/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena 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 2 of the License,
or (at your option) any later version.

Quake III Arena 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 Quake III Arena source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
// tr_mesh.c: triangle model functions

#include "tr_local.h"


static float ProjectRadius( float r, const vec3_t location )
{
	float pr;
	float dist;
	float c;
	vec3_t	p;
	float	projected[4];

	c = DotProduct( tr.viewParms.orient.axis[0], tr.viewParms.orient.origin );
	dist = DotProduct( tr.viewParms.orient.axis[0], location ) - c;

	if ( dist <= 0 )
		return 0;

	p[0] = 0;
	p[1] = fabs( r );
	p[2] = -dist;

	projected[0] = p[0] * tr.viewParms.projectionMatrix[0] + 
		           p[1] * tr.viewParms.projectionMatrix[4] +
				   p[2] * tr.viewParms.projectionMatrix[8] +
				   tr.viewParms.projectionMatrix[12];

	projected[1] = p[0] * tr.viewParms.projectionMatrix[1] + 
		           p[1] * tr.viewParms.projectionMatrix[5] +
				   p[2] * tr.viewParms.projectionMatrix[9] +
				   tr.viewParms.projectionMatrix[13];

	projected[2] = p[0] * tr.viewParms.projectionMatrix[2] + 
		           p[1] * tr.viewParms.projectionMatrix[6] +
				   p[2] * tr.viewParms.projectionMatrix[10] +
				   tr.viewParms.projectionMatrix[14];

	projected[3] = p[0] * tr.viewParms.projectionMatrix[3] + 
		           p[1] * tr.viewParms.projectionMatrix[7] +
				   p[2] * tr.viewParms.projectionMatrix[11] +
				   tr.viewParms.projectionMatrix[15];


	pr = projected[1] / projected[3];

	if ( pr > 1.0f )
		pr = 1.0f;

	return pr;
}


static int R_CullModel( const md3Header_t* header, trRefEntity_t* ent )
{
	const md3Frame_t	*oldFrame, *newFrame;

	// compute frame pointers
	newFrame = (const md3Frame_t*) ( ( byte * ) header + header->ofsFrames ) + ent->e.frame;
	oldFrame = (const md3Frame_t*) ( ( byte * ) header + header->ofsFrames ) + ent->e.oldframe;

	// cull bounding sphere ONLY if this is not an upscaled entity
	if ( !ent->e.nonNormalizedAxes )
	{
		if ( ent->e.frame == ent->e.oldframe )
		{
			switch ( R_CullLocalPointAndRadius( newFrame->localOrigin, newFrame->radius ) )
			{
			case CULL_OUT:
				tr.pc[RF_MD3_CULL_S_OUT]++;
				return CULL_OUT;

			case CULL_IN:
				tr.pc[RF_MD3_CULL_S_IN]++;
				return CULL_IN;

			case CULL_CLIP:
				tr.pc[RF_MD3_CULL_S_CLIP]++;
				break;
			}
		}
		else
		{
			int sphereCull, sphereCullB;

			sphereCull  = R_CullLocalPointAndRadius( newFrame->localOrigin, newFrame->radius );
			if ( newFrame == oldFrame ) {
				sphereCullB = sphereCull;
			} else {
				sphereCullB = R_CullLocalPointAndRadius( oldFrame->localOrigin, oldFrame->radius );
			}

			if ( sphereCull == sphereCullB )
			{
				if ( sphereCull == CULL_OUT )
				{
					tr.pc[RF_MD3_CULL_S_OUT]++;
					return CULL_OUT;
				}
				else if ( sphereCull == CULL_IN )
				{
					tr.pc[RF_MD3_CULL_S_IN]++;
					return CULL_IN;
				}
				else
				{
					tr.pc[RF_MD3_CULL_S_CLIP]++;
				}
			}
		}
	}
	
	// calculate a bounding box in the current coordinate system
	vec3_t bounds[2];
	for (int i = 0; i < 3; ++i) {
		bounds[0][i] = min( oldFrame->bounds[0][i], newFrame->bounds[0][i] );
		bounds[1][i] = max( oldFrame->bounds[1][i], newFrame->bounds[1][i] );
	}

	switch ( R_CullLocalBox( bounds ) )
	{
	case CULL_IN:
		tr.pc[RF_MD3_CULL_B_IN]++;
		return CULL_IN;
	case CULL_CLIP:
		tr.pc[RF_MD3_CULL_B_CLIP]++;
		return CULL_CLIP;
	case CULL_OUT:
	default:
		tr.pc[RF_MD3_CULL_B_OUT]++;
		return CULL_OUT;
	}
}


static int R_ComputeLOD( const trRefEntity_t* ent )
{
	float radius;
	float flod;
	float projectedRadius;
	int lod;

