/*
cl_part.c - particles and tracers
Copyright (C) 2010 Uncle Mike

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 3 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.
*/

#include "gl_local.h"
#include "r_efx.h"
#include "event_flags.h"
#include "entity_types.h"
#include "triangleapi.h"
#include "pm_local.h"
#include "cl_tent.h"
#include "studio.h"

/*
================
CL_DrawParticles

update particle color, position, free expired and draw it
================
*/
void CL_DrawParticles( double frametime, particle_t *cl_active_particles )
{
	particle_t	*p;
	float		time3 = 15.0f * frametime;
	float		time2 = 10.0f * frametime;
	float		time1 = 5.0f * frametime;
	float		dvel = 4.0f * frametime;
	float		grav = frametime * MOVEVARS->gravity * 0.05f;
	vec3_t		right, up;
	color24		*pColor;
	int		alpha;
	float		size;

	if( !cl_draw_particles->value )
		return;

	if( !cl_active_particles )
		return;	// nothing to draw?

	pglEnable( GL_BLEND );
	pglDisable( GL_ALPHA_TEST );
	pglBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );

	GL_Bind( XASH_TEXTURE0, tr.particleTexture );
	pglTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
	pglDepthMask( GL_FALSE );

	pglBegin( GL_QUADS );

	for( p = cl_active_particles; p; p = p->next )
	{
		if(( p->type != pt_blob ) || ( p->packedColor == 255 ))
		{
			size = PART_SIZE; // get initial size of particle

			// scale up to keep particles from disappearing
			size += (p->org[0] - RI.vieworg[0]) * RI.cull_vforward[0];
			size += (p->org[1] - RI.vieworg[1]) * RI.cull_vforward[1];
			size += (p->org[2] - RI.vieworg[2]) * RI.cull_vforward[2];

			if( size < 20.0f ) size = PART_SIZE;
			else size = PART_SIZE + size * 0.002f;

			// scale the axes by radius
			VectorScale( RI.cull_vright, size, right );
			VectorScale( RI.cull_vup, size, up );

			p->color = bound( 0, p->color, 255 );
			pColor = &clgame.palette[p->color];

			alpha = 255 * (p->die - gpGlobals->time) * 16.0f;
			if( alpha > 255 || p->type == pt_static )
				alpha = 255;

			pglColor4ub( LightToTexGamma( pColor->r ), LightToTexGamma( pColor->g ), LightToTexGamma( pColor->b ), alpha );

			pglTexCoord2f( 0.0f, 1.0f );
			pglVertex3f( p->org[0] - right[0] + up[0], p->org[1] - right[1] + up[1], p->org[2] - right[2] + up[2] );
			pglTexCoord2f( 0.0f, 0.0f );
			pglVertex3f( p->org[0] + right[0] + up[0], p->org[1] + right[1] + up[1], p->org[2] + right[2] + up[2] );
			pglTexCoord2f( 1.0f, 0.0f );
			pglVertex3f( p->org[0] + right[0] - up[0], p->org[1] + right[1] - up[1], p->org[2] + right[2] - up[2] );
			pglTexCoord2f( 1.0f, 1.0f );
			pglVertex3f( p->org[0] - right[0] - up[0], p->org[1] - right[1] - up[1], p->org[2] - right[2] - up[2] );
			r_stats.c_particle_count++;
		}

		if( p->type != pt_clientcustom )
		{
			// update position.
			VectorMA( p->org, frametime, p->vel, p->org );
		}

		switch( p->type )
		{
		case pt_static:
			break;
		case pt_fire:
			p->ramp += time1;
			if( p->ramp >= 6.0f ) p->die = -1.0f;
			else p->color = ramp3[(int)p->ramp];
			p->vel[2] += grav;
			break;
		case pt_explode:
			p->ramp += time2;
			if( p->ramp >= 8.0f ) p->die = -1.0f;
			else p->color = ramp1[(int)p->ramp];
			VectorMA( p->vel, dvel, p->vel, p->vel );
			p->vel[2] -= grav;
			break;
		case pt_explode2:
			p->ramp += time3;
			if( p->ramp >= 8.0f ) p->die = -1.0f;
			else p->color = ramp2[(int)p->ramp];
			VectorMA( p->vel,-frametime, p->vel, p->vel );
			p->vel[2] -= grav;
			break;
		case pt_blob:
			if( p->packedColor == 255 )
			{
				// normal blob explosion
				VectorMA( p->vel, dvel, p->vel, p->vel );
				p->vel[2] -= grav;
				break;
			}
		case pt_blob2:
			if( p->packedColor == 255 )
			{
				// normal blob explosion
				p->vel[0] -= p->vel[0] * dvel;
				p->vel[1] -= p->vel[1] * dvel;
				p->vel[2] -= grav;
			}
			else
			{
				p->ramp += time2;
				if( p->ramp >= 9.0f ) p->ramp = 0.0f;
				p->color = gSparkRamp[(int)p->ramp];
				VectorMA( p->vel, -frametime * 0.5f, p->vel, p->vel );
				p->type = COM_RandomLong( 0, 3 ) ? pt_blob : pt_blob2;
				p->vel[2] -= grav * 5.0f;
			}
			break;
		case pt_grav:
			p->vel[2] -= grav * 20.0f;
			break;
		case pt_slowgrav:
			p->vel[2] -= grav;
			break;
		case pt_vox_grav:
			p->vel[2] -= grav * 8.0f;
			break;
		case pt_vox_slowgrav:
			p->vel[2] -= grav * 4.0f;
			break;
		case pt_clientcustom:
			if( p->callback )
				p->callback( p, frametime );
			break;
		}
	}

	pglEnd();
	pglDepthMask( GL_TRUE );
}

/*
================
CL_CullTracer

check tracer bbox
================
*/
static qboolean CL_CullTracer( particle_t *p, const vec3_t start, const vec3_t end )
{
	vec3_t	mins, maxs;
	int	i;

