/*
===========================================================================
Copyright (C) 2011 Thilo Schulz <thilo@tjps.eu>
Copyright (C) 2011 Matthias Bentrup <matthias.bentrup@googlemail.com>
Copyright (C) 2000-2013 Darklegion Development
Copyright (C) 2015-2019 GrangerHub

This file is part of Tremulous.

Tremulous 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.

Tremulous 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 Tremulous; if not, see <https://www.gnu.org/licenses/>

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

#include "tr_local.h"

#define	LL(x) x=LittleLong(x)

// 3x4 identity matrix
static float identityMatrix[12] = {
	1, 0, 0, 0,
	0, 1, 0, 0,
	0, 0, 1, 0
};

static bool IQM_CheckRange( iqmHeader_t *header, int offset,
				int count,int size ) {
	// return true if the range specified by offset, count and size
	// doesn't fit into the file
	return ( count <= 0 ||
		 offset < 0 ||
		 offset > header->filesize ||
		 offset + count * size < 0 ||
		 offset + count * size > header->filesize );
}
// "multiply" 3x4 matrices, these are assumed to be the top 3 rows
// of a 4x4 matrix with the last row = (0 0 0 1)
static void Matrix34Multiply( float *a, float *b, float *out ) {
	out[ 0] = a[0] * b[0] + a[1] * b[4] + a[ 2] * b[ 8];
	out[ 1] = a[0] * b[1] + a[1] * b[5] + a[ 2] * b[ 9];
	out[ 2] = a[0] * b[2] + a[1] * b[6] + a[ 2] * b[10];
	out[ 3] = a[0] * b[3] + a[1] * b[7] + a[ 2] * b[11] + a[ 3];
	out[ 4] = a[4] * b[0] + a[5] * b[4] + a[ 6] * b[ 8];
	out[ 5] = a[4] * b[1] + a[5] * b[5] + a[ 6] * b[ 9];
	out[ 6] = a[4] * b[2] + a[5] * b[6] + a[ 6] * b[10];
	out[ 7] = a[4] * b[3] + a[5] * b[7] + a[ 6] * b[11] + a[ 7];
	out[ 8] = a[8] * b[0] + a[9] * b[4] + a[10] * b[ 8];
	out[ 9] = a[8] * b[1] + a[9] * b[5] + a[10] * b[ 9];
	out[10] = a[8] * b[2] + a[9] * b[6] + a[10] * b[10];
	out[11] = a[8] * b[3] + a[9] * b[7] + a[10] * b[11] + a[11];
}
static void Matrix34Multiply_OnlySetOrigin( float *a, float *b, float *out ) {
	out[ 3] = a[0] * b[3] + a[1] * b[7] + a[ 2] * b[11] + a[ 3];
	out[ 7] = a[4] * b[3] + a[5] * b[7] + a[ 6] * b[11] + a[ 7];
	out[11] = a[8] * b[3] + a[9] * b[7] + a[10] * b[11] + a[11];
}
static void InterpolateMatrix( float *a, float *b, float lerp, float *mat ) {
	float unLerp = 1.0f - lerp;

	mat[ 0] = a[ 0] * unLerp + b[ 0] * lerp;
	mat[ 1] = a[ 1] * unLerp + b[ 1] * lerp;
	mat[ 2] = a[ 2] * unLerp + b[ 2] * lerp;
	mat[ 3] = a[ 3] * unLerp + b[ 3] * lerp;
	mat[ 4] = a[ 4] * unLerp + b[ 4] * lerp;
	mat[ 5] = a[ 5] * unLerp + b[ 5] * lerp;
	mat[ 6] = a[ 6] * unLerp + b[ 6] * lerp;
	mat[ 7] = a[ 7] * unLerp + b[ 7] * lerp;
	mat[ 8] = a[ 8] * unLerp + b[ 8] * lerp;
	mat[ 9] = a[ 9] * unLerp + b[ 9] * lerp;
	mat[10] = a[10] * unLerp + b[10] * lerp;
	mat[11] = a[11] * unLerp + b[11] * lerp;
}
static void JointToMatrix( vec4_t rot, vec3_t scale, vec3_t trans,
			   float *mat ) {
	float xx = 2.0f * rot[0] * rot[0];
	float yy = 2.0f * rot[1] * rot[1];
	float zz = 2.0f * rot[2] * rot[2];
	float xy = 2.0f * rot[0] * rot[1];
	float xz = 2.0f * rot[0] * rot[2];
	float yz = 2.0f * rot[1] * rot[2];
	float wx = 2.0f * rot[3] * rot[0];
	float wy = 2.0f * rot[3] * rot[1];
	float wz = 2.0f * rot[3] * rot[2];

	mat[ 0] = scale[0] * (1.0f - (yy + zz));
	mat[ 1] = scale[0] * (xy - wz);
	mat[ 2] = scale[0] * (xz + wy);
	mat[ 3] = trans[0];
	mat[ 4] = scale[1] * (xy + wz);
	mat[ 5] = scale[1] * (1.0f - (xx + zz));
	mat[ 6] = scale[1] * (yz - wx);
	mat[ 7] = trans[1];
	mat[ 8] = scale[2] * (xz - wy);
	mat[ 9] = scale[2] * (yz + wx);
	mat[10] = scale[2] * (1.0f - (xx + yy));
	mat[11] = trans[2];
}
static void Matrix34Invert( float *inMat, float *outMat )
{
	vec3_t trans;
	float invSqrLen, *v;

	outMat[ 0] = inMat[ 0]; outMat[ 1] = inMat[ 4]; outMat[ 2] = inMat[ 8];
	outMat[ 4] = inMat[ 1]; outMat[ 5] = inMat[ 5]; outMat[ 6] = inMat[ 9];
	outMat[ 8] = inMat[ 2]; outMat[ 9] = inMat[ 6]; outMat[10] = inMat[10];

	v = outMat + 0; invSqrLen = 1.0f / DotProduct(v, v); VectorScale(v, invSqrLen, v);
	v = outMat + 4; invSqrLen = 1.0f / DotProduct(v, v); VectorScale(v, invSqrLen, v);
	v = outMat + 8; invSqrLen = 1.0f / DotProduct(v, v); VectorScale(v, invSqrLen, v);

	trans[0] = inMat[ 3];
	trans[1] = inMat[ 7];
	trans[2] = inMat[11];

	outMat[ 3] = -DotProduct(outMat + 0, trans);
	outMat[ 7] = -DotProduct(outMat + 4, trans);
	outMat[11] = -DotProduct(outMat + 8, trans);
}