	if ( tr.currentModel->numLods < 2 )
	{
		// model has only 1 LOD level, skip computations and bias
		lod = 0;
	}
	else
	{
		// multiple LODs exist, so compute projected bounding sphere
		// and use that as a criteria for selecting LOD
		const md3Frame_t* frame = (const md3Frame_t*)(((unsigned char *)tr.currentModel->md3[0]) + tr.currentModel->md3[0]->ofsFrames);
		frame += ent->e.frame;
		radius = RadiusFromBounds( frame->bounds[0], frame->bounds[1] );

		if ( ( projectedRadius = ProjectRadius( radius, ent->e.origin ) ) != 0 )
		{
			flod = 1.0f - projectedRadius * r_lodscale->value;
		}
		else
		{
			// object intersects near view plane, e.g. view weapon
			flod = 0;
		}

		flod *= tr.currentModel->numLods;
		lod = (int)flod;

		if ( lod < 0 )
		{
			lod = 0;
		}
		else if ( lod >= tr.currentModel->numLods )
		{
			lod = tr.currentModel->numLods - 1;
		}
	}

	lod += r_lodbias->integer;
	
	if ( lod >= tr.currentModel->numLods )
		lod = tr.currentModel->numLods - 1;
	if ( lod < 0 )
		lod = 0;

	return lod;
}


void R_AddMD3Surfaces( trRefEntity_t* ent )
{
	// don't add third_person objects if not in a portal
	qbool personalModel = (ent->e.renderfx & RF_THIRD_PERSON) != 0 && !tr.viewParms.isPortal;

	if ( ent->e.renderfx & RF_WRAP_FRAMES ) {
		ent->e.frame %= tr.currentModel->md3[0]->numFrames;
		ent->e.oldframe %= tr.currentModel->md3[0]->numFrames;
	}

	//
	// Validate the frames so there is no chance of a crash.
	// This will write directly into the entity structure, so
	// when the surfaces are rendered, they don't need to be
	// range checked again.
	//
	if ( (ent->e.frame >= tr.currentModel->md3[0]->numFrames) 
		|| (ent->e.frame < 0)
		|| (ent->e.oldframe >= tr.currentModel->md3[0]->numFrames)
		|| (ent->e.oldframe < 0) ) {
			ri.Printf( PRINT_DEVELOPER, "R_AddMD3Surfaces: no such frame %d to %d for '%s'\n",
				ent->e.oldframe, ent->e.frame,
				tr.currentModel->name );
			ent->e.frame = 0;
			ent->e.oldframe = 0;
	}

	int lod = R_ComputeLOD( ent );
	const md3Header_t* header = tr.currentModel->md3[lod];

	// cull the entire model if merged bounding box of both frames is outside the view frustum
	if (R_CullModel(header, ent) == CULL_OUT)
		return;

	// set up lighting now that we know we aren't culled
	if (!personalModel)
		R_SetupEntityLighting( &tr.refdef, ent );

	// draw all surfaces
	const shader_t* shader;
	const md3Surface_t* surface = (const md3Surface_t*)((byte *)header + header->ofsSurfaces);

	for (int i = 0; i < header->numSurfaces; ++i) {
		if ( ent->e.customShader ) {
			shader = R_GetShaderByHandle( ent->e.customShader );
		} else if ( ent->e.customSkin > 0 && ent->e.customSkin < tr.numSkins ) {
			// match the surface name to something in the skin file
			const skin_t* skin = R_GetSkinByHandle(ent->e.customSkin);

			shader = tr.defaultShader;
			for (int j = 0; j < skin->numSurfaces; ++j) {
				// the names have both been lowercased
				if ( !strcmp( skin->surfaces[j]->name, surface->name ) ) {
					shader = skin->surfaces[j]->shader;
					break;
				}
			}
			if (shader == tr.defaultShader) {
				ri.Printf( PRINT_DEVELOPER, "WARNING: no shader for surface %s in skin %s\n", surface->name, skin->name);
			}
			else if (shader->defaultShader) {
				ri.Printf( PRINT_DEVELOPER, "WARNING: shader %s in skin %s not found\n", shader->name, skin->name);
			}
		} else if ( surface->numShaders <= 0 ) {
			shader = tr.defaultShader;
		} else {
			const md3Shader_t* md3Shader = (const md3Shader_t*)((byte *)surface + surface->ofsShaders);
			md3Shader += ent->e.skinNum % surface->numShaders;
			shader = tr.shaders[ md3Shader->shaderIndex ];
		}

		// don't add third_person objects if not viewing through a portal
		if ( !personalModel ) {
			R_AddDrawSurf( (const surfaceType_t*)surface, shader );
		}

		surface = (const md3Surface_t*)( (byte *)surface + surface->ofsEnd );
	}

}