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

Doom 3 BFG Edition GPL Source Code
Copyright (C) 1993-2012 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 BFG Edition GPL Source Code ("Doom 3 BFG Edition Source Code").  

Doom 3 BFG Edition Source Code 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.

Doom 3 BFG Edition Source Code 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 Doom 3 BFG Edition Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 BFG Edition Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 BFG Edition Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

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

#include "PreLightShadowVolume_local.h"

/*
===================
PreLightShadowVolumeJob
===================
*/
void PreLightShadowVolumeJob( const preLightShadowVolumeParms_t * parms ) {
	if ( parms->tempCullBits == NULL ) {
		*const_cast< byte ** >( &parms->tempCullBits ) = (byte *)_alloca16( TEMP_CULLBITS( parms->numVerts ) );
	}

	// Calculate the shadow depth bounds.
	float shadowZMin = parms->lightZMin;
	float shadowZMax = parms->lightZMax;
	if ( parms->useShadowDepthBounds ) {
		// NOTE: pre-light shadow volumes typically cover the whole light volume so
		// there is no real point in trying to calculate tighter depth bounds here
		shadowZMin = Max( shadowZMin, parms->lightZMin );
		shadowZMax = Min( shadowZMax, parms->lightZMax );
	}

	bool renderZFail = false;
	int numShadowIndices = 0;

	// The shadow volume may be depth culled if either the shadow volume was culled to the view frustum or if the
	// depth range of the visible part of the shadow volume is outside the depth range of the light volume.
	if ( shadowZMin < shadowZMax ) {
		// Check if we need to render the shadow volume with Z-fail.
		// If the view is potentially inside the shadow volume bounds we may need to render with Z-fail.
		if ( parms->triangleBounds.Expand( parms->zNear * INSIDE_SHADOW_VOLUME_EXTRA_STRETCH ).ContainsPoint( parms->localViewOrigin ) ) {
			// Optionally perform a more precise test to see whether or not the view is inside the shadow volume.
			if ( parms->useShadowPreciseInsideTest && parms->verts != NULL && parms->indexes != NULL ) {
				renderZFail = R_ViewInsideShadowVolume( parms->tempCullBits, parms->verts, parms->numVerts, parms->indexes, parms->numIndexes,
														parms->localLightOrigin, parms->localViewOrigin, parms->zNear * INSIDE_SHADOW_VOLUME_EXTRA_STRETCH );
			} else {
				renderZFail = true;
			}
		}

		// must always draw the caps because pre-light shadows do not project to infinity
		numShadowIndices = parms->numIndexes;
	}

	// write out the number of shadow indices
	if ( parms->numShadowIndices != NULL ) {
		*parms->numShadowIndices = numShadowIndices;
	}
	// write out whether or not the shadow volume needs to be rendered with Z-Fail
	if ( parms->renderZFail != NULL ) {
		*parms->renderZFail = renderZFail;
	}
	// write out the shadow depth bounds
	if ( parms->shadowZMin != NULL ) {
		*parms->shadowZMin = shadowZMin;
	}
	if ( parms->shadowZMax != NULL ) {
		*parms->shadowZMax = shadowZMax;
	}
	// write out the shadow volume state
	if ( parms->shadowVolumeState != NULL ) {
		*parms->shadowVolumeState = SHADOWVOLUME_DONE;
	}
}

REGISTER_PARALLEL_JOB( PreLightShadowVolumeJob, "PreLightShadowVolumeJob" );
