MikktspaceWrap.h

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/* Copyright (C) 2012 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. 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.
 *
 * 0 A.D. 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 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_MIKKWRAP
#define INCLUDED_MIKKWRAP


#include "third_party/mikktspace/mikktspace.h"

// Disable useless MSVC warning
#if MSC_VERSION
# pragma warning(disable:4512) // "assignment operator could not be generated"
#endif

class MikkTSpace
{

public:
    
    MikkTSpace(const CModelDefPtr& m, std::vector<float>& v, bool gpuSkinning);

    void generate();
    
private:
    
    SMikkTSpaceInterface m_Interface;
    SMikkTSpaceContext m_Context;

    const CModelDefPtr& m_Model;

    std::vector<float>& m_NewVertices;
    bool m_GpuSkinning;
    

    // Returns the number of faces (triangles/quads) on the mesh to be processed.
    static int getNumFaces(const SMikkTSpaceContext *pContext);


    // Returns the number of vertices on face number iFace
    // iFace is a number in the range {0, 1, ..., getNumFaces()-1}
    static int getNumVerticesOfFace(const SMikkTSpaceContext *pContext, const int iFace);


    // returns the position/normal/texcoord of the referenced face of vertex number iVert.
    // iVert is in the range {0,1,2} for triangles and {0,1,2,3} for quads.
    static void getPosition(const SMikkTSpaceContext *pContext, 
            float fvPosOut[], const int iFace, const int iVert);

    static void getNormal(const SMikkTSpaceContext *pContext, 
            float fvNormOut[], const int iFace, const int iVert);

    static void getTexCoord(const SMikkTSpaceContext *pContext, 
            float fvTexcOut[], const int iFace, const int iVert);


    // This function is used to return tangent space results to the application.
    // fvTangent and fvBiTangent are unit length vectors and fMagS and fMagT are their
    // true magnitudes which can be used for relief mapping effects.
    // fvBiTangent is the "real" bitangent and thus may not be perpendicular to fvTangent.
    // However, both are perpendicular to the vertex normal.
    // For normal maps it is sufficient to use the following simplified version of the bitangent which is generated at pixel/vertex level.
    // fSign = bIsOrientationPreserving ? 1.0f : (-1.0f);
    // bitangent = fSign * cross(vN, tangent);
    static void setTSpace(const SMikkTSpaceContext * pContext, const float fvTangent[], 
            const float fvBiTangent[], const float fMagS, const float fMagT, 
            const tbool bIsOrientationPreserving, const int iFace, const int iVert);


};


#endif // INCLUDED_MIKKWRAP