->texturergbscale[i] = m->texrgbscale[i];
			if (mesh->texturergbscale[i] != 1 && mesh->texturergbscale[i] != 2 && mesh->texturergbscale[i] != 4)
				mesh->texturergbscale[i] = 1;
		}
		if (overbright && j >= 0)
			mesh->texturergbscale[j] = 4;

		// transparent meshs are broken up into individual triangles which can
		// be sorted by depth
		index = m->index;
		for (i = 0;i < m->numtriangles;i++)
		{
			tri = &buf_transtri[currenttranstriangle++];
			tri->mesh = mesh;
			tri->index[0] = *index++ + currenttransvertex;
			tri->index[1] = *index++ + currenttransvertex;
			tri->index[2] = *index++ + currenttransvertex;
		}
		currenttransvertex += m->numverts;
	}
	else
	{
		mesh = &buf_mesh[currentmesh++];
		mesh->blendfunc1 = m->blendfunc1;
		mesh->blendfunc2 = m->blendfunc2;
		mesh->depthmask = (m->blendfunc2 == GL_ZERO || m->depthwrite);
		mesh->firsttriangle = currenttriangle;
		mesh->triangles = m->numtriangles;
		j = -1;
		for (i = 0;i < backendunits;i++)
		{
			if ((mesh->textures[i] = m->tex[i]))
				j = i;
			mesh->texturergbscale[i] = m->texrgbscale[i];
			if (mesh->texturergbscale[i] != 1 && mesh->texturergbscale[i] != 2 && mesh->texturergbscale[i] != 4)
				mesh->texturergbscale[i] = 1;
		}
		if (overbright && j >= 0)
			mesh->texturergbscale[j] = 4;

		// opaque meshs are rendered directly
		index = (int *)&buf_tri[currenttriangle];
		for (i = 0;i < m->numtriangles * 3;i++)
			index[i] = m->index[i] + currentvertex;
		currenttriangle += m->numtriangles;
		currentvertex += m->numverts;
	}

	c_meshtris += m->numtriangles;
}

void R_Mesh_DrawPolygon(rmeshinfo_t *m, int numverts)
{
	m->index = polyindexarray;
	m->numverts = numverts;
	m->numtriangles = numverts - 2;
	if (m->numtriangles < 1)
	{
		Con_Printf("R_Mesh_DrawPolygon: invalid vertex count\n");
		return;
	}
	if (m->numtriangles >= 256)
	{
		Con_Printf("R_Mesh_DrawPolygon: only up to 256 triangles (258 verts) supported\n");
		return;
	}
	R_Mesh_Draw(m);
}