/*
Copyright (C) 1996-1997 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 "quakedef.h"

float TraceLine (vec3_t start, vec3_t end, vec3_t impact, vec3_t normal);

#define MAX_EXPLOSIONS 64
#define EXPLOSIONGRID 16
#define EXPLOSIONVERTS ((EXPLOSIONGRID+1)*(EXPLOSIONGRID+1))
#define EXPLOSIONTRIS (EXPLOSIONVERTS*2)
#define EXPLOSIONSTARTRADIUS (0.0f)
#define EXPLOSIONSTARTVELOCITY (500.0f)
#define EXPLOSIONFADESTART (1.5f)
#define EXPLOSIONFADERATE (6.0f)

vec3_t explosionspherevert[EXPLOSIONVERTS];
vec3_t explosionspherevertvel[EXPLOSIONVERTS];
float explosiontexcoords[EXPLOSIONVERTS][2];
int explosiontris[EXPLOSIONTRIS][3];
int explosionnoiseindex[EXPLOSIONVERTS];
vec3_t explosionpoint[EXPLOSIONVERTS];

typedef struct explosion_s
{
	float starttime;
	float alpha;
	vec3_t vert[EXPLOSIONVERTS];
	vec3_t vertvel[EXPLOSIONVERTS];
}
explosion_t;

explosion_t explosion[128];

rtexture_t	*explosiontexture;
rtexture_t	*explosiontexturefog;

cvar_t r_explosionclip = {"r_explosionclip", "0", true};
cvar_t r_drawexplosions = {"r_drawexplosions", "1"};

int R_ExplosionVert(int column, int row)
{
	int i;
	float a, b, c;
	i = row * (EXPLOSIONGRID + 1) + column;
	a = row * M_PI * 2 / EXPLOSIONGRID;
	b = column * M_PI * 2 / EXPLOSIONGRID;
	c = cos(b);
	explosionpoint[i][0] = cos(a) * c;
	explosionpoint[i][1] = sin(a) * c;
	explosionpoint[i][2] = -sin(b);
	explosionnoiseindex[i] = (row & (EXPLOSIONGRID - 1)) * EXPLOSIONGRID + (column & (EXPLOSIONGRID - 1));
	explosiontexcoords[i][0] = (float) column / (float) EXPLOSIONGRID;
	explosiontexcoords[i][1] = (float) row / (float) EXPLOSIONGRID;
	return i;
}

void r_explosion_start(void)
{
	int x, y;
	byte noise1[128][128], noise2[128][128], data[128][128][4];
	fractalnoise(&noise1[0][0], 128, 2);
	fractalnoise(&noise2[0][0], 128, 2);
	for (y = 0;y < 128;y++)
	{
		for (x = 0;x < 128;x++)
		{
			int j, r, g, b, a;
			j = noise1[y][x] * 3 - 128;
			r = (j * 512) / 256;
			g = (j * 256) / 256;
			b = (j * 128) / 256;
			a = noise2[y][x];
			data[y][x][0] = bound(0, r, 255);
			data[y][x][1] = bound(0, g, 255);
			data[y][x][2] = bound(0, b, 255);
			data[y][x][3] = bound(0, a, 255);
		}
	}
	explosiontexture = R_LoadTexture ("explosiontexture", 128, 128, &data[0][0][0], TEXF_MIPMAP | TEXF_ALPHA | TEXF_RGBA | TEXF_PRECACHE);
	for (y = 0;y < 128;y++)
		for (x = 0;x < 128;x++)
			data[y][x][0] = data[y][x][1] = data[y][x][2] = 255;
	explosiontexturefog = R_LoadTexture ("explosiontexturefog", 128, 128, &data[0][0][0], TEXF_MIPMAP | TEXF_ALPHA | TEXF_RGBA | TEXF_PRECACHE);
}

void r_explosion_shutdown(void)
{
}

void r_explosion_newmap(void)
{
	memset(explosion, 0, sizeof(explosion));
}

void R_Explosion_Init(void)
{
	int i, x, y;
	i = 0;
	for (y = 0;y < EXPLOSIONGRID;y++)
	{
		for (x = 0;x < EXPLOSIONGRID;x++)
		{
			explosiontris[i][0] = R_ExplosionVert(x    , y    );
			explosiontris[i][1] = R_ExplosionVert(x + 1, y    );
			explosiontris[i][2] = R_ExplosionVert(x    , y + 1);
			i++;
			explosiontris[i][0] = R_ExplosionVert(x + 1, y    );
			explosiontris[i][1] = R_ExplosionVert(x + 1, y + 1);
			explosiontris[i][2] = R_ExplosionVert(x    , y + 1);
			i++;
		}
	}
	for (i = 0;i < EXPLOSIONVERTS;i++)
	{
		explosionspherevert[i][0] = explosionpoint[i][0] * EXPLOSIONSTARTRADIUS;
		explosionspherevert[i][1] = explosionpoint[i][1] * EXPLOSIONSTARTRADIUS;
		explosionspherevert[i][2] = explosionpoint[i][2] * EXPLOSIONSTARTRADIUS;
		explosionspherevertvel[i][0] = explosionpoint[i][0] * EXPLOSIONSTARTVELOCITY;
		explosionspherevertvel[i][1] = explosionpoint[i][1] * EXPLOSIONSTARTVELOCITY;
		explosionspherevertvel[i][2] = explosionpoint[i][2] * EXPLOSIONSTARTVELOCITY;
	}