	// compute the bounding box
	for( i = 0; i < 3; i++ )
	{
		if( start[i] < end[i] )
		{
			mins[i] = start[i];
			maxs[i] = end[i];
		}
		else
		{
			mins[i] = end[i];
			maxs[i] = start[i];
		}
		
		// don't let it be zero sized
		if( mins[i] == maxs[i] )
		{
			maxs[i] += gTracerSize[p->type] * 2.0f;
		}
	}

	// check bbox
	return R_CullBox( mins, maxs );
}

/*
================
CL_DrawTracers

update tracer color, position, free expired and draw it
================
*/
void CL_DrawTracers( double frametime, particle_t *cl_active_tracers )
{
	float		scale, atten, gravity;
	vec3_t		screenLast, screen;
	vec3_t		start, end, delta;
	particle_t	*p;

	if( !cl_draw_tracers->value )
		return;

	// update tracer color if this is changed
	if( FBitSet( tracerred->flags|tracergreen->flags|tracerblue->flags|traceralpha->flags, FCVAR_CHANGED ))
	{
		gTracerColors[4].r = (byte)(tracerred->value * traceralpha->value * 255);
		gTracerColors[4].g = (byte)(tracergreen->value * traceralpha->value * 255);
		gTracerColors[4].b = (byte)(tracerblue->value * traceralpha->value * 255);
		ClearBits( tracerred->flags, FCVAR_CHANGED );
		ClearBits( tracergreen->flags, FCVAR_CHANGED );
		ClearBits( tracerblue->flags, FCVAR_CHANGED );
		ClearBits( traceralpha->flags, FCVAR_CHANGED );
	}

	if( !cl_active_tracers )
		return;	// nothing to draw?

	if( !TriSpriteTexture( cl_sprite_dot, 0 ))
		return;

	pglEnable( GL_BLEND );
	pglBlendFunc( GL_SRC_ALPHA, GL_ONE );
	pglDisable( GL_ALPHA_TEST );
	pglDepthMask( GL_FALSE );

	gravity = frametime * MOVEVARS->gravity;
	scale = 1.0 - (frametime * 0.9);
	if( scale < 0.0f ) scale = 0.0f;

	for( p = cl_active_tracers; p; p = p->next )
	{
		atten = (p->die - gpGlobals->time);
		if( atten > 0.1f ) atten = 0.1f;

		VectorScale( p->vel, ( p->ramp * atten ), delta );
		VectorAdd( p->org, delta, end );
		VectorCopy( p->org, start );

		if( !CL_CullTracer( p, start, end ))
		{
			vec3_t	verts[4], tmp2;
			vec3_t	tmp, normal;
			color24	*pColor;

			// Transform point into screen space
			TriWorldToScreen( start, screen );
			TriWorldToScreen( end, screenLast );

			// build world-space normal to screen-space direction vector
			VectorSubtract( screen, screenLast, tmp );

			// we don't need Z, we're in screen space
			tmp[2] = 0;
			VectorNormalize( tmp );

			// build point along noraml line (normal is -y, x)
			VectorScale( RI.cull_vup, tmp[0] * gTracerSize[p->type], normal );
			VectorScale( RI.cull_vright, -tmp[1] * gTracerSize[p->type], tmp2 );
			VectorSubtract( normal, tmp2, normal );

			// compute four vertexes
			VectorSubtract( start, normal, verts[0] ); 
			VectorAdd( start, normal, verts[1] ); 
			VectorAdd( verts[0], delta, verts[2] ); 
			VectorAdd( verts[1], delta, verts[3] ); 

			pColor = &gTracerColors[p->color];
			pglColor4ub( pColor->r, pColor->g, pColor->b, p->packedColor );

			pglBegin( GL_QUADS );
				pglTexCoord2f( 0.0f, 0.8f );
				pglVertex3fv( verts[2] );
				pglTexCoord2f( 1.0f, 0.8f );
				pglVertex3fv( verts[3] );
				pglTexCoord2f( 1.0f, 0.0f );
				pglVertex3fv( verts[1] );
				pglTexCoord2f( 0.0f, 0.0f );
				pglVertex3fv( verts[0] );
			pglEnd();
		}

		// evaluate position
		VectorMA( p->org, frametime, p->vel, p->org );

		if( p->type == pt_grav )
		{
			p->vel[0] *= scale;
			p->vel[1] *= scale;
			p->vel[2] -= gravity;

			p->packedColor = 255 * (p->die - gpGlobals->time) * 2;
			if( p->packedColor > 255 ) p->packedColor = 255;
		}
		else if( p->type == pt_slowgrav )
		{
			p->vel[2] = gravity * 0.05;
		}
	}

	pglDepthMask( GL_TRUE );
}

/*
===============
CL_DrawParticlesExternal

allow to draw effects from custom renderer
===============
*/
void CL_DrawParticlesExternal( const ref_viewpass_t *rvp, qboolean trans_pass, float frametime )
{
	ref_instance_t	oldRI = RI;

	memcpy( &oldRI, &RI, sizeof( ref_instance_t ));
	R_SetupRefParams( rvp );
	R_SetupFrustum();
	R_SetupGL( false );	// don't touch GL-states

	// setup PVS for frame
	memcpy( RI.visbytes, tr.visbytes, gpGlobals->visbytes );
	tr.frametime = frametime;

	CL_DrawEFX( frametime, trans_pass );

	// restore internal state
	memcpy( &RI, &oldRI, sizeof( ref_instance_t ));
}