/*
* Copyright(c) 1997-2001 Id Software, Inc.
* Copyright(c) 2002 The Quakeforge Project.
* Copyright(c) 2006 Quetoo.
*
* 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.
*/

#include "video.h"
#include "gl_warp.h"

extern	model_t *loadmodel;

char skyname[MAX_QPATH];
image_t *sky_images[6];

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)
		Com_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]);
}

   
/*
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_viewdef.time;
	
	if(fa->texinfo->flags & SURF_FLOWING)
		scroll = -64 *((r_viewdef.time * 0.5) -(int)(r_viewdef.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];
			
			s = os + r_turbsin[(int)((ot * 0.125 + r_viewdef.time) * TURBSCALE) & 255];
			
			s += scroll;
			s *=(1.0 / 64);
			
			t = ot + r_turbsin[(int)((os * 0.125 + rdt) * TURBSCALE) & 255];
			
			t *=(1.0 / 64);
			
			qglTexCoord2f(s, t);
			qglVertex3fv(v);
		}
		qglEnd();
	}
}




vec3_t skyclip[6] = {
						{1, 1, 0},
						{1, -1, 0},
						{0, -1, 1},
						{0, 1, 1},
						{1, 0, 1},
						{ -1, 0, 1}
					};
int c_sky;

// 1 = s, 2 = t, 3 = 2048
int st_to_vec[6][3] =
	{
		{3, -1, 2},
		{ -3, 1, 2},
		
		{1, 3, 2},
		{ -1, -3, 2},
		
		{ -2, -1, 3},   // 0 degrees yaw, look straight up
		{2, -1, -3}  // look straight down
		
	//	{-1,2,3},
	//	{1,2,-3}
	};
	
// s = [0]/[2], t = [1]/[2]
int vec_to_st[6][3] =
	{
		{ -2, 3, 1},
		{2, 3, -1},
		
		{1, 3, 2},
		{ -1, 3, -2},
		
		{ -2, -1, 3},
		{ -2, 1, -3}
		
	//	{-1,2,3},
	//	{1,2,-3}
	};
	
float skymins[2][6], skymaxs[2][6];
float sky_min, sky_max;

void DrawSkyPolygon(int nump, vec3_t vecs){
	int i, j;
	vec3_t v, av;
	float s, t, dv;
	int axis;
	float *vp;
	
	c_sky++;
	
	// decide which face it maps to
	VectorCopy(vec3_origin, v);
	for(i = 0, vp = vecs; i < nump; i++, vp += 3){
		VectorAdd(vp, v, v);
	}
	
	av[0] = fabs(v[0]);
	av[1] = fabs(v[1]);
	av[2] = fabs(v[2]);
	
	if(av[0] > av[1] && av[0] > av[2]){
		if(v[0] < 0) axis = 1;
		else axis = 0;
	} else if(av[1] > av[2] && av[1] > av[0]){
		if(v[1] < 0) axis = 3;
		else axis = 2;
	} else {
		if(v[2] < 0) axis = 5;
		else axis = 4;
	}
	
	// project new texture coords
	for(i = 0; i < nump; i++, vecs += 3){
		j = vec_to_st[axis][2];
		if(j > 0)
			dv = vecs[j - 1];
		else
			dv = -vecs[ -j - 1];
		if(dv < 0.001)
			continue;  // don't divide by zero
		j = vec_to_st[axis][0];
		if(j < 0)
			s = -vecs[ -j - 1] / dv;
		else
			s = vecs[j - 1] / dv;
		j = vec_to_st[axis][1];
		if(j < 0)
			t = -vecs[ -j - 1] / dv;
		else
			t = vecs[j - 1] / dv;
			
		if(s < skymins[0][axis])
			skymins[0][axis] = s;
		if(t < skymins[1][axis])
			skymins[1][axis] = t;
		if(s > skymaxs[0][axis])
			skymaxs[0][axis] = s;
		if(t > skymaxs[1][axis])
			skymaxs[1][axis] = t;
	}
}

#define ON_EPSILON		0.1  // point on plane side epsilon
#define MAX_CLIP_VERTS	64
void ClipSkyPolygon(int nump, vec3_t vecs, int stage){
	float *norm;
	float *v;
	qboolean	front, back;
	float d, e;
	float dists[MAX_CLIP_VERTS];
	int sides[MAX_CLIP_VERTS];
	vec3_t newv[2][MAX_CLIP_VERTS];
	int newc[2];
	int i, j;
	
	if(nump > MAX_CLIP_VERTS - 2)
		Com_Error(ERR_DROP, "ClipSkyPolygon: MAX_CLIP_VERTS");
	if(stage == 6){  // fully clipped, so draw it
		DrawSkyPolygon(nump, vecs);
		return;
	}
	
	front = back = false;
	norm = skyclip[stage];
	for(i = 0, v = vecs; i < nump; i++, v += 3){
		d = DotProduct(v, norm);
		if(d > ON_EPSILON){
			front = true;
			sides[i] = SIDE_FRONT;
		} else if(d < -ON_EPSILON){
			back = true;
			sides[i] = SIDE_BACK;
		} else
			sides[i] = SIDE_ON;
		dists[i] = d;
	}
	
	if(!front || !back){  // not clipped
		ClipSkyPolygon(nump, vecs, stage + 1);
		return;
	}
	
	// clip it
	sides[i] = sides[0];
	dists[i] = dists[0];
	VectorCopy(vecs,(vecs +(i*3)));
	newc[0] = newc[1] = 0;
	
	for(i = 0, v = vecs; i < nump; i++, v += 3){
		switch(sides[i]){
			case SIDE_FRONT:
				VectorCopy(v, newv[0][newc[0]]);
				newc[0]++;
				break;
			case SIDE_BACK:
				VectorCopy(v, newv[1][newc[1]]);
				newc[1]++;
				break;
			case SIDE_ON:
				VectorCopy(v, newv[0][newc[0]]);
				newc[0]++;
				VectorCopy(v, newv[1][newc[1]]);
				newc[1]++;
				break;
		}
		
		if(sides[i] == SIDE_ON || sides[i + 1] == SIDE_ON || sides[i + 1] == sides[i])
			continue;
			
		d = dists[i] /(dists[i] - dists[i + 1]);
		for(j = 0; j < 3; j++){
			e = v[j] + d *(v[j + 3] - v[j]);
			newv[0][newc[0]][j] = e;
			newv[1][newc[1]][j] = e;
		}
		newc[0]++;
		newc[1]++;
	}
	
	// continue
	ClipSkyPolygon(newc[0], newv[0][0], stage + 1);
	ClipSkyPolygon(newc[1], newv[1][0], stage + 1);
}

/*
GL_AddSkySurface
*/
void GL_AddSkySurface(msurface_t *fa){
	int i;
	vec3_t verts[MAX_CLIP_VERTS];
	glpoly_t *p;
	
	// calculate vertex values for sky box
	for(p = fa->polys; p; p = p->next){
		for(i = 0; i < p->numverts; i++){
			VectorSubtract(p->verts[i], r_origin, verts[i]);
		}
		ClipSkyPolygon(p->numverts, verts[0], 0);
	}
}


/*
GL_ClearSkyBox
*/
void GL_ClearSkyBox(void){
	int i;
	
	for(i = 0; i < 6; i++){
		skymins[0][i] = skymins[1][i] = 9999;
		skymaxs[0][i] = skymaxs[1][i] = -9999;
	}
}


void MakeSkyVec(float s, float t, int axis){
	vec3_t v, b;
	int j, k;
	
	b[0] = s * skydistance->value;
	b[1] = t * skydistance->value;
	b[2] = skydistance->value;
	
	for(j = 0; j < 3; j++){
		k = st_to_vec[axis][j];
		if(k < 0)
			v[j] = -b[ -k - 1];
		else
			v[j] = b[k - 1];
	}
	
	// avoid bilerp seam
	s =(s + 1) * 0.5;
	t =(t + 1) * 0.5;
	
	if(s < sky_min)
		s = sky_min;
	else if(s > sky_max)
		s = sky_max;
	if(t < sky_min)
		t = sky_min;
	else if(t > sky_max)
		t = sky_max;
		
	t = 1.0 - t;
	qglTexCoord2f(s, t);
	qglVertex3fv(v);
}

/*
GL_DrawSkyBox
*/
int skytexorder[6] = {0, 2, 1, 3, 4, 5};
void GL_DrawSkyBox(void){
	int i;
	
	qglPushMatrix();
	qglTranslatef(r_origin[0], r_origin[1], r_origin[2]);
	
	for(i = 0; i < 6; i++){
		
		if(skymins[0][i] >= skymaxs[0][i]
				|| skymins[1][i] >= skymaxs[1][i])
			continue;
			
		GL_Bind(sky_images[skytexorder[i]]->texnum);
		
		qglBegin(GL_QUADS);
		MakeSkyVec(skymins[0][i], skymins[1][i], i);
		MakeSkyVec(skymins[0][i], skymaxs[1][i], i);
		MakeSkyVec(skymaxs[0][i], skymaxs[1][i], i);
		MakeSkyVec(skymaxs[0][i], skymins[1][i], i);
		qglEnd();
	}
	qglPopMatrix();
}


/*
GL_SetSky
*/ 
// 3dstudio environment map names
char *suf[6] = {"rt", "bk", "lf", "ft", "up", "dn"};
void GL_SetSky(char *name){
	int i;
	char pathname[MAX_QPATH];
	
	strncpy(skyname, name, sizeof(skyname) - 1);
	
	for(i = 0; i < 6; i++){
		if(gl_skymip->value)
			gl_picmip->value++;
			
		Com_sprintf(pathname, sizeof(pathname), "env/%s%s.tga", skyname, suf[i]);
		
		sky_images[i] = GL_FindImage(pathname, it_sky);
		if(!sky_images[i])
			sky_images[i] = r_notexture;
			
		if(gl_skymip->value){  // take less memory
			gl_picmip->value--;
			sky_min = 1.0 / 256;
			sky_max = 255.0 / 256;
		} else {
			sky_min = 1.0 / 512;
			sky_max = 511.0 / 512;
		}
	}
}