/*
=================
R_LoadIQM

Load an IQM model and compute the joint matrices for every frame.
=================
*/
bool R_LoadIQM( model_t *mod, void *buffer, int filesize, const char *mod_name ) {
	iqmHeader_t		*header;
	iqmVertexArray_t	*vertexarray;
	iqmTriangle_t		*triangle;
	iqmMesh_t		*mesh;
	iqmJoint_t		*joint;
	iqmPose_t		*pose;
	iqmBounds_t		*bounds;
	unsigned short		*framedata;
	char			*str;
	int			i, j;
	float			jointInvMats[IQM_MAX_JOINTS * 12] = {0.0f};
	float			*mat, *matInv;
	size_t			size, joint_names;
	iqmData_t		*iqmData;
	srfIQModel_t		*surface;
	char			meshName[MAX_QPATH];
	byte			blendIndexesType, blendWeightsType;

	if( filesize < sizeof(iqmHeader_t) ) {
		return false;
	}

	header = (iqmHeader_t *)buffer;
	if( Q_strncmp( header->magic, IQM_MAGIC, sizeof(header->magic) ) ) {
		return false;
	}

	LL( header->version );
	if( header->version != IQM_VERSION ) {
		ri.Printf(PRINT_WARNING, "R_LoadIQM: %s is a unsupported IQM version (%d), only version %d is supported.\n",
				mod_name, header->version, IQM_VERSION);
		return false;
	}

	LL( header->filesize );
	if( header->filesize > filesize || header->filesize > 16<<20 ) {
		return false;
	}

	LL( header->flags );
	LL( header->num_text );
	LL( header->ofs_text );
	LL( header->num_meshes );
	LL( header->ofs_meshes );
	LL( header->num_vertexarrays );
	LL( header->num_vertexes );
	LL( header->ofs_vertexarrays );
	LL( header->num_triangles );
	LL( header->ofs_triangles );
	LL( header->ofs_adjacency );
	LL( header->num_joints );
	LL( header->ofs_joints );
	LL( header->num_poses );
	LL( header->ofs_poses );
	LL( header->num_anims );
	LL( header->ofs_anims );
	LL( header->num_frames );
	LL( header->num_framechannels );
	LL( header->ofs_frames );
	LL( header->ofs_bounds );
	LL( header->num_comment );
	LL( header->ofs_comment );
	LL( header->num_extensions );
	LL( header->ofs_extensions );

	// check ioq3 joint limit
	if ( header->num_joints > IQM_MAX_JOINTS ) {
		ri.Printf(PRINT_WARNING, "R_LoadIQM: %s has more than %d joints (%d).\n",
				mod_name, IQM_MAX_JOINTS, header->num_joints);
		return false;
	}

	blendIndexesType = blendWeightsType = IQM_UBYTE;

	// check and swap vertex arrays
	if( IQM_CheckRange( header, header->ofs_vertexarrays,
			    header->num_vertexarrays,
			    sizeof(iqmVertexArray_t) ) ) {
		return false;
	}
	vertexarray = (iqmVertexArray_t *)((byte *)header + header->ofs_vertexarrays);
	for( i = 0; i < header->num_vertexarrays; i++, vertexarray++ ) {
		int n, *intPtr;

		if( vertexarray->size <= 0 || vertexarray->size > 4 ) {
			return false;
		}

		// total number of values
		n = header->num_vertexes * vertexarray->size;

		switch( vertexarray->format ) {
		case IQM_BYTE:
		case IQM_UBYTE:
			// 1 byte, no swapping necessary
			if( IQM_CheckRange( header, vertexarray->offset,
					    n, sizeof(byte) ) ) {
				return false;
			}
			break;
		case IQM_INT:
		case IQM_UINT:
		case IQM_FLOAT:
			// 4-byte swap
			if( IQM_CheckRange( header, vertexarray->offset,
					    n, sizeof(float) ) ) {
				return false;
			}
			intPtr = (int *)((byte *)header + vertexarray->offset);
			for( j = 0; j < n; j++, intPtr++ ) {
				LL( *intPtr );
			}
			break;
		default:
			// not supported
			return false;
			break;
		}

		switch( vertexarray->type ) {
		case IQM_POSITION:
		case IQM_NORMAL:
			if( vertexarray->format != IQM_FLOAT ||
			    vertexarray->size != 3 ) {
				return false;
			}
			break;
		case IQM_TANGENT:
			if( vertexarray->format != IQM_FLOAT ||
			    vertexarray->size != 4 ) {
				return false;
			}
			break;
		case IQM_TEXCOORD:
			if( vertexarray->format != IQM_FLOAT ||
			    vertexarray->size != 2 ) {
				return false;
			}
			break;
		case IQM_BLENDINDEXES:
			if( (vertexarray->format != IQM_INT &&
				 vertexarray->format != IQM_UBYTE) ||
				vertexarray->size != 4 ) {
				return false;
			}
			blendIndexesType = vertexarray->format;
			break;
		case IQM_BLENDWEIGHTS:
			if( (vertexarray->format != IQM_FLOAT &&
				 vertexarray->format != IQM_UBYTE) ||
			    vertexarray->size != 4 ) {
				return false;
			}
			blendWeightsType = vertexarray->format;
			break;
		case IQM_COLOR:
			if( vertexarray->format != IQM_UBYTE ||
			    vertexarray->size != 4 ) {
				return false;
			}
			break;
		}
	}

