// Copyright (C) 2001-2002 Raven Software.
//
// cg_localents.c -- every frame, generate renderer commands for locally
// processed entities, like smoke puffs, shells, etc.

#include "cg_local.h"

#define	MAX_LOCAL_ENTITIES	512
localEntity_t	cg_localEntities[MAX_LOCAL_ENTITIES];
localEntity_t	cg_activeLocalEntities;		// double linked list
localEntity_t	*cg_freeLocalEntities;		// single linked list

/*
===================
CG_InitLocalEntities

This is called at startup and for map restarts
===================
*/
void CG_InitLocalEntities( void ) 
{
	int		i;

	memset( cg_localEntities, 0, sizeof( cg_localEntities ) );
	cg_activeLocalEntities.next = &cg_activeLocalEntities;
	cg_activeLocalEntities.prev = &cg_activeLocalEntities;
	cg_freeLocalEntities = cg_localEntities;
	
	for ( i = 0 ; i < MAX_LOCAL_ENTITIES - 1 ; i++ ) 
	{
		cg_localEntities[i].next = &cg_localEntities[i+1];
	}
}


/*
==================
CG_FreeLocalEntity
==================
*/
void CG_FreeLocalEntity( localEntity_t *le ) 
{
	if ( !le->prev ) 
	{
		Com_Error( ERR_FATAL, "CG_FreeLocalEntity: not active" );
	}

	if (le->refEntity.ghoul2)
	{
		trap_G2API_CleanGhoul2Models(&le->refEntity.ghoul2);
	}

	// remove from the doubly linked active list
	le->prev->next = le->next;
	le->next->prev = le->prev;

	// the free list is only singly linked
	le->next = cg_freeLocalEntities;
	cg_freeLocalEntities = le;
}

/*
===================
CG_AllocLocalEntity

Will allways succeed, even if it requires freeing an old active entity
===================
*/
localEntity_t	*CG_AllocLocalEntity( void ) {
	localEntity_t	*le;

	if ( !cg_freeLocalEntities ) {
		// no free entities, so free the one at the end of the chain
		// remove the oldest active entity
		CG_FreeLocalEntity( cg_activeLocalEntities.prev );
	}

	le = cg_freeLocalEntities;
	cg_freeLocalEntities = cg_freeLocalEntities->next;

	memset( le, 0, sizeof( *le ) );

	// link into the active list
	le->next = cg_activeLocalEntities.next;
	le->prev = &cg_activeLocalEntities;
	cg_activeLocalEntities.next->prev = le;
	cg_activeLocalEntities.next = le;
	return le;
}


/*
====================================================================================

FRAGMENT PROCESSING

A fragment localentity interacts with the environment in some way (hitting walls),
or generates more localentities along a trail.

====================================================================================
*/


/*
================
CG_FragmentBounceMark
================
*/
void CG_FragmentBounceMark( localEntity_t *le, trace_t *trace ) {
	int			radius;

	if ( le->leMarkType == LEMT_BLOOD ) 
	{
		radius = 16 + (rand()&31);

		trap_R_AddDecalToScene ( cgs.media.bloodMarkShader, trace->endpos, 
								 trace->plane.normal, random()*360,
								 1,1,1,1, qtrue, radius, qfalse );

	} 
	else if ( le->leMarkType == LEMT_BURN ) 
	{
		radius = 8 + (rand()&15);

		trap_R_AddDecalToScene ( cgs.media.burnMarkShader, trace->endpos, 
								 trace->plane.normal, random()*360,
								 1,1,1,1, qtrue, radius, qfalse );
	}


	// don't allow a fragment to make multiple marks, or they
	// pile up while settling
	le->leMarkType = LEMT_NONE;
}

/*
================
CG_FragmentBounceSound
================
*/
void CG_FragmentBounceSound( localEntity_t *le, trace_t *trace ) 
{
	if ( le->leBounceSoundType == LEBS_BRASS ) 
	{
	}

	// don't allow a fragment to make multiple bounce sounds,
	// or it gets too noisy as they settle
	le->leBounceSoundType = LEBS_NONE;
}


