/*
Copyright (C) 1996-1997 Id Software, Inc.
Copyright (C) 2007 Peter Mackay and Chris Swindle.

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

*/
// gl_mesh.c: triangle model functions

#include <string.h>

extern "C"
{
#include "../quakedef.h"
}

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

ALIAS MODEL DISPLAY LIST GENERATION

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

model_t		*aliasmodel;
aliashdr_t	*paliashdr;

int	used[8192];

// the command list holds counts and s/t values that are valid for
// every frame
int		commands[8192];
int		numcommands;

// all frames will have their vertexes rearranged and expanded
// so they are in the order expected by the command list
int		vertexorder[8192];
int		numorder;

int		allverts, alltris;

int		stripverts[128];
int		striptris[128];
int		stripcount;

/*
================
StripLength
================
*/
static int	StripLength (int starttri, int startv)
{
	int			m1, m2;
	int			j;
	mtriangle_t	*last, *check;
	int			k;

	used[starttri] = 2;

	last = &triangles[starttri];

	stripverts[0] = last->vertindex[(startv)%3];
	stripverts[1] = last->vertindex[(startv+1)%3];
	stripverts[2] = last->vertindex[(startv+2)%3];

	striptris[0] = starttri;
	stripcount = 1;

	m1 = last->vertindex[(startv+2)%3];
	m2 = last->vertindex[(startv+1)%3];

	// look for a matching triangle
nexttri:
	for (j=starttri+1, check=&triangles[starttri+1]; j<pheader->numtris; j++, check++)
	{
		if(check->facesfront != last->facesfront)
			continue;
		for(k=0; k<3 ; k++)
		{
			if (check->vertindex[k] != m1)
				continue;
			if (check->vertindex[ (k+1)%3 ] != m2)
				continue;
			// this is the next part of the fan
			// if we can't use this triangle, this tristrip is done
			if (used[j])
				goto done;
			// the new edge
			if (stripcount & 1)
				m2 = check->vertindex[ (k+2)%3 ];
			else
				m1 = check->vertindex[ (k+2)%3 ];

			stripverts[stripcount+2] = check->vertindex[ (k+2)%3 ];
			striptris[stripcount] = j;
			stripcount++;

			used[j] = 2;
			goto nexttri;
		}
	}
done:

	// clear the temp used flags
	for (j=starttri+1 ; j<pheader->numtris ; j++)
		if (used[j] == 2)
			used[j] = 0;

	return stripcount;
}

/*
===========
FanLength
===========
*/
static int	FanLength (int starttri, int startv)
{
	int		m1, m2;
	int		j;
	mtriangle_t	*last, *check;
	int		k;

	used[starttri] = 2;

	last = &triangles[starttri];

	stripverts[0] = last->vertindex[(startv)%3];
	stripverts[1] = last->vertindex[(startv+1)%3];
	stripverts[2] = last->vertindex[(startv+2)%3];

	striptris[0] = starttri;
	stripcount = 1;

	m1 = last->vertindex[(startv+0)%3];
	m2 = last->vertindex[(startv+2)%3];


	// look for a matching triangle
nexttri:
	for (j=starttri+1, check=&triangles[starttri+1] ; j<pheader->numtris ; j++, check++)
	{
		if (check->facesfront != last->facesfront)
			continue;
		for (k=0 ; k<3 ; k++)
		{
			if (check->vertindex[k] != m1)
				continue;
			if (check->vertindex[ (k+1)%3 ] != m2)
				continue;

			// this is the next part of the fan

			// if we can't use this triangle, this tristrip is done
			if (used[j])
				goto done;

			// the new edge
			m2 = check->vertindex[ (k+2)%3 ];

			stripverts[stripcount+2] = m2;
			striptris[stripcount] = j;
			stripcount++;

			used[j] = 2;
			goto nexttri;
		}
	}
done:

	// clear the temp used flags
	for (j=starttri+1 ; j<pheader->numtris ; j++)
		if (used[j] == 2)
			used[j] = 0;

	return stripcount;
}


/*
================
BuildTrisSingleTriGroup
by blubswillrule
because though I do appreciate the ram saving abilities of generating tristrips and fans, I do not enjoy the increased amount of gpu rendering calls due to having to pass each tristrip or trifan inividually
we're going to instead build one continuous array of triangles such that we can pass the entire model in one single draw call.
After testing:
rendering fps gains were negative (due to having more vertices), so let's not use this after all, hehe...
================
*/
/*
static void BuildTris (void)
{
	int		 j, k;
	int		startv;
	float	s, t;
	int		len;
	int		bestverts[3072];//1024
	int		besttris[1024];