	// check and swap triangles
	if( IQM_CheckRange( header, header->ofs_triangles,
			    header->num_triangles, sizeof(iqmTriangle_t) ) ) {
		return false;
	}
	triangle = (iqmTriangle_t *)((byte *)header + header->ofs_triangles);
	for( i = 0; i < header->num_triangles; i++, triangle++ ) {
		LL( triangle->vertex[0] );
		LL( triangle->vertex[1] );
		LL( triangle->vertex[2] );
		
		if( triangle->vertex[0] > header->num_vertexes ||
		    triangle->vertex[1] > header->num_vertexes ||
		    triangle->vertex[2] > header->num_vertexes ) {
			return false;
		}
	}

	// check and swap meshes
	if( IQM_CheckRange( header, header->ofs_meshes,
			    header->num_meshes, sizeof(iqmMesh_t) ) ) {
		return false;
	}
	mesh = (iqmMesh_t *)((byte *)header + header->ofs_meshes);
	for( i = 0; i < header->num_meshes; i++, mesh++) {
		LL( mesh->name );
		LL( mesh->material );
		LL( mesh->first_vertex );
		LL( mesh->num_vertexes );
		LL( mesh->first_triangle );
		LL( mesh->num_triangles );

		if ( mesh->name < header->num_text ) {
			Q_strncpyz( meshName, (char*)header + header->ofs_text + mesh->name, sizeof (meshName) );
		} else {
			meshName[0] = '\0';
		}

		// check ioq3 limits
		if ( mesh->num_vertexes >= SHADER_MAX_VERTEXES ) 
		{
			ri.Printf(PRINT_WARNING, "R_LoadIQM: %s has more than %i verts on %s (%i).\n",
				  mod_name, SHADER_MAX_VERTEXES - 1, meshName[0] ? meshName : "a surface",
				  mesh->num_vertexes );
			return false;
		}
		if ( mesh->num_triangles*3 >= SHADER_MAX_INDEXES ) 
		{
			ri.Printf(PRINT_WARNING, "R_LoadIQM: %s has more than %i triangles on %s (%i).\n",
				  mod_name, ( SHADER_MAX_INDEXES / 3 ) - 1, meshName[0] ? meshName : "a surface",
				  mesh->num_triangles );
			return false;
		}

		if( mesh->first_vertex >= header->num_vertexes ||
		    mesh->first_vertex + mesh->num_vertexes > header->num_vertexes ||
		    mesh->first_triangle >= header->num_triangles ||
		    mesh->first_triangle + mesh->num_triangles > header->num_triangles ||
		    mesh->name >= header->num_text ||
		    mesh->material >= header->num_text ) {
			return false;
		}
	}

	if( header->num_poses != header->num_joints && header->num_poses != 0 ) {
		ri.Printf(PRINT_WARNING, "R_LoadIQM: %s has %d poses and %d joints, must have the same number or 0 poses\n",
			  mod_name, header->num_poses, header->num_joints );
		return false;
	}

	joint_names = 0;

	if ( header->num_joints )
	{
		// check and swap joints
		if( IQM_CheckRange( header, header->ofs_joints,
					header->num_joints, sizeof(iqmJoint_t) ) ) {
			return false;
		}
		joint = (iqmJoint_t *)((byte *)header + header->ofs_joints);
		for( i = 0; i < header->num_joints; i++, joint++ ) {
			LL( joint->name );
			LL( joint->parent );
			LL( joint->translate[0] );
			LL( joint->translate[1] );
			LL( joint->translate[2] );
			LL( joint->rotate[0] );
			LL( joint->rotate[1] );
			LL( joint->rotate[2] );
			LL( joint->rotate[3] );
			LL( joint->scale[0] );
			LL( joint->scale[1] );
			LL( joint->scale[2] );

			if( joint->parent < -1 ||
				joint->parent >= (int)header->num_joints ||
				joint->name >= (int)header->num_text ) {
				return false;
			}
			joint_names += strlen( (char *)header + header->ofs_text +
						   joint->name ) + 1;
		}
	}

	if ( header->num_poses )
	{
		// check and swap poses
		if( IQM_CheckRange( header, header->ofs_poses,
					header->num_poses, sizeof(iqmPose_t) ) ) {
			return false;
		}
		pose = (iqmPose_t *)((byte *)header + header->ofs_poses);
		for( i = 0; i < header->num_poses; i++, pose++ ) {
			LL( pose->parent );
			LL( pose->mask );
			LL( pose->channeloffset[0] );
			LL( pose->channeloffset[1] );
			LL( pose->channeloffset[2] );
			LL( pose->channeloffset[3] );
			LL( pose->channeloffset[4] );
			LL( pose->channeloffset[5] );
			LL( pose->channeloffset[6] );
			LL( pose->channeloffset[7] );
			LL( pose->channeloffset[8] );
			LL( pose->channeloffset[9] );
			LL( pose->channelscale[0] );
			LL( pose->channelscale[1] );
			LL( pose->channelscale[2] );
			LL( pose->channelscale[3] );
			LL( pose->channelscale[4] );
			LL( pose->channelscale[5] );
			LL( pose->channelscale[6] );
			LL( pose->channelscale[7] );
			LL( pose->channelscale[8] );
			LL( pose->channelscale[9] );
		}
	}