/*
================
CG_ReflectVelocity
================
*/
void CG_ReflectVelocity( localEntity_t *le, trace_t *trace ) {
	vec3_t	velocity;
	float	dot;
	int		hitTime;

	// reflect the velocity on the trace plane
	hitTime = cg.time - cg.frametime + cg.frametime * trace->fraction;
	BG_EvaluateTrajectoryDelta( &le->pos, hitTime, velocity );
	dot = DotProduct( velocity, trace->plane.normal );
	VectorMA( velocity, -2*dot, trace->plane.normal, le->pos.trDelta );

	VectorScale( le->pos.trDelta, le->bounceFactor, le->pos.trDelta );

	VectorCopy( trace->endpos, le->pos.trBase );
	le->pos.trTime = cg.time;


	// check for stop, making sure that even on low FPS systems it doesn't bobble
	if ( trace->allsolid || 
		( trace->plane.normal[2] > 0 && 
		( le->pos.trDelta[2] < 40 || le->pos.trDelta[2] < -cg.frametime * le->pos.trDelta[2] ) ) ) {
		le->pos.trType = TR_STATIONARY;
	} else {

	}
}

/*
================
CG_AddFragment
================
*/
void CG_AddFragment( localEntity_t *le ) {
	vec3_t	newOrigin;
	trace_t	trace;

	if ( le->pos.trType == TR_STATIONARY ) {
		// sink into the ground if near the removal time
		int		t;
		float	oldZ;
		
		t = le->endTime - cg.time;
		if ( t < SINK_TIME ) {
			// we must use an explicit lighting origin, otherwise the
			// lighting would be lost as soon as the origin went
			// into the ground
			VectorCopy( le->refEntity.origin, le->refEntity.lightingOrigin );
			le->refEntity.renderfx |= RF_LIGHTING_ORIGIN;
			oldZ = le->refEntity.origin[2];
			le->refEntity.origin[2] -= 16 * ( 1.0 - (float)t / SINK_TIME );
			trap_R_AddRefEntityToScene( &le->refEntity );
			le->refEntity.origin[2] = oldZ;
		} else {
			trap_R_AddRefEntityToScene( &le->refEntity );
		}

		return;
	}

	// calculate new position
	BG_EvaluateTrajectory( &le->pos, cg.time, newOrigin );

	// trace a line from previous position to new position
	CG_Trace( &trace, le->refEntity.origin, NULL, NULL, newOrigin, -1, CONTENTS_SOLID );

	if ( trace.fraction == 1.0 ) {
		// still in free fall
		VectorCopy( newOrigin, le->refEntity.origin );

		if ( le->leFlags & LEF_TUMBLE ) {
			vec3_t angles;

			BG_EvaluateTrajectory( &le->angles, cg.time, angles );
			AnglesToAxis( angles, le->refEntity.axis );
		}

		trap_R_AddRefEntityToScene( &le->refEntity );
		return;
	}

	// if it is in a nodrop zone, remove it
	// this keeps gibs from waiting at the bottom of pits of death
	// and floating levels
	if ( trap_CM_PointContents( trace.endpos, 0 ) & CONTENTS_NODROP ) 
	{
		CG_FreeLocalEntity( le );
		return;
	}

	if (!trace.startsolid)
	{
		// leave a mark
		CG_FragmentBounceMark( le, &trace );

		// do a bouncy sound
		CG_FragmentBounceSound( le, &trace );

		// reflect the velocity on the trace plane
		CG_ReflectVelocity( le, &trace );

		trap_R_AddRefEntityToScene( &le->refEntity );
	}
}

/*
=====================================================================

TRIVIAL LOCAL ENTITIES

These only do simple scaling or modulation before passing to the renderer
=====================================================================
*/