	//
	// build tristrips
	//
	
	numorder = 0;
	numcommands = 0;
	memset (used, 0, sizeof(used));
	
	startv = 0;
	
	mtriangle_t *check;
	check = &triangles[0];
	for(j = 0; j < pheader -> numtris; j++,check++)
	{
		besttris[j] = j;
		for(k = 0; k < 3; k++)
		{
			//stripverts[stripcount+2] = check->vertindex[ (k+2)%3 ];
			bestverts[(j * 3) + k] = check->vertindex[k];
		}
	}
	
	len = pheader->numtris * 3;
	commands[numcommands++] = len;
	for (j=0 ; j< len; j++)
	{
		k = bestverts[j];
		vertexorder[numorder++] = k;
		// emit s/t coords into the commands stream
		
		s = stverts[k].s;
		t = stverts[k].t;
		//if (!triangles[besttris[0]].facesfront && stverts[k].onseam)
		//	s += pheader->skinwidth / 2;	// on back side
		s = (s + 0.5) / pheader->skinwidth;
		t = (t + 0.5) / pheader->skinheight;

		*(float *)&commands[numcommands++] = s;
		*(float *)&commands[numcommands++] = t;
	}
	commands[numcommands++] = 0;		// end of list marker
	allverts += len;
	alltris += pheader->numtris;
}
*/


/*
================
BuildTris

Generate a list of trifans or strips
for the model, which holds for all frames
================
*/

static void BuildTris (void)
{
	int		i, j, k;
	int		startv;
	float	s, t;
	int		len, bestlen, besttype;
	int		bestverts[1024];
	int		besttris[1024];
	int		type;

	//
	// build tristrips
	//
	numorder = 0;
	numcommands = 0;
	besttype = 0;
	memset (used, 0, sizeof(used));
	for (i=0 ; i<pheader->numtris ; i++)
	{
		// pick an unused triangle and start the trifan
		if (used[i])
			continue;

		bestlen = 0;
		for (type = 0 ; type < 2 ; type++)
		//	type = 1;
		{
			for (startv =0 ; startv < 3 ; startv++)
			{
				if (type == 1)
					len = StripLength (i, startv);
				else
					len = FanLength (i, startv);
				if (len > bestlen)
				{
					besttype = type;
					bestlen = len;
					for (j=0 ; j<bestlen+2 ; j++)
						bestverts[j] = stripverts[j];
					for (j=0 ; j<bestlen ; j++)
						besttris[j] = striptris[j];
				}
			}
		}

		// mark the tris on the best strip as used
		for (j=0 ; j<bestlen ; j++)
			used[besttris[j]] = 1;

		if (besttype == 1)
			commands[numcommands++] = (bestlen+2);
		else
			commands[numcommands++] = -(bestlen+2);

		for (j=0 ; j<bestlen+2 ; j++)
		{
			// emit a vertex into the reorder buffer
			k = bestverts[j];
			vertexorder[numorder++] = k;

			// emit s/t coords into the commands stream
			s = stverts[k].s;
			t = stverts[k].t;
			if (!triangles[besttris[0]].facesfront && stverts[k].onseam)
				s += pheader->skinwidth / 2;	// on back side
			s = (s + 0.5) / pheader->skinwidth;
			t = (t + 0.5) / pheader->skinheight;

			*(float *)&commands[numcommands++] = s;
			*(float *)&commands[numcommands++] = t;
		}
	}

	commands[numcommands++] = 0;		// end of list marker

	Con_DPrintf ("%3i tri %3i vert %3i cmd\n", pheader->numtris, numorder, numcommands);

	allverts += numorder;
	alltris += pheader->numtris;
}

#if MS2WRITING
/*
================
GL_MakeAliasModelDisplayLists
================
*/
void GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr)
{
	aliasmodel = m;
	paliashdr = hdr;	// (aliashdr_t *)Mod_Extradata (m);

	BuildTris();