	if (header->ofs_bounds)
	{
		// check and swap model bounds
		if(IQM_CheckRange(header, header->ofs_bounds,
				  header->num_frames, sizeof(*bounds)))
		{
			return false;
		}
		bounds = (iqmBounds_t *) ((byte *) header + header->ofs_bounds);
		for(i = 0; i < header->num_frames; i++)
		{
			LL(bounds->bbmin[0]);
			LL(bounds->bbmin[1]);
			LL(bounds->bbmin[2]);
			LL(bounds->bbmax[0]);
			LL(bounds->bbmax[1]);
			LL(bounds->bbmax[2]);

			bounds++;
		}
	}

	// allocate the model and copy the data
	size = sizeof(iqmData_t);
	size += header->num_meshes * sizeof( srfIQModel_t );
	size += header->num_joints * 12 * sizeof( float ); // joint mats
	size += header->num_poses * header->num_frames * 12 * sizeof( float ); // pose mats
	if(header->ofs_bounds)
		size += header->num_frames * 6 * sizeof(float);	// model bounds
	size += header->num_vertexes * 3 * sizeof(float);	// positions
	size += header->num_vertexes * 2 * sizeof(float);	// texcoords
	size += header->num_vertexes * 3 * sizeof(float);	// normals
	size += header->num_vertexes * 4 * sizeof(float);	// tangents
	size += header->num_vertexes * 4 * sizeof(byte);	// blendIndexes
	size += header->num_vertexes * 4 * sizeof(byte);	// colors
	size += header->num_joints * sizeof(int);		// parents
	size += header->num_triangles * 3 * sizeof(int);	// triangles
	size += joint_names;					// joint names

	// blendWeights
	if (blendWeightsType == IQM_FLOAT) {
		size += header->num_vertexes * 4 * sizeof(float);
	} else {
		size += header->num_vertexes * 4 * sizeof(byte);
	}

	mod->type = MOD_IQM;
	iqmData = (iqmData_t *)ri.Hunk_Alloc( size, h_low );
	mod->modelData = iqmData;

	// fill header
	iqmData->num_vertexes = header->num_vertexes;
	iqmData->num_triangles = header->num_triangles;
	iqmData->num_frames   = header->num_frames;
	iqmData->num_surfaces = header->num_meshes;
	iqmData->num_joints   = header->num_joints;
	iqmData->num_poses   = header->num_poses;
	iqmData->blendWeightsType = blendWeightsType;
	iqmData->surfaces     = (srfIQModel_t *)(iqmData + 1);
	iqmData->jointMats    = (float *) (iqmData->surfaces + iqmData->num_surfaces);
	iqmData->poseMats     = iqmData->jointMats + 12 * header->num_joints;
	if(header->ofs_bounds)
	{
		iqmData->bounds       = iqmData->poseMats + 12 * header->num_poses * header->num_frames;
		iqmData->positions    = iqmData->bounds + 6 * header->num_frames;
	}
	else
		iqmData->positions    = iqmData->poseMats + 12 * header->num_poses * header->num_frames;
	iqmData->texcoords    = iqmData->positions + 3 * header->num_vertexes;
	iqmData->normals      = iqmData->texcoords + 2 * header->num_vertexes;
	iqmData->tangents     = iqmData->normals + 3 * header->num_vertexes;
	iqmData->blendIndexes = (byte *)(iqmData->tangents + 4 * header->num_vertexes);

	if(blendWeightsType == IQM_FLOAT) {
		iqmData->blendWeights.f = (float *)(iqmData->blendIndexes + 4 * header->num_vertexes);
		iqmData->colors		= (byte *)(iqmData->blendWeights.f + 4 * header->num_vertexes);
	} else {
		iqmData->blendWeights.b = iqmData->blendIndexes + 4 * header->num_vertexes;
		iqmData->colors		= iqmData->blendWeights.b + 4 * header->num_vertexes;
	}

	iqmData->jointParents = (int *)(iqmData->colors + 4 * header->num_vertexes);
	iqmData->triangles    = iqmData->jointParents + header->num_joints;
	iqmData->names        = (char *)(iqmData->triangles + 3 * header->num_triangles);

	if ( header->num_joints == 0 )
		iqmData->jointMats = NULL;

	if ( header->num_poses == 0 )
		iqmData->poseMats = NULL;

	// calculate joint matrices and their inverses
	// joint inverses are needed only until the pose matrices are calculated
	mat = iqmData->jointMats;
	matInv = jointInvMats;
	joint = (iqmJoint_t *)((byte *)header + header->ofs_joints);
	for( i = 0; i < header->num_joints; i++, joint++ ) {
		float baseFrame[12], invBaseFrame[12];

		JointToMatrix( joint->rotate, joint->scale, joint->translate, baseFrame );
		Matrix34Invert( baseFrame, invBaseFrame );

		if ( joint->parent >= 0 )
		{
			Matrix34Multiply( iqmData->jointMats + 12 * joint->parent, baseFrame, mat );
			mat += 12;
			Matrix34Multiply( invBaseFrame, jointInvMats + 12 * joint->parent, matInv );
			matInv += 12;
		}
		else
		{
			Com_Memcpy( mat, baseFrame,    sizeof(baseFrame)    );
			mat += 12;
			Com_Memcpy( matInv, invBaseFrame, sizeof(invBaseFrame) );
			matInv += 12;
		}
	}

