/*
===========================================================================
Copyright (C) 1999 - 2005, Id Software, Inc.
Copyright (C) 2000 - 2013, Raven Software, Inc.
Copyright (C) 2001 - 2013, Activision, Inc.
Copyright (C) 2013 - 2015, OpenJK contributors

This file is part of the OpenJK source code.

OpenJK is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.

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, see <http://www.gnu.org/licenses/>.
===========================================================================
*/

#include "tr_local.h"

#define	MAX_VERTS_ON_DECAL_POLY	10
#define	MAX_DECAL_POLYS			500

typedef struct decalPoly_s
{
	int					time;
	int					fadetime;
	qhandle_t			shader;
	float				color[4];
	poly_t				poly;
	polyVert_t			verts[MAX_VERTS_ON_DECAL_POLY];
} decalPoly_t;

enum
{
	DECALPOLY_TYPE_NORMAL,
	DECALPOLY_TYPE_FADE,
	DECALPOLY_TYPE_MAX
};

#define		DECAL_FADE_TIME		1000

decalPoly_t*		RE_AllocDecal( int type );

static decalPoly_t	re_decalPolys[DECALPOLY_TYPE_MAX][MAX_DECAL_POLYS];

static int			re_decalPolyHead[DECALPOLY_TYPE_MAX];
static int			re_decalPolyTotal[DECALPOLY_TYPE_MAX];

/*
===================
RE_ClearDecals

This is called to remove all decals from the world
===================
*/
void RE_ClearDecals( void ) {
	memset( re_decalPolys, 0, sizeof(re_decalPolys) );
	memset( re_decalPolyHead, 0, sizeof(re_decalPolyHead) );
	memset( re_decalPolyTotal, 0, sizeof(re_decalPolyTotal) );
}

void R_InitDecals( void ) {
	RE_ClearDecals();
}

void RE_FreeDecal( int type, int index ) {
	if ( !re_decalPolys[type][index].time )
		return;

	if ( type == DECALPOLY_TYPE_NORMAL ) {
		decalPoly_t* fade;

		fade = RE_AllocDecal( DECALPOLY_TYPE_FADE );

		memcpy( fade, &re_decalPolys[type][index], sizeof( decalPoly_t ) );

		fade->time = tr.refdef.time;
		fade->fadetime = tr.refdef.time + DECAL_FADE_TIME;
	}

	re_decalPolys[type][index].time = 0;

	re_decalPolyTotal[type]--;
}

/*
===================
RE_AllocDecal

Will allways succeed, even if it requires freeing an old active mark
===================
*/
decalPoly_t* RE_AllocDecal( int type ) {
	decalPoly_t	*le;

	// See if the cvar changed
	if ( re_decalPolyTotal[type] > r_markcount->integer )
		RE_ClearDecals();

	le = &re_decalPolys[type][re_decalPolyHead[type]];

	// If it has no time its the first occasion its been used
	if ( le->time ) {
		if ( le->time != tr.refdef.time ) {
			int i = re_decalPolyHead[type];

			// since we are killing one that existed before, make sure we
			// kill all the other marks that belong to the group
			do {
				i++;
				if ( i >= r_markcount->integer )
					i = 0;

				// Break out on the first one thats not part of the group
				if ( re_decalPolys[type][i].time != le->time )
					break;

				RE_FreeDecal ( type, i );
			} while ( i != re_decalPolyHead[type] );

			RE_FreeDecal( type, re_decalPolyHead[type] );
		}
		else
			RE_FreeDecal( type, re_decalPolyHead[type] );
	}

	memset( le, 0, sizeof(decalPoly_t) );
	le->time = tr.refdef.time;

	re_decalPolyTotal[type]++;

	// Move on to the next decal poly and wrap around if need be
	re_decalPolyHead[type]++;
	if ( re_decalPolyHead[type] >= r_markcount->integer )
		re_decalPolyHead[type] = 0;

	return le;
}

/*
=================
RE_AddDecalToScene

origin should be a point within a unit of the plane
dir should be the plane normal

temporary marks will not be stored or randomly oriented, but immediately
passed to the renderer.
=================
*/
#define	MAX_DECAL_FRAGMENTS	128
#define	MAX_DECAL_POINTS		384

void RE_AddDecalToScene( qhandle_t decalShader, const vec3_t origin, const vec3_t dir, float orientation, float red, float green, float blue, float alpha, qboolean alphaFade, float radius, qboolean temporary )
{
	matrix3_t		axis;
	float			texCoordScale;
	vec3_t			originalPoints[4];
	byte			colors[4];
	int				i, j;
	int				numFragments;
	markFragment_t	markFragments[MAX_DECAL_FRAGMENTS], *mf;
	vec3_t			markPoints[MAX_DECAL_POINTS];
	vec3_t			projection;

	assert(decalShader);

	if ( r_markcount->integer <= 0 && !temporary )
		return;

	if ( radius <= 0 )
		Com_Error( ERR_FATAL, "RE_AddDecalToScene:  called with <= 0 radius" );

