/*
Copyright (C) 1997-2001 Id Software, Inc.

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_warp.c -- water polygon subdivision and rendering

#include "gl_local.h"

extern	model_t	*loadmodel;

msurface_t	*warpface;

#define	SUBDIVIDE_SIZE	64
//#define	SUBDIVIDE_SIZE	1024

void BoundPoly (int numverts, float *verts, vec3_t mins, vec3_t maxs)
{
	int		i, j;
	float	*v;

	mins[0] = mins[1] = mins[2] = 9999;
	maxs[0] = maxs[1] = maxs[2] = -9999;
	v = verts;
	for (i=0 ; i<numverts ; i++)
		for (j=0 ; j<3 ; j++, v++)
		{
			if (*v < mins[j])
				mins[j] = *v;
			if (*v > maxs[j])
				maxs[j] = *v;
		}
}

void SubdividePolygon (int numverts, float *verts)
{
	int		i, j, k;
	vec3_t	mins, maxs;
	float	m;
	float	*v;
	vec3_t	front[64], back[64];
	int		f, b;
	float	dist[64];
	float	frac;
	glpoly_t	*poly;
	float	s, t;
	vec3_t	total;
	float	total_s, total_t;

	if (numverts > 60)
		ri.Sys_Error (ERR_DROP, "numverts = %i", numverts);

	BoundPoly (numverts, verts, mins, maxs);

	for (i=0 ; i<3 ; i++)
	{
		m = (mins[i] + maxs[i]) * 0.5;
		m = SUBDIVIDE_SIZE * floor (m/SUBDIVIDE_SIZE + 0.5);
		if (maxs[i] - m < 8)
			continue;
		if (m - mins[i] < 8)
			continue;

		// cut it
		v = verts + i;
		for (j=0 ; j<numverts ; j++, v+= 3)
			dist[j] = *v - m;

		// wrap cases
		dist[j] = dist[0];
		v-=i;
		VectorCopy (verts, v);

		f = b = 0;
		v = verts;
		for (j=0 ; j<numverts ; j++, v+= 3)
		{
			if (dist[j] >= 0)
			{
				VectorCopy (v, front[f]);
				f++;
			}
			if (dist[j] <= 0)
			{
				VectorCopy (v, back[b]);
				b++;
			}
			if (dist[j] == 0 || dist[j+1] == 0)
				continue;
			if ( (dist[j] > 0) != (dist[j+1] > 0) )
			{
				// clip point
				frac = dist[j] / (dist[j] - dist[j+1]);
				for (k=0 ; k<3 ; k++)
					front[f][k] = back[b][k] = v[k] + frac*(v[3+k] - v[k]);
				f++;
				b++;
			}
		}

		SubdividePolygon (f, front[0]);
		SubdividePolygon (b, back[0]);
		return;
	}

	// add a point in the center to help keep warp valid
	poly = Hunk_Alloc (sizeof(glpoly_t) + ((numverts-4)+2) * VERTEXSIZE*sizeof(float));
	poly->next = warpface->polys;
	warpface->polys = poly;
	poly->numverts = numverts+2;
	VectorClear (total);
	total_s = 0;
	total_t = 0;
	for (i=0 ; i<numverts ; i++, verts+= 3)
	{
		VectorCopy (verts, poly->verts[i+1]);
		s = DotProduct (verts, warpface->texinfo->vecs[0]);
		t = DotProduct (verts, warpface->texinfo->vecs[1]);

		total_s += s;
		total_t += t;
		VectorAdd (total, verts, total);

		poly->verts[i+1][3] = s;
		poly->verts[i+1][4] = t;
	}

	VectorScale (total, (1.0/numverts), poly->verts[0]);
	poly->verts[0][3] = total_s/numverts;
	poly->verts[0][4] = total_t/numverts;

	// copy first vertex to last
	memcpy (poly->verts[i+1], poly->verts[1], sizeof(poly->verts[0]));
}

/*
================
GL_SubdivideSurface

Breaks a polygon up along axial 64 unit
boundaries so that turbulent and sky warps
can be done reasonably.
================
*/
void GL_SubdivideSurface (msurface_t *fa)
{
	vec3_t		verts[64];
	int			numverts;
	int			i;
	int			lindex;
	float		*vec;

	warpface = fa;

	//
	// convert edges back to a normal polygon
	//
	numverts = 0;
	for (i=0 ; i<fa->numedges ; i++)
	{
		lindex = loadmodel->surfedges[fa->firstedge + i];

		if (lindex > 0)
			vec = loadmodel->vertexes[loadmodel->edges[lindex].v[0]].position;
		else
			vec = loadmodel->vertexes[loadmodel->edges[-lindex].v[1]].position;
		VectorCopy (vec, verts[numverts]);
		numverts++;
	}

	SubdividePolygon (numverts, verts[0]);
}

//=========================================================



// speed up sin calculations - Ed
float	r_turbsin[] =
{
	#include "warpsin.h"
};
#define TURBSCALE (256.0 / (2 * M_PI))

/*
=============
EmitWaterPolys

Does a water warp on the pre-fragmented glpoly_t chain
=============
*/
void EmitWaterPolys (msurface_t *fa)
{
	glpoly_t	*p, *bp;
	float		*v;
	int			i;
	float		s, t, os, ot;
	float		scroll;
	float		rdt = r_newrefdef.time;

	if (fa->texinfo->flags & SURF_FLOWING)
		scroll = -64 * ( (r_newrefdef.time*0.5) - (int)(r_newrefdef.time*0.5) );
	else
		scroll = 0;
	for (bp=fa->polys ; bp ; bp=bp->next)
	{
		p = bp;

		qglBegin (GL_TRIANGLE_FAN);
		for (i=0,v=p->verts[0] ; i<p->numverts ; i++, v+=VERTEXSIZE)
		{
			os = v[3];
			ot = v[4];

#if !id386
			s = os + r_turbsin[(int)((ot*0.125+r_newrefdef.time) * TURBSCALE) & 255];
#else
			s = os + r_turbsin[Q_ftol( ((ot*0.125+rdt) * TURBSCALE) ) & 255];
#endif
			s += scroll;
			s *= (1.0/64);

#if !id386
			t = ot + r_turbsin[(int)((os*0.125+rdt) * TURBSCALE) & 255];
#else
			t = ot + r_turbsin[Q_ftol( ((os*0.125+rdt) * TURBSCALE) ) & 255];
#endif
			t *= (1.0/64);

			qglTexCoord2f (s, t);
			qglVertex3fv (v);
		}
		qglEnd ();
	}
}