	// calculate pose matrices
	framedata = (unsigned short *)((byte *)header + header->ofs_frames);
	mat = iqmData->poseMats;
	for( i = 0; i < header->num_frames; i++ ) {
		pose = (iqmPose_t *)((byte *)header + header->ofs_poses);
		for( j = 0; j < header->num_poses; j++, pose++ ) {
			vec3_t	translate;
			vec4_t	rotate;
			vec3_t	scale;
			float	mat1[12], mat2[12];

			translate[0] = pose->channeloffset[0];
			if( pose->mask & 0x001)
				translate[0] += *framedata++ * pose->channelscale[0];
			translate[1] = pose->channeloffset[1];
			if( pose->mask & 0x002)
				translate[1] += *framedata++ * pose->channelscale[1];
			translate[2] = pose->channeloffset[2];
			if( pose->mask & 0x004)
				translate[2] += *framedata++ * pose->channelscale[2];

			rotate[0] = pose->channeloffset[3];
			if( pose->mask & 0x008)
				rotate[0] += *framedata++ * pose->channelscale[3];
			rotate[1] = pose->channeloffset[4];
			if( pose->mask & 0x010)
				rotate[1] += *framedata++ * pose->channelscale[4];
			rotate[2] = pose->channeloffset[5];
			if( pose->mask & 0x020)
				rotate[2] += *framedata++ * pose->channelscale[5];
			rotate[3] = pose->channeloffset[6];
			if( pose->mask & 0x040)
				rotate[3] += *framedata++ * pose->channelscale[6];

			scale[0] = pose->channeloffset[7];
			if( pose->mask & 0x080)
				scale[0] += *framedata++ * pose->channelscale[7];
			scale[1] = pose->channeloffset[8];
			if( pose->mask & 0x100)
				scale[1] += *framedata++ * pose->channelscale[8];
			scale[2] = pose->channeloffset[9];
			if( pose->mask & 0x200)
				scale[2] += *framedata++ * pose->channelscale[9];

			// construct transformation matrix
			JointToMatrix( rotate, scale, translate, mat1 );
			
			if( pose->parent >= 0 ) {
				Matrix34Multiply( iqmData->jointMats + 12 * pose->parent,
						  mat1, mat2 );
			} else {
				Com_Memcpy( mat2, mat1, sizeof(mat1) );
			}
			
			Matrix34Multiply( mat2, jointInvMats + 12 * j, mat );
			mat += 12;
		}
	}

	// register shaders
	// overwrite the material offset with the shader index
	mesh = (iqmMesh_t *)((byte *)header + header->ofs_meshes);
	surface = iqmData->surfaces;
	str = (char *)header + header->ofs_text;
	for( i = 0; i < header->num_meshes; i++, mesh++, surface++ ) {
		surface->surfaceType = SF_IQM;
		Q_strncpyz(surface->name, str + mesh->name, sizeof (surface->name));
		Q_strlwr(surface->name); // lowercase the surface name so skin compares are faster
		surface->shader = R_FindShader( str + mesh->material, LIGHTMAP_NONE, true );
		if( surface->shader->defaultShader )
			surface->shader = tr.defaultShader;
		surface->data = iqmData;
		surface->first_vertex = mesh->first_vertex;
		surface->num_vertexes = mesh->num_vertexes;
		surface->first_triangle = mesh->first_triangle;
		surface->num_triangles = mesh->num_triangles;
	}

	// copy vertexarrays and indexes
	vertexarray = (iqmVertexArray_t *)((byte *)header + header->ofs_vertexarrays);
	for( i = 0; i < header->num_vertexarrays; i++, vertexarray++ ) {
		int	n;

		// total number of values
		n = header->num_vertexes * vertexarray->size;

		switch( vertexarray->type ) {
		case IQM_POSITION:
			Com_Memcpy( iqmData->positions,
				    (byte *)header + vertexarray->offset,
				    n * sizeof(float) );
			break;
		case IQM_NORMAL:
			Com_Memcpy( iqmData->normals,
				    (byte *)header + vertexarray->offset,
				    n * sizeof(float) );
			break;
		case IQM_TANGENT:
			Com_Memcpy( iqmData->tangents,
				    (byte *)header + vertexarray->offset,
				    n * sizeof(float) );
			break;
		case IQM_TEXCOORD:
			Com_Memcpy( iqmData->texcoords,
				    (byte *)header + vertexarray->offset,
				    n * sizeof(float) );
			break;
		case IQM_BLENDINDEXES:
			if( blendIndexesType == IQM_INT ) {
				int *data = (int*)((byte*)header + vertexarray->offset);
				for ( j = 0; j < n; j++ ) {
					iqmData->blendIndexes[j] = (byte)data[j];
				}
			} else {
				Com_Memcpy( iqmData->blendIndexes,
						(byte *)header + vertexarray->offset,
						n * sizeof(byte) );
			}
			break;
		case IQM_BLENDWEIGHTS:
			if( blendWeightsType == IQM_FLOAT ) {
				Com_Memcpy( iqmData->blendWeights.f,
						(byte *)header + vertexarray->offset,
						n * sizeof(float) );
			} else {
				Com_Memcpy( iqmData->blendWeights.b,
						(byte *)header + vertexarray->offset,
						n * sizeof(byte) );
			}
			break;
		case IQM_COLOR:
			Com_Memcpy( iqmData->colors,
				    (byte *)header + vertexarray->offset,
				    n * sizeof(byte) );
			break;
		}
	}

	// copy joint parents
	joint = (iqmJoint_t *)((byte *)header + header->ofs_joints);
	for( i = 0; i < header->num_joints; i++, joint++ ) {
		iqmData->jointParents[i] = joint->parent;
	}

	// copy triangles
	triangle = (iqmTriangle_t *)((byte *)header + header->ofs_triangles);
	for( i = 0; i < header->num_triangles; i++, triangle++ ) {
		iqmData->triangles[3*i+0] = triangle->vertex[0];
		iqmData->triangles[3*i+1] = triangle->vertex[1];
		iqmData->triangles[3*i+2] = triangle->vertex[2];
	}