	// save the data out

	paliashdr->poseverts = numorder;

	int* cmds = static_cast<int*>(Hunk_Alloc (numcommands * 4));
	paliashdr->commands = (byte *)cmds - (byte *)paliashdr;
	memcpy (cmds, commands, numcommands * 4);

	trivertx_t* verts = static_cast<trivertx_t*>(Hunk_Alloc (paliashdr->numposes * paliashdr->poseverts
		* sizeof(trivertx_t) ));
	paliashdr->posedata = (byte *)verts - (byte *)paliashdr;
	for (int i=0 ; i<paliashdr->numposes ; i++)
		for (int j=0 ; j<numorder ; j++)
			*verts++ = poseverts[i][vertexorder[j]];
}
#else

void ScaleVerts (byte *original, vec3_t scaled)
{
	scaled[0] = (float)original[0] * paliashdr->scale[0] + paliashdr->scale_origin[0];
	scaled[1] = (float)original[1] * paliashdr->scale[1] + paliashdr->scale_origin[1];
	scaled[2] = (float)original[2] * paliashdr->scale[2] + paliashdr->scale_origin[2];
}

/*
================
GL_MakeAliasModelDisplayLists
================
*/
void GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr)
{
	int		i, j;
	int			*cmds;
	trivertx_t	*verts;

	aliasmodel = m;
	paliashdr = hdr;	// (aliashdr_t *)Mod_Extradata (m);


	// Tonik: don't cache anything, because it seems just as fast
	// (if not faster) to rebuild the tris instead of loading them from disk
	
	BuildTris(); // trifans or lists

	// save the data out

	paliashdr->poseverts = numorder;

	cmds = static_cast<int*>(Hunk_Alloc (numcommands * 4));
	paliashdr->commands = (byte *)cmds - (byte *)paliashdr;
	memcpy (cmds, commands, numcommands * 4);

	verts = static_cast<trivertx_t*>(Hunk_Alloc (paliashdr->numposes * paliashdr->poseverts
		* sizeof(trivertx_t)));
	paliashdr->posedata = (byte *)verts - (byte *)paliashdr;
	for (i=0 ; i<paliashdr->numposes ; i++)
		for (j=0 ; j<numorder ; j++)
			*verts++ = poseverts[i][vertexorder[j]];

	// code for elimination of muzzleflashes on viewmodels
	/*if (m->modhint == MOD_WEAPON && qmb_initialized && r_part_muzzleflash.value)
	{
		vec3_t	scaledf0, scaledf1;	// scaled versions of the verts (need to prescale for comparison)
		float	vdiff;				// difference in front to back movement
		qboolean *nodraw;			// true if the vert is a muzzleflash

		// get pointers to the verts
		trivertx_t	*vertsf0 = (trivertx_t *)((byte *)hdr + hdr->posedata);
		trivertx_t	*vertsfi = (trivertx_t *)((byte *)hdr + hdr->posedata);

		// set up the nodraw buffer
		nodraw = static_cast<qboolean*>(malloc (numorder * sizeof(qboolean)));

		// setthese pointers to the 0th and 1st frames
		vertsf0 += hdr->frames[0].firstpose * hdr->poseverts;
		vertsfi += hdr->frames[1].firstpose * hdr->poseverts;

		// now go through them and compare.  we expect that (a) the animation is sensible and there's no major
		// difference between the 2 frames to be expected, and (b) any verts that do exhibit a major difference
		// can be assumed to belong to the muzzleflash
		for (j = 0; j < numorder; j++)
		{
			ScaleVerts (vertsf0->v, scaledf0);
			ScaleVerts (vertsfi->v, scaledf1);

			// get difference in front to back movement
			vdiff = scaledf1[0] - scaledf0[0];

			// if it's above a certain treshold, assume a muzzleflash and mark for nodraw
			// 10 is the approx lowest range of visible front to back in a view model, so that seems reasonable to work with
			if (vdiff > 10)
				nodraw[j] = qtrue;
			else nodraw[j] = qfalse;

			// next set of verts
			vertsf0++;
			vertsfi++;
		}

		// copy the relevant verts from the first frame to every other frame
		for (i = 1; i < paliashdr->numframes; i++)
		{
			// get pointers to the verts again
			vertsf0 = (trivertx_t *)((byte *) hdr + hdr->posedata);
			vertsfi = (trivertx_t *)((byte *) hdr + hdr->posedata);

			// set these pointers to the 0th and i'th frames
			vertsf0 += hdr->frames[0].firstpose * hdr->poseverts;
			vertsfi += hdr->frames[i].firstpose * hdr->poseverts;

			for (j = 0; j < numorder; j++)
			{
				// copy the verts from frame 0
				if (nodraw[j])
				{
					vertsfi->v[0] = vertsf0->v[0];
					vertsfi->v[1] = vertsf0->v[1];
					vertsfi->v[2] = vertsf0->v[2];
				}

				// next set of verts
				vertsf0++;
				vertsfi++;
			}
		}

		// release the nodraw buffer
		free (nodraw);
	}*/
}
#endif