gpuhelper.h

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// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_GPUHELPER_H
#define EIGEN_GPUHELPER_H

#include <Eigen/Geometry>
#include <GL/gl.h>
#include <vector>

using namespace Eigen;

typedef Vector4f Color;

class GpuHelper
{
  public:

    GpuHelper();

    ~GpuHelper();

    enum ProjectionMode2D { PM_Normalized = 1, PM_Viewport = 2 };
    void pushProjectionMode2D(ProjectionMode2D pm);
    void popProjectionMode2D();

    template<typename Scalar, int _Flags>
    void multMatrix(const Matrix<Scalar,4,4, _Flags, 4,4>& mat, GLenum matrixTarget);

    template<typename Scalar, int _Flags>
    void loadMatrix(const Eigen::Matrix<Scalar,4,4, _Flags, 4,4>& mat, GLenum matrixTarget);

    template<typename Scalar, typename Derived>
    void loadMatrix(
        const Eigen::CwiseNullaryOp<Eigen::internal::scalar_identity_op<Scalar>,Derived>&,
        GLenum matrixTarget);

    inline void forceMatrixTarget(GLenum matrixTarget) {glMatrixMode(mCurrentMatrixTarget=matrixTarget);}

    inline void setMatrixTarget(GLenum matrixTarget);

    template<typename Scalar, int _Flags>
    inline void pushMatrix(const Matrix<Scalar,4,4, _Flags, 4,4>& mat, GLenum matrixTarget);

    template<typename Scalar, typename Derived>
    void pushMatrix(
        const Eigen::CwiseNullaryOp<Eigen::internal::scalar_identity_op<Scalar>,Derived>&,
        GLenum matrixTarget);

    inline void pushMatrix(GLenum matrixTarget);

    inline void popMatrix(GLenum matrixTarget);

    void drawVector(const Vector3f& position, const Vector3f& vec, const Color& color, float aspect = 50.);
    void drawVectorBox(const Vector3f& position, const Vector3f& vec, const Color& color, float aspect = 50.);
    void drawUnitCube(void);
    void drawUnitSphere(int level=0);

    inline void draw(GLenum mode, uint nofElement);

    inline void draw(GLenum mode, uint start, uint end);

    inline void draw(GLenum mode, const std::vector<uint>* pIndexes);

protected:

    void update(void);

    GLuint mColorBufferId;
    int mVpWidth, mVpHeight;
    GLenum mCurrentMatrixTarget;
    bool mInitialized;
};

extern GpuHelper gpu;


template<bool RowMajor, int _Flags> struct GlMatrixHelper;

template<int _Flags> struct GlMatrixHelper<false,_Flags>
{
    static void loadMatrix(const Matrix<float, 4,4, _Flags, 4,4>&  mat) { glLoadMatrixf(mat.data()); }
    static void loadMatrix(const Matrix<double,4,4, _Flags, 4,4>& mat) { glLoadMatrixd(mat.data()); }
    static void multMatrix(const Matrix<float, 4,4, _Flags, 4,4>&  mat) { glMultMatrixf(mat.data()); }
    static void multMatrix(const Matrix<double,4,4, _Flags, 4,4>& mat) { glMultMatrixd(mat.data()); }
};

template<int _Flags> struct GlMatrixHelper<true,_Flags>
{
    static void loadMatrix(const Matrix<float, 4,4, _Flags, 4,4>&  mat) { glLoadMatrixf(mat.transpose().eval().data()); }
    static void loadMatrix(const Matrix<double,4,4, _Flags, 4,4>& mat) { glLoadMatrixd(mat.transpose().eval().data()); }
    static void multMatrix(const Matrix<float, 4,4, _Flags, 4,4>&  mat) { glMultMatrixf(mat.transpose().eval().data()); }
    static void multMatrix(const Matrix<double,4,4, _Flags, 4,4>& mat) { glMultMatrixd(mat.transpose().eval().data()); }
};

inline void GpuHelper::setMatrixTarget(GLenum matrixTarget)
{
    if (matrixTarget != mCurrentMatrixTarget)
        glMatrixMode(mCurrentMatrixTarget=matrixTarget);
}

template<typename Scalar, int _Flags>
void GpuHelper::multMatrix(const Matrix<Scalar,4,4, _Flags, 4,4>& mat, GLenum matrixTarget)
{
    setMatrixTarget(matrixTarget);
    GlMatrixHelper<_Flags&Eigen::RowMajorBit, _Flags>::multMatrix(mat);
}

template<typename Scalar, typename Derived>
void GpuHelper::loadMatrix(
    const Eigen::CwiseNullaryOp<Eigen::internal::scalar_identity_op<Scalar>,Derived>&,
    GLenum matrixTarget)
{
    setMatrixTarget(matrixTarget);
    glLoadIdentity();
}

template<typename Scalar, int _Flags>
void GpuHelper::loadMatrix(const Eigen::Matrix<Scalar,4,4, _Flags, 4,4>& mat, GLenum matrixTarget)
{
    setMatrixTarget(matrixTarget);
    GlMatrixHelper<(_Flags&Eigen::RowMajorBit)!=0, _Flags>::loadMatrix(mat);
}

inline void GpuHelper::pushMatrix(GLenum matrixTarget)
{
    setMatrixTarget(matrixTarget);
    glPushMatrix();
}

template<typename Scalar, int _Flags>
inline void GpuHelper::pushMatrix(const Matrix<Scalar,4,4, _Flags, 4,4>& mat, GLenum matrixTarget)
{
    pushMatrix(matrixTarget);
    GlMatrixHelper<_Flags&Eigen::RowMajorBit,_Flags>::loadMatrix(mat);
}

template<typename Scalar, typename Derived>
void GpuHelper::pushMatrix(
    const Eigen::CwiseNullaryOp<Eigen::internal::scalar_identity_op<Scalar>,Derived>&,
    GLenum matrixTarget)
{
    pushMatrix(matrixTarget);
    glLoadIdentity();
}

inline void GpuHelper::popMatrix(GLenum matrixTarget)
{
    setMatrixTarget(matrixTarget);
    glPopMatrix();
}

inline void GpuHelper::draw(GLenum mode, uint nofElement)
{
    glDrawArrays(mode, 0, nofElement);
}


inline void GpuHelper::draw(GLenum mode, const std::vector<uint>* pIndexes)
{
    glDrawElements(mode, pIndexes->size(), GL_UNSIGNED_INT, &(pIndexes->front()));
}

inline void GpuHelper::draw(GLenum mode, uint start, uint end)
{
    glDrawArrays(mode, start, end-start);
}

#endif // EIGEN_GPUHELPER_H