	// copy joint names
	str = iqmData->names;
	joint = (iqmJoint_t *)((byte *)header + header->ofs_joints);
	for( i = 0; i < header->num_joints; i++, joint++ ) {
		char *name = (char *)header + header->ofs_text +
			joint->name;
		int len = strlen( name ) + 1;
		Com_Memcpy( str, name, len );
		str += len;
	}

	// copy model bounds
	if(header->ofs_bounds)
	{
		mat = iqmData->bounds;
		bounds = (iqmBounds_t *) ((byte *) header + header->ofs_bounds);
		for(i = 0; i < header->num_frames; i++)
		{
			mat[0] = bounds->bbmin[0];
			mat[1] = bounds->bbmin[1];
			mat[2] = bounds->bbmin[2];
			mat[3] = bounds->bbmax[0];
			mat[4] = bounds->bbmax[1];
			mat[5] = bounds->bbmax[2];

			mat += 6;
			bounds++;
		}
	}

	return true;
}

/*
=============
R_CullIQM
=============
*/
static int R_CullIQM( iqmData_t *data, trRefEntity_t *ent ) {
	vec3_t		bounds[2];
	vec_t		*oldBounds, *newBounds;
	int		i;

	if (!data->bounds) {
		tr.pc.c_box_cull_md3_clip++;
		return CULL_CLIP;
	}

	// compute bounds pointers
	oldBounds = data->bounds + 6*ent->e.oldframe;
	newBounds = data->bounds + 6*ent->e.frame;

	// calculate a bounding box in the current coordinate system
	for (i = 0 ; i < 3 ; i++) {
		bounds[0][i] = oldBounds[i] < newBounds[i] ? oldBounds[i] : newBounds[i];
		bounds[1][i] = oldBounds[i+3] > newBounds[i+3] ? oldBounds[i+3] : newBounds[i+3];
	}

	switch ( R_CullLocalBox( bounds ) )
	{
	case CULL_IN:
		tr.pc.c_box_cull_md3_in++;
		return CULL_IN;
	case CULL_CLIP:
		tr.pc.c_box_cull_md3_clip++;
		return CULL_CLIP;
	case CULL_OUT:
	default:
		tr.pc.c_box_cull_md3_out++;
		return CULL_OUT;
	}
}

/*
=================
R_ComputeIQMFogNum

=================
*/
int R_ComputeIQMFogNum( iqmData_t *data, trRefEntity_t *ent ) {
	int			i, j;
	fog_t			*fog;
	const vec_t		*bounds;
	const vec_t		defaultBounds[6] = { -8, -8, -8, 8, 8, 8 };
	vec3_t			diag, center;
	vec3_t			localOrigin;
	vec_t			radius;

	if ( tr.refdef.rdflags & RDF_NOWORLDMODEL ) {
		return 0;
	}

	// FIXME: non-normalized axis issues
	if (data->bounds) {
		bounds = data->bounds + 6*ent->e.frame;
	} else {
		bounds = defaultBounds;
	}
	VectorSubtract( bounds+3, bounds, diag );
	VectorMA( bounds, 0.5f, diag, center );
	VectorAdd( ent->e.origin, center, localOrigin );
	radius = 0.5f * VectorLength( diag );

	for ( i = 1 ; i < tr.world->numfogs ; i++ ) {
		fog = &tr.world->fogs[i];
		for ( j = 0 ; j < 3 ; j++ ) {
			if ( localOrigin[j] - radius >= fog->bounds[1][j] ) {
				break;
			}
			if ( localOrigin[j] + radius <= fog->bounds[0][j] ) {
				break;
			}
		}
		if ( j == 3 ) {
			return i;
		}
	}

	return 0;
}

/*
=================
R_AddIQMSurfaces

Add all surfaces of this model
=================
*/
void R_AddIQMSurfaces( trRefEntity_t *ent ) {
	iqmData_t		*data;
	srfIQModel_t		*surface;
	int			i, j;
	bool		personalModel;
	int			cull;
	int			fogNum;
	shader_t		*shader;
	skin_t			*skin;

	data = (iqmData_t*)tr.currentModel->modelData;
	surface = data->surfaces;

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

	if ( ent->e.renderfx & RF_WRAP_FRAMES ) {
		ent->e.frame %= data->num_frames;
		ent->e.oldframe %= data->num_frames;
	}

	//
	// 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 >= data->num_frames) 
	     || (ent->e.frame < 0)
	     || (ent->e.oldframe >= data->num_frames)
	     || (ent->e.oldframe < 0) ) {
		ri.Printf( PRINT_DEVELOPER, "R_AddIQMSurfaces: 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;
	}

	//
	// cull the entire model if merged bounding box of both frames
	// is outside the view frustum.
	//
	cull = R_CullIQM ( data, ent );
	if ( cull == CULL_OUT ) {
		return;
	}

	//
	// set up lighting now that we know we aren't culled
	//
	if ( !personalModel || r_shadows->integer > 1 ) {
		R_SetupEntityLighting( &tr.refdef, ent );
	}

	//
	// see if we are in a fog volume
	//
	fogNum = R_ComputeIQMFogNum( data, ent );

	for ( i = 0 ; i < data->num_surfaces ; i++ ) {
		if(ent->e.customShader)
			shader = R_GetShaderByHandle( ent->e.customShader );
		else if(ent->e.customSkin > 0 && ent->e.customSkin < tr.numSkins)
		{
			skin = R_GetSkinByHandle(ent->e.customSkin);
			shader = tr.defaultShader;

			for(j = 0; j < skin->numSurfaces; j++)
			{
				if (!strcmp(skin->surfaces[j].name, surface->name))
				{
					shader = skin->surfaces[j].shader;
					break;
				}
			}
		} else {
			shader = surface->shader;
		}