/*
====================
CG_AddFadeRGB
====================
*/
void CG_AddFadeRGB( localEntity_t *le ) {
	refEntity_t *re;
	float c;

	re = &le->refEntity;

	c = ( le->endTime - cg.time ) * le->lifeRate;
	c *= 0xff;

	re->shaderRGBA[0] = le->color[0] * c;
	re->shaderRGBA[1] = le->color[1] * c;
	re->shaderRGBA[2] = le->color[2] * c;
	re->shaderRGBA[3] = le->color[3] * c;

	trap_R_AddRefEntityToScene( re );
}

/*
==================
CG_AddMoveScaleFade
==================
*/
static void CG_AddMoveScaleFade( localEntity_t *le ) {
	refEntity_t	*re;
	float		c;
	vec3_t		delta;
	float		len;

	re = &le->refEntity;

	if ( le->fadeInTime > le->startTime && cg.time < le->fadeInTime ) {
		// fade / grow time
		c = 1.0 - (float) ( le->fadeInTime - cg.time ) / ( le->fadeInTime - le->startTime );
	}
	else {
		// fade / grow time
		c = ( le->endTime - cg.time ) * le->lifeRate;
	}

	re->shaderRGBA[3] = 0xff * c * le->color[3];

	if ( !( le->leFlags & LEF_PUFF_DONT_SCALE ) ) {
		re->radius = le->radius * ( 1.0 - c ) + 8;
	}

	BG_EvaluateTrajectory( &le->pos, cg.time, re->origin );

	// if the view would be "inside" the sprite, kill the sprite
	// so it doesn't add too much overdraw
	VectorSubtract( re->origin, cg.refdef.vieworg, delta );
	len = VectorLength( delta );
	if ( len < le->radius ) {
		CG_FreeLocalEntity( le );
		return;
	}

	trap_R_AddRefEntityToScene( re );
}

/*
===================
CG_AddScaleFade

For rocket smokes that hang in place, fade out, and are
removed if the view passes through them.
There are often many of these, so it needs to be simple.
===================
*/
static void CG_AddScaleFade( localEntity_t *le ) {
	refEntity_t	*re;
	float		c;
	vec3_t		delta;
	float		len;

	re = &le->refEntity;

	// fade / grow time
	c = ( le->endTime - cg.time ) * le->lifeRate;

	re->shaderRGBA[3] = 0xff * c * le->color[3];
	re->radius = le->radius * ( 1.0 - c ) + 8;

	// if the view would be "inside" the sprite, kill the sprite
	// so it doesn't add too much overdraw
	VectorSubtract( re->origin, cg.refdef.vieworg, delta );
	len = VectorLength( delta );
	if ( len < le->radius ) {
		CG_FreeLocalEntity( le );
		return;
	}

	trap_R_AddRefEntityToScene( re );
}


/*
=================
CG_AddFallScaleFade

This is just an optimized CG_AddMoveScaleFade
For blood mists that drift down, fade out, and are
removed if the view passes through them.
There are often 100+ of these, so it needs to be simple.
=================
*/
static void CG_AddFallScaleFade( localEntity_t *le ) {
	refEntity_t	*re;
	float		c;
	vec3_t		delta;
	float		len;

	re = &le->refEntity;

	// fade time
	c = ( le->endTime - cg.time ) * le->lifeRate;

	re->shaderRGBA[3] = 0xff * c * le->color[3];

	re->origin[2] = le->pos.trBase[2] - ( 1.0 - c ) * le->pos.trDelta[2];

	re->radius = le->radius * ( 1.0 - c ) + 16;

	// if the view would be "inside" the sprite, kill the sprite
	// so it doesn't add too much overdraw
	VectorSubtract( re->origin, cg.refdef.vieworg, delta );
	len = VectorLength( delta );
	if ( len < le->radius ) {
		CG_FreeLocalEntity( le );
		return;
	}

	trap_R_AddRefEntityToScene( re );
}

/*
===================
CG_AddRefEntity
===================
*/
void CG_AddRefEntity( localEntity_t *le ) 
{
	if (le->endTime < cg.time) 
	{
		CG_FreeLocalEntity( le );
		return;
	}
	trap_R_AddRefEntityToScene( &le->refEntity );
}