	// create the texture axis
	VectorNormalize2( dir, axis[0] );
	PerpendicularVector( axis[1], axis[0] );
	RotatePointAroundVector( axis[2], axis[0], axis[1], orientation );
	CrossProduct( axis[0], axis[2], axis[1] );

	texCoordScale = 0.5 * 1.0 / radius;

	// create the full polygon
	for ( i = 0 ; i < 3 ; i++ )
	{
		originalPoints[0][i] = origin[i] - radius * axis[1][i] - radius * axis[2][i];
		originalPoints[1][i] = origin[i] + radius * axis[1][i] - radius * axis[2][i];
		originalPoints[2][i] = origin[i] + radius * axis[1][i] + radius * axis[2][i];
		originalPoints[3][i] = origin[i] - radius * axis[1][i] + radius * axis[2][i];
	}

	// get the fragments
	VectorScale( dir, -20, projection );
	numFragments = R_MarkFragments( 4, (const vec3_t*)originalPoints,
					projection, MAX_DECAL_POINTS, markPoints[0],
					MAX_DECAL_FRAGMENTS, markFragments );

	colors[0] = red * 255;
	colors[1] = green * 255;
	colors[2] = blue * 255;
	colors[3] = alpha * 255;

	for ( i = 0, mf = markFragments ; i < numFragments ; i++, mf++ )
	{
		polyVert_t	*v;
		polyVert_t	verts[MAX_VERTS_ON_DECAL_POLY];
		decalPoly_t	*decal;

		// we have an upper limit on the complexity of polygons
		// that we store persistantly
		if ( mf->numPoints > MAX_VERTS_ON_DECAL_POLY )
			mf->numPoints = MAX_VERTS_ON_DECAL_POLY;

		for ( j = 0, v = verts ; j < mf->numPoints ; j++, v++ )
		{
			vec3_t		delta;

			VectorCopy( markPoints[mf->firstPoint + j], v->xyz );

			VectorSubtract( v->xyz, origin, delta );
			v->st[0] = 0.5 + DotProduct( delta, axis[1] ) * texCoordScale;
			v->st[1] = 0.5 + DotProduct( delta, axis[2] ) * texCoordScale;

			for ( int k=0; k<4; k++ )
				v->modulate[k] = colors[k];
		}

		// if it is a temporary (shadow) mark, add it immediately and forget about it
		if ( temporary )
		{
			RE_AddPolyToScene( decalShader, mf->numPoints, verts, 1 );
			continue;
		}

		// otherwise save it persistantly
		decal = RE_AllocDecal( DECALPOLY_TYPE_NORMAL );
		decal->time = tr.refdef.time;
		decal->shader = decalShader;
		decal->poly.numVerts = mf->numPoints;
		decal->color[0] = red;
		decal->color[1] = green;
		decal->color[2] = blue;
		decal->color[3] = alpha;
		memcpy( decal->verts, verts, mf->numPoints * sizeof( verts[0] ) );
	}
}

/*
===============
R_AddDecals
===============
*/
void R_AddDecals( void )
{
	int			decalPoly;
	int			type;
	static int  lastMarkCount = -1;

	if ( r_markcount->integer != lastMarkCount ) {
		if ( lastMarkCount != -1 )
			RE_ClearDecals();

		lastMarkCount = r_markcount->integer;
	}

	if ( r_markcount->integer <= 0 )
		return;

	for ( type = DECALPOLY_TYPE_NORMAL; type < DECALPOLY_TYPE_MAX; type ++ )
	{
		decalPoly = re_decalPolyHead[type];

		do
		{
			decalPoly_t* p = &re_decalPolys[type][decalPoly];

			if ( p->time )
			{
				if ( p->fadetime )
				{
					int t;

					// fade all marks out with time
					t = tr.refdef.time - p->time;
					if ( t < DECAL_FADE_TIME )
					{
						float fade;
						int	  j;

						fade = 255.0f * (1.0f - ((float)t / DECAL_FADE_TIME));

						for ( j = 0 ; j < p->poly.numVerts ; j++ )
						{
							p->verts[j].modulate[3] = fade;
						}

						RE_AddPolyToScene( p->shader, p->poly.numVerts, p->verts, 1 );
					}
					else
					{
						RE_FreeDecal ( type, decalPoly );
					}
				}
				else
				{
					RE_AddPolyToScene( p->shader, p->poly.numVerts, p->verts, 1 );
				}
			}

			decalPoly++;
			if ( decalPoly >= r_markcount->integer )
			{
				decalPoly = 0;
			}
		}
		while ( decalPoly != re_decalPolyHead[type] );
	}
}