		// we will add shadows even if the main object isn't visible in the view

		// stencil shadows can't do personal models unless I polyhedron clip
		if ( !personalModel
			&& r_shadows->integer == 2 
			&& fogNum == 0
			&& !(ent->e.renderfx & ( RF_NOSHADOW | RF_DEPTHHACK ) ) 
			&& shader->sort == SS_OPAQUE ) {
			R_AddDrawSurf( (surfaceType_t*)surface, tr.shadowShader, 0, 0 );
		}

		// projection shadows work fine with personal models
		if ( r_shadows->integer == 3
			&& fogNum == 0
			&& (ent->e.renderfx & RF_SHADOW_PLANE )
			&& shader->sort == SS_OPAQUE ) {
			R_AddDrawSurf( (surfaceType_t*)surface, tr.projectionShadowShader, 0, 0 );
		}

		if( !personalModel ) {
			R_AddDrawSurf( (surfaceType_t*)surface, shader, fogNum, 0 );
		}

		surface++;
	}
}


static void ComputePoseMats( iqmData_t *data, int frame, int oldframe,
			      float backlerp, float *mat ) {
	float	*mat1, *mat2;
	int	*joint = data->jointParents;
	int	i;

	if ( data->num_poses == 0 ) {
		for( i = 0; i < data->num_joints; i++, joint++ ) {
			if( *joint >= 0 ) {
				Matrix34Multiply( mat + 12 * *joint,
						  identityMatrix, mat + 12*i );
			} else {
				Com_Memcpy( mat + 12*i, identityMatrix, 12 * sizeof(float) );
			}
		}
		return;
	}

	if ( oldframe == frame ) {
		mat1 = data->poseMats + 12 * data->num_poses * frame;
		for( i = 0; i < data->num_poses; i++, joint++ ) {
			if( *joint >= 0 ) {
				Matrix34Multiply( mat + 12 * *joint,
						  mat1 + 12*i, mat + 12*i );
			} else {
				Com_Memcpy( mat + 12*i, mat1 + 12*i, 12 * sizeof(float) );
			}
		}
	} else  {
		mat1 = data->poseMats + 12 * data->num_poses * frame;
		mat2 = data->poseMats + 12 * data->num_poses * oldframe;
		
		for( i = 0; i < data->num_poses; i++, joint++ ) {
			if( *joint >= 0 ) {
				float tmpMat[12];
				InterpolateMatrix( mat1 + 12*i, mat2 + 12*i,
						   backlerp, tmpMat );
				Matrix34Multiply( mat + 12 * *joint,
						  tmpMat, mat + 12*i );
				
			} else {
				InterpolateMatrix( mat1 + 12*i, mat2 + 12*i,
						   backlerp, mat );
			}
		}
	}
}

static void ComputeJointMats( iqmData_t *data, int frame, int oldframe,
			      float backlerp, float *mat ) {
	float	*mat1;
	int	i;

	ComputePoseMats( data, frame, oldframe, backlerp, mat );

	for( i = 0; i < data->num_joints; i++ ) {
		float outmat[12];
		mat1 = mat + 12 * i;

		Com_Memcpy(outmat, mat1, sizeof(outmat));

		Matrix34Multiply_OnlySetOrigin( outmat, data->jointMats + 12 * i, mat1 );
	}
}


/*
=================
RB_AddIQMSurfaces

Compute vertices for this model surface
=================
*/
void RB_IQMSurfaceAnim( surfaceType_t *surface ) {
	srfIQModel_t	*surf = (srfIQModel_t *)surface;
	iqmData_t	*data = surf->data;
	float		jointMats[IQM_MAX_JOINTS * 12];
	int		i;

	vec4_t		*outXYZ;
	vec4_t		*outNormal;
	vec2_t		(*outTexCoord)[2];
	color4ub_t	*outColor;

	int	frame = data->num_frames ? backEnd.currentEntity->e.frame % data->num_frames : 0;
	int	oldframe = data->num_frames ? backEnd.currentEntity->e.oldframe % data->num_frames : 0;
	float	backlerp = backEnd.currentEntity->e.backlerp;

	int		*tri;
	glIndex_t	*ptr;
	glIndex_t	base;

	RB_CHECKOVERFLOW( surf->num_vertexes, surf->num_triangles * 3 );

	outXYZ = &tess.xyz[tess.numVertexes];
	outNormal = &tess.normal[tess.numVertexes];
	outTexCoord = &tess.texCoords[tess.numVertexes];
	outColor = &tess.vertexColors[tess.numVertexes];

	// compute interpolated joint matrices
	if ( data->num_poses > 0 ) {
		ComputePoseMats( data, frame, oldframe, backlerp, jointMats );
	}

	// transform vertexes and fill other data
	for( i = 0; i < surf->num_vertexes;
	     i++, outXYZ++, outNormal++, outTexCoord++, outColor++ ) {
		int	j, k;
		float	vtxMat[12];
		float	nrmMat[9];
		int	vtx = i + surf->first_vertex;
		float	blendWeights[4];
		int		numWeights;

		for ( numWeights = 0; numWeights < 4; numWeights++ ) {
			if ( data->blendWeightsType == IQM_FLOAT )
				blendWeights[numWeights] = data->blendWeights.f[4*vtx + numWeights];
			else
				blendWeights[numWeights] = (float)data->blendWeights.b[4*vtx + numWeights] / 255.0f;

			if ( blendWeights[numWeights] <= 0 )
				break;
		}

		if ( data->num_poses == 0 || numWeights == 0 ) {
			// no blend joint, use identity matrix.
			Com_Memcpy( vtxMat, identityMatrix, 12 * sizeof (float) );
		} else {
			// compute the vertex matrix by blending the up to
			// four blend weights
			Com_Memset( vtxMat, 0, 12 * sizeof (float) );
			for( j = 0; j < numWeights; j++ ) {
				for( k = 0; k < 12; k++ ) {
					vtxMat[k] += blendWeights[j] * jointMats[12*data->blendIndexes[4*vtx + j] + k];
				}
			}
		}