/*
===================
CG_AddLine
===================
*/
void CG_AddLine( localEntity_t *le )
{
	refEntity_t	*re;

	re = &le->refEntity;

	re->reType = RT_LINE;

	trap_R_AddRefEntityToScene( re );
}

/*
================
CG_AddGib
================
*/
void CG_AddGib( localEntity_t *le ) {
	vec3_t	newOrigin;
	trace_t	trace;

	if ( le->pos.trType == TR_STATIONARY ) {
		// sink into the ground if near the removal time
		int		t;
		float	oldZ;
		
		le->refEntity.origin[2] += le->zOffset;
		t = le->endTime - cg.time;
		if ( t < SINK_TIME ) {
			// we must use an explicit lighting origin, otherwise the
			// lighting would be lost as soon as the origin went
			// into the ground
			VectorCopy( le->refEntity.origin, le->refEntity.lightingOrigin );
			le->refEntity.renderfx |= RF_LIGHTING_ORIGIN;
			oldZ = le->refEntity.origin[2];
			le->refEntity.origin[2] -= 16 * ( 1.0 - (float)t / SINK_TIME );
			trap_R_AddRefEntityToScene( &le->refEntity );
			le->refEntity.origin[2] = oldZ;
		} else {
			trap_R_AddRefEntityToScene( &le->refEntity );
		}
		le->refEntity.origin[2] -= le->zOffset;

		return;
	}

	// calculate new position
	BG_EvaluateTrajectory( &le->pos, cg.time, newOrigin );

	// trace a line from previous position to new position
	CG_Trace( &trace, le->refEntity.origin, NULL, NULL, newOrigin, -1, CONTENTS_SOLID );
	if ( trace.fraction == 1.0 ) {
		// still in free fall
		VectorCopy( newOrigin, le->refEntity.origin );

		if ( le->leFlags & LEF_TUMBLE ) {
			vec3_t angles;

			BG_EvaluateTrajectory( &le->angles, cg.time, angles );
			AnglesToAxis( angles, le->refEntity.axis );
		}

		le->refEntity.origin[2] += le->zOffset;
		trap_R_AddRefEntityToScene( &le->refEntity );
		le->refEntity.origin[2] -= le->zOffset;

		return;
	}

	// if it is in a nodrop zone, remove it
	// this keeps gibs from waiting at the bottom of pits of death
	// and floating levels
	if ( trap_CM_PointContents( trace.endpos, 0 ) & CONTENTS_NODROP ) 
	{
		CG_FreeLocalEntity( le );
		return;
	}

	if (!trace.startsolid)
	{
		// leave a mark
//		CG_FragmentBounceMark( le, &trace );

		// do a bouncy sound
//		CG_FragmentBounceSound( le, &trace );

		// reflect the velocity on the trace plane
		CG_ReflectVelocity( le, &trace );

		le->refEntity.origin[2] += le->zOffset;
		trap_R_AddRefEntityToScene( &le->refEntity );
		le->refEntity.origin[2] -= le->zOffset;
	}
}

//==============================================================================

/*
===================
CG_AddLocalEntities
===================
*/
void CG_AddLocalEntities( void ) 
{
	localEntity_t	*le, *next;

	// walk the list backwards, so any new local entities generated
	// (trails, marks, etc) will be present this frame
	le = cg_activeLocalEntities.prev;
	for ( ; le != &cg_activeLocalEntities ; le = next ) 
	{
		// grab next now, so if the local entity is freed we
		// still have it
		next = le->prev;

		if ( cg.time >= le->endTime ) 
		{
			CG_FreeLocalEntity( le );
			continue;
		}

		switch ( le->leType ) 
		{
			default:
				Com_Error( ERR_FATAL, "Bad leType: %i", le->leType );
				break;

			case LE_FRAGMENT:
				CG_AddFragment( le );
				break;

			case LE_MOVE_SCALE_FADE:
				CG_AddMoveScaleFade( le );
				break;

			case LE_FADE_RGB:
				CG_AddFadeRGB( le );
				break;

			case LE_FALL_SCALE_FADE:
				CG_AddFallScaleFade( le );
				break;

			case LE_SCALE_FADE:
				CG_AddScaleFade( le );
				break;

			case LE_SHOWREFENTITY:
				CG_AddRefEntity( le );
				break;

			case LE_LINE:
				CG_AddLine( le );
				break;

			case LE_GIB:
				CG_AddGib(le);
				break;
		}
	}
}