	Cvar_RegisterVariable(&r_explosionclip);
	Cvar_RegisterVariable(&r_drawexplosions);

	R_RegisterModule("R_Explosions", r_explosion_start, r_explosion_shutdown, r_explosion_newmap);
}

void R_NewExplosion(vec3_t org)
{
	int i, j;
	float dist;
	byte noise[EXPLOSIONGRID*EXPLOSIONGRID];
	fractalnoise(noise, EXPLOSIONGRID, 2);
	for (i = 0;i < MAX_EXPLOSIONS;i++)
	{
		if (explosion[i].alpha <= 0.0f)
		{
			explosion[i].alpha = EXPLOSIONFADESTART;
			for (j = 0;j < EXPLOSIONVERTS;j++)
			{
				dist = noise[explosionnoiseindex[j]] * (1.0f / 512.0f) + 0.5;
				explosion[i].vert[j][0] = explosionspherevert[j][0] * dist + org[0];
				explosion[i].vert[j][1] = explosionspherevert[j][1] * dist + org[1];
				explosion[i].vert[j][2] = explosionspherevert[j][2] * dist + org[2];
				explosion[i].vertvel[j][0] = explosionspherevertvel[j][0] * dist;
				explosion[i].vertvel[j][1] = explosionspherevertvel[j][1] * dist;
				explosion[i].vertvel[j][2] = explosionspherevertvel[j][2] * dist;
			}
			break;
		}
	}
}

void R_DrawExplosion(explosion_t *e)
{
	int i, index, *indexlist = &explosiontris[0][0], alpha = bound(0, e->alpha * 128.0f, 128), texnum, fogtexnum;
	float s, t;
//	s = cl.time * 1;
//	t = cl.time * 0.75;
//	s -= (int) s;
//	t -= (int) t;
	s = 0;
	t = 0;
	/*
	glColor4f(1,1,1,e->alpha);
	glDisable(GL_TEXTURE_2D);
//	glBindTexture(GL_TEXTURE_2D, explosiontexture);
	glVertexPointer(3, GL_FLOAT, 0, (float *) &e->vert[0][0]);
//	glTexCoordPointer(2, GL_FLOAT, 0, (float *) &explosiontexcoords[0][0]);
	glEnableClientState(GL_VERTEX_ARRAY);
//	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
	glDrawElements(GL_TRIANGLES, EXPLOSIONTRIS, GL_UNSIGNED_INT, indexlist);
//	glDisableClientState(GL_TEXTURE_COORD_ARRAY);
	glDisableClientState(GL_VERTEX_ARRAY);
	glEnable(GL_TEXTURE_2D);
	*/
	texnum = R_GetTexture(explosiontexture);
	fogtexnum = R_GetTexture(explosiontexturefog);
	for (i = 0;i < EXPLOSIONTRIS;i++)
	{
		transpolybegin(texnum, 0, fogtexnum, TPOLYTYPE_ALPHA);
		index = *indexlist++;transpolyvert(e->vert[index][0], e->vert[index][1], e->vert[index][2], explosiontexcoords[index][0] + s, explosiontexcoords[index][1] + t, 255, 255, 255, alpha);
		index = *indexlist++;transpolyvert(e->vert[index][0], e->vert[index][1], e->vert[index][2], explosiontexcoords[index][0] + s, explosiontexcoords[index][1] + t, 255, 255, 255, alpha);
		index = *indexlist++;transpolyvert(e->vert[index][0], e->vert[index][1], e->vert[index][2], explosiontexcoords[index][0] + s, explosiontexcoords[index][1] + t, 255, 255, 255, alpha);
		transpolyend();
	}
}

void R_MoveExplosion(explosion_t *e, float frametime)
{
	int i;
	vec3_t end;
	e->alpha -= frametime * EXPLOSIONFADERATE;
	for (i = 0;i < EXPLOSIONVERTS;i++)
	{
		if (e->vertvel[i][0] || e->vertvel[i][1] || e->vertvel[i][2])
		{
			end[0] = e->vert[i][0] + frametime * e->vertvel[i][0];
			end[1] = e->vert[i][1] + frametime * e->vertvel[i][1];
			end[2] = e->vert[i][2] + frametime * e->vertvel[i][2];
			if (r_explosionclip.value)
			{
				float f, dot;
				vec3_t impact, normal;
				f = TraceLine(e->vert[i], end, impact, normal);
				VectorCopy(impact, e->vert[i]);
				if (f < 1)
				{
					// clip velocity against the wall
					dot = -DotProduct(e->vertvel[i], normal);
					e->vertvel[i][0] += normal[0] * dot;
					e->vertvel[i][1] += normal[1] * dot;
					e->vertvel[i][2] += normal[2] * dot;
				}
			}
			else
			{
				VectorCopy(end, e->vert[i]);
			}
		}
	}
}

void R_MoveExplosions(void)
{
	int i;
	float frametime;
	frametime = cl.time - cl.oldtime;
	for (i = 0;i < MAX_EXPLOSIONS;i++)
	{
		if (explosion[i].alpha > 0.0f)
		{
			if (explosion[i].starttime > cl.time)
			{
				explosion[i].alpha = 0;
				continue;
			}
			R_MoveExplosion(&explosion[i], frametime);
		}
	}
}

void R_DrawExplosions(void)
{
	int i;
	if (!r_drawexplosions.value)
		return;
	for (i = 0;i < MAX_EXPLOSIONS;i++)
	{
		if (explosion[i].alpha > 0.0f)
		{
			R_DrawExplosion(&explosion[i]);
		}
	}
}