		// compute the normal matrix as transpose of the adjoint
		// of the vertex matrix
		nrmMat[ 0] = vtxMat[ 5]*vtxMat[10] - vtxMat[ 6]*vtxMat[ 9];
		nrmMat[ 1] = vtxMat[ 6]*vtxMat[ 8] - vtxMat[ 4]*vtxMat[10];
		nrmMat[ 2] = vtxMat[ 4]*vtxMat[ 9] - vtxMat[ 5]*vtxMat[ 8];
		nrmMat[ 3] = vtxMat[ 2]*vtxMat[ 9] - vtxMat[ 1]*vtxMat[10];
		nrmMat[ 4] = vtxMat[ 0]*vtxMat[10] - vtxMat[ 2]*vtxMat[ 8];
		nrmMat[ 5] = vtxMat[ 1]*vtxMat[ 8] - vtxMat[ 0]*vtxMat[ 9];
		nrmMat[ 6] = vtxMat[ 1]*vtxMat[ 6] - vtxMat[ 2]*vtxMat[ 5];
		nrmMat[ 7] = vtxMat[ 2]*vtxMat[ 4] - vtxMat[ 0]*vtxMat[ 6];
		nrmMat[ 8] = vtxMat[ 0]*vtxMat[ 5] - vtxMat[ 1]*vtxMat[ 4];

		(*outTexCoord)[0][0] = data->texcoords[2*vtx + 0];
		(*outTexCoord)[0][1] = data->texcoords[2*vtx + 1];
		(*outTexCoord)[1][0] = (*outTexCoord)[0][0];
		(*outTexCoord)[1][1] = (*outTexCoord)[0][1];

		(*outXYZ)[0] =
			vtxMat[ 0] * data->positions[3*vtx+0] +
			vtxMat[ 1] * data->positions[3*vtx+1] +
			vtxMat[ 2] * data->positions[3*vtx+2] +
			vtxMat[ 3];
		(*outXYZ)[1] =
			vtxMat[ 4] * data->positions[3*vtx+0] +
			vtxMat[ 5] * data->positions[3*vtx+1] +
			vtxMat[ 6] * data->positions[3*vtx+2] +
			vtxMat[ 7];
		(*outXYZ)[2] =
			vtxMat[ 8] * data->positions[3*vtx+0] +
			vtxMat[ 9] * data->positions[3*vtx+1] +
			vtxMat[10] * data->positions[3*vtx+2] +
			vtxMat[11];
		(*outXYZ)[3] = 1.0f;

		(*outNormal)[0] =
			nrmMat[ 0] * data->normals[3*vtx+0] +
			nrmMat[ 1] * data->normals[3*vtx+1] +
			nrmMat[ 2] * data->normals[3*vtx+2];
		(*outNormal)[1] =
			nrmMat[ 3] * data->normals[3*vtx+0] +
			nrmMat[ 4] * data->normals[3*vtx+1] +
			nrmMat[ 5] * data->normals[3*vtx+2];
		(*outNormal)[2] =
			nrmMat[ 6] * data->normals[3*vtx+0] +
			nrmMat[ 7] * data->normals[3*vtx+1] +
			nrmMat[ 8] * data->normals[3*vtx+2];
		(*outNormal)[3] = 0.0f;

		(*outColor)[0] = data->colors[4*vtx+0];
		(*outColor)[1] = data->colors[4*vtx+1];
		(*outColor)[2] = data->colors[4*vtx+2];
		(*outColor)[3] = data->colors[4*vtx+3];
	}

	tri = data->triangles + 3 * surf->first_triangle;
	ptr = &tess.indexes[tess.numIndexes];
	base = tess.numVertexes;

	for( i = 0; i < surf->num_triangles; i++ ) {
		*ptr++ = base + (*tri++ - surf->first_vertex);
		*ptr++ = base + (*tri++ - surf->first_vertex);
		*ptr++ = base + (*tri++ - surf->first_vertex);
	}

	tess.numIndexes += 3 * surf->num_triangles;
	tess.numVertexes += surf->num_vertexes;
}

int R_IQMLerpTag( orientation_t *tag, iqmData_t *data,
		  int startFrame, int endFrame, 
		  float frac, const char *tagName ) {
	float	jointMats[IQM_MAX_JOINTS * 12];
	int	joint;
	char	*names = data->names;

	// get joint number by reading the joint names
	for( joint = 0; joint < data->num_joints; joint++ ) {
		if( !strcmp( tagName, names ) )
			break;
		names += strlen( names ) + 1;
	}
	if( joint >= data->num_joints ) {
		AxisClear( tag->axis );
		VectorClear( tag->origin );
		return false;
	}

	ComputeJointMats( data, startFrame, endFrame, frac, jointMats );

	tag->axis[0][0] = jointMats[12 * joint + 0];
	tag->axis[1][0] = jointMats[12 * joint + 1];
	tag->axis[2][0] = jointMats[12 * joint + 2];
	tag->origin[0] = jointMats[12 * joint + 3];
	tag->axis[0][1] = jointMats[12 * joint + 4];
	tag->axis[1][1] = jointMats[12 * joint + 5];
	tag->axis[2][1] = jointMats[12 * joint + 6];
	tag->origin[1] = jointMats[12 * joint + 7];
	tag->axis[0][2] = jointMats[12 * joint + 8];
	tag->axis[1][2] = jointMats[12 * joint + 9];
	tag->axis[2][2] = jointMats[12 * joint + 10];
	tag->origin[2] = jointMats[12 * joint + 11];

	return true;
}