AntiAliasing.cc

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\*===========================================================================*/
 
 
//=============================================================================
//
//  OpenGL AntiAliasing methods
//
//=============================================================================
 
 
//== INCLUDES =================================================================
 
#include <ACG/GL/AntiAliasing.hh>
#include <ACG/GL/acg_glew.hh>
#include <ACG/ShaderUtils/GLSLShader.hh>
#include <ACG/GL/ScreenQuad.hh>
 
#include <ACG/GL/ShaderCache.hh>
 
//== DEFINES ==================================================================
 
// shader files
#define MSAA_SCREENQUAD_SHADER "ScreenQuad/screenquad.glsl"
#define MSAA_NEAREST_SHADER "MSAA/sample_nearest.glsl"
#define MSAA_NEAREST_DEPTH_SHADER "MSAA/sample_nearest_and_depth.glsl"
#define MSAA_LINEAR_SHADER "MSAA/sample_linear.glsl"
 
 
 
//== NAMESPACES ===============================================================
 
namespace ACG {
 
 
//== CLASS IMPLEMENTATION =====================================================
 
#ifdef MSFILTERWEIGHTS
 
 
MSFilterWeights::MSFilterWeights(int _numSamples) : numSamples_(_numSamples) {
 
  weights_.resize(_numSamples);
  float sumWeights = 0.0f;
 
  // texel center is at (0.5, 0.5) as specified in 
  //  http://www.opengl.org/sdk/docs/man3/xhtml/glGetMultisample.xml
  Vec2f texelCenter(0.5f, 0.5f);
 
  // query sample count of currently bound fbo to avoid error on calling glGetMultisample
  int fboSamples = 0;
  glGetIntegerv(GL_SAMPLES, &fboSamples);
 
 
  for (int i = 0; i < _numSamples; ++i) {
    GLfloat val[2];
 
    if (i < fboSamples)
      glGetMultisamplefv(GL_SAMPLE_POSITION, i, val);
    else
      val[0] = val[1] = 0.5f; // maybe output warning here
    
    Vec2f samplePosition(val[0], val[1]);
 
    // weighting based on distance to texel center
    float sampleDist = (samplePosition - texelCenter).norm();
 
    // samples close to the center are weighted higher than samples