void initReduction()
{
    reductionEffect->Bind();
    reductionEffect->Uniform("Mode", 0);
    sourceTexture->Bind(GL_TEXTURE0);
    GetWriteBuffer().BindWrite();
    drawQuad(0, 0, sourceTexture->Width(), sourceTexture->Height());
    SwapBuffers();
}

void Apply()
{
    using namespace std;
    glPushAttrib(GL_ENABLE_BIT);
    glDisable(GL_STENCIL_TEST);
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_BLEND);
    glDisable(GL_CULL_FACE);
    initReduction();
    reductionEffect->Bind();
    reductionEffect->Uniform("KernelSize", kernelSize);
    reductionEffect->Uniform("Mode", 1);
    unsigned cWidth, cHeight;

    cWidth = sourceTexture->Width() / kernelSize;
    cHeight = sourceTexture->Height() / kernelSize;

    int iter = 2;
    while(cWidth > 1 || cHeight > 1)
    {
        GetReadBuffer().BindRead(GL_TEXTURE0);
        GetWriteBuffer().BindWrite();

        reductionEffect->Uniform("Iteration", iter);
        reductionEffect->Uniform("CWidth", cWidth);
        reductionEffect->Uniform("CHeight", cHeight);
        reductionEffect->Uniform("TexelSize", fvec2( 1.0f / cWidth, 1.0f / cHeight));
        drawQuad(0, 0, cWidth, cHeight);

        cWidth = max<unsigned>(cWidth / kernelSize, 1);
        cHeight = max<unsigned>(cHeight / kernelSize, 1);

        iter *= iter;
        SwapBuffers();
    }

    glPopAttrib();
}