/*
 * 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.
 *
 */

#include "header/local.h"

#define TURBSCALE ( 256.0 / ( 2 * M_PI ) )
#define SUBDIVIDE_SIZE  64
#define ON_EPSILON      0.1 /* point on plane side epsilon */
#define MAX_CLIP_VERTS  64      

extern model_t *loadmodel;
char skyname [ MAX_QPATH ];
float skyrotate;
vec3_t skyaxis;
image_t *sky_images [ 6 ];
msurface_t  *warpface;
int skytexorder [ 6 ] = { 0, 2, 1, 3, 4, 5 };

/* 3dstudio environment map names */
char    *suf [ 6 ] = { "rt", "bk", "lf", "ft", "up", "dn" }; 

float r_turbsin[] = {
#include "constants/warpsin.h"
};

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;

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 */
};

int vec_to_st [ 6 ] [ 3 ] = {
	{ -2, 3, 1 },
	{ 2, 3, -1 },

	{ 1, 3, 2 },
	{ -1, 3, -2 },

	{ -2, -1, 3 },
	{ -2, 1, -3 }
};

float skymins [ 2 ] [ 6 ], skymaxs [ 2 ] [ 6 ];
float sky_min, sky_max;
                  
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 ] ) );
}

/*
 * 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 ] );
}

/*
 * 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 ];

			s = os + r_turbsin [ (int) ( ( ot * 0.125 + r_newrefdef.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();
	}
}

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;
		}
	}
}

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 )
	{
		ri.Sys_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 );
}

void
R_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 );
	}
}

void
R_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 * 2300;
	b [ 1 ] = t * 2300;
	b [ 2 ] = 2300;

	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 );
}

void
R_DrawSkyBox ( void )
{
	int i;

	if ( skyrotate )
	{   /* check for no sky at all */
		for ( i = 0; i < 6; i++ )
		{
			if ( ( skymins [ 0 ] [ i ] < skymaxs [ 0 ] [ i ] ) &&
				 ( skymins [ 1 ] [ i ] < skymaxs [ 1 ] [ i ] ) )
			{
				break;
			}
		}

		if ( i == 6 )
		{
			return; /* nothing visible */
		}
	}

	qglPushMatrix();
	qglTranslatef( r_origin [ 0 ], r_origin [ 1 ], r_origin [ 2 ] );
	qglRotatef( r_newrefdef.time * skyrotate, skyaxis [ 0 ], skyaxis [ 1 ], skyaxis [ 2 ] );

	for ( i = 0; i < 6; i++ )
	{
		if ( skyrotate )
		{ 
			skymins [ 0 ] [ i ] = -1;
			skymins [ 1 ] [ i ] = -1;
			skymaxs [ 0 ] [ i ] = 1;
			skymaxs [ 1 ] [ i ] = 1;
		}

		if ( ( skymins [ 0 ] [ i ] >= skymaxs [ 0 ] [ i ] ) ||
			 ( skymins [ 1 ] [ i ] >= skymaxs [ 1 ] [ i ] ) )
		{
			continue;
		}

		R_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();
}

void
R_SetSky ( char *name, float rotate, vec3_t axis )
{
	int i;
	char pathname [ MAX_QPATH ];

	strncpy( skyname, name, sizeof ( skyname ) - 1 );
	skyrotate = rotate;
	VectorCopy( axis, skyaxis );

	for ( i = 0; i < 6; i++ )
	{
		Com_sprintf( pathname, sizeof ( pathname ), "env/%s%s.tga", skyname, suf [ i ] );

		sky_images [ i ] = R_FindImage( pathname, it_sky );

		if ( !sky_images [ i ] )
		{
			sky_images [ i ] = r_notexture;
		}

		sky_min = 1.0 / 512;
		sky_max = 511.0 / 512;
	}
}