如何使用 glew 将 opengl 代码移植到 iPhone 的 openGL ES 代码

Question

我正在尝试将用 opengl 编写的 ogre 函数移植到 opengl ES，但该函数使用 glew.h 中的定义，并且我不知道如何移植此代码。

问题是GL_S（例如）没有声明，因为它是int glew.h，而我没有iPhone的glew.h。

这是代码：

void GLRenderSystem::_setTextureCoordCalculation(size_t stage, TexCoordCalcMethod m, 
    const Frustum* frustum)
{
    if (stage >= mFixedFunctionTextureUnits)
    {
        // Can't do this
        return;
    }


    GLfloat M[16];
    Matrix4 projectionBias;

    // Default to no extra auto texture matrix
    mUseAutoTextureMatrix = false;

    GLfloat eyePlaneS[] = {1.0, 0.0, 0.0, 0.0};
    GLfloat eyePlaneT[] = {0.0, 1.0, 0.0, 0.0};
    GLfloat eyePlaneR[] = {0.0, 0.0, 1.0, 0.0};
    GLfloat eyePlaneQ[] = {0.0, 0.0, 0.0, 1.0};

    if (!activateGLTextureUnit(stage))
        return;

    switch( m )
    {
    case TEXCALC_NONE:
        glDisable( GL_TEXTURE_GEN_S );
        glDisable( GL_TEXTURE_GEN_T );
        glDisable( GL_TEXTURE_GEN_R );
        glDisable( GL_TEXTURE_GEN_Q );
        break;

    case TEXCALC_ENVIRONMENT_MAP:
        glTexGeni( GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP );
        glTexGeni( GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP );

        glEnable( GL_TEXTURE_GEN_S );
        glEnable( GL_TEXTURE_GEN_T );
        glDisable( GL_TEXTURE_GEN_R );
        glDisable( GL_TEXTURE_GEN_Q );

        // Need to use a texture matrix to flip the spheremap
        mUseAutoTextureMatrix = true;
        memset(mAutoTextureMatrix, 0, sizeof(GLfloat)*16);
        mAutoTextureMatrix[0] = mAutoTextureMatrix[10] = mAutoTextureMatrix[15] = 1.0f;
        mAutoTextureMatrix[5] = -1.0f;

        break;

    case TEXCALC_ENVIRONMENT_MAP_PLANAR:            
        // XXX This doesn't seem right?!

ifdef GL_VERSION_1_3

        glTexGeni( GL_S, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP );
        glTexGeni( GL_T, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP );
        glTexGeni( GL_R, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP );

        glEnable( GL_TEXTURE_GEN_S );
        glEnable( GL_TEXTURE_GEN_T );
        glEnable( GL_TEXTURE_GEN_R );
        glDisable( GL_TEXTURE_GEN_Q );

else

        glTexGeni( GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP );
        glTexGeni( GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP );

        glEnable( GL_TEXTURE_GEN_S );
        glEnable( GL_TEXTURE_GEN_T );
        glDisable( GL_TEXTURE_GEN_R );
        glDisable( GL_TEXTURE_GEN_Q );

endif

        break;
    case TEXCALC_ENVIRONMENT_MAP_REFLECTION:

        glTexGeni( GL_S, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP );
        glTexGeni( GL_T, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP );
        glTexGeni( GL_R, GL_TEXTURE_GEN_MODE, GL_REFLECTION_MAP );

        glEnable( GL_TEXTURE_GEN_S );
        glEnable( GL_TEXTURE_GEN_T );
        glEnable( GL_TEXTURE_GEN_R );
        glDisable( GL_TEXTURE_GEN_Q );

        // We need an extra texture matrix here
        // This sets the texture matrix to be the inverse of the view matrix
        mUseAutoTextureMatrix = true;
        makeGLMatrix( M, mViewMatrix);

        // Transpose 3x3 in order to invert matrix (rotation)
        // Note that we need to invert the Z _before_ the rotation
        // No idea why we have to invert the Z at all, but reflection is wrong without it
        mAutoTextureMatrix[0] = M[0]; mAutoTextureMatrix[1] = M[4]; mAutoTextureMatrix[2] = -M[8];
        mAutoTextureMatrix[4] = M[1]; mAutoTextureMatrix[5] = M[5]; mAutoTextureMatrix[6] = -M[9];
        mAutoTextureMatrix[8] = M[2]; mAutoTextureMatrix[9] = M[6]; mAutoTextureMatrix[10] = -M[10];
        mAutoTextureMatrix[3] = mAutoTextureMatrix[7] = mAutoTextureMatrix[11] = 0.0f;
        mAutoTextureMatrix[12] = mAutoTextureMatrix[13] = mAutoTextureMatrix[14] = 0.0f;
        mAutoTextureMatrix[15] = 1.0f;

        break;
    case TEXCALC_ENVIRONMENT_MAP_NORMAL:
        glTexGeni( GL_S, GL_TEXTURE_GEN_MODE, GL_NORMAL_MAP );
        glTexGeni( GL_T, GL_TEXTURE_GEN_MODE, GL_NORMAL_MAP );
        glTexGeni( GL_R, GL_TEXTURE_GEN_MODE, GL_NORMAL_MAP );

        glEnable( GL_TEXTURE_GEN_S );
        glEnable( GL_TEXTURE_GEN_T );
        glEnable( GL_TEXTURE_GEN_R );
        glDisable( GL_TEXTURE_GEN_Q );
        break;
    case TEXCALC_PROJECTIVE_TEXTURE:
        glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
        glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
        glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
        glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);
        glTexGenfv(GL_S, GL_EYE_PLANE, eyePlaneS);
        glTexGenfv(GL_T, GL_EYE_PLANE, eyePlaneT);
        glTexGenfv(GL_R, GL_EYE_PLANE, eyePlaneR);
        glTexGenfv(GL_Q, GL_EYE_PLANE, eyePlaneQ);
        glEnable(GL_TEXTURE_GEN_S);
        glEnable(GL_TEXTURE_GEN_T);
        glEnable(GL_TEXTURE_GEN_R);
        glEnable(GL_TEXTURE_GEN_Q);

        mUseAutoTextureMatrix = true;

        // Set scale and translation matrix for projective textures
        projectionBias = Matrix4::CLIPSPACE2DTOIMAGESPACE;

        projectionBias = projectionBias * frustum->getProjectionMatrix();
        if(mTexProjRelative)
        {
            Matrix4 viewMatrix;
            frustum->calcViewMatrixRelative(mTexProjRelativeOrigin, viewMatrix);
            projectionBias = projectionBias * viewMatrix;
        }
        else
        {
            projectionBias = projectionBias * frustum->getViewMatrix();
        }
        projectionBias = projectionBias * mWorldMatrix;

        makeGLMatrix(mAutoTextureMatrix, projectionBias);
        break;
    default:
        break;
    }
    activateGLTextureUnit(0);
}

Answer 1

OpenGL ES 1.X 没有纹理坐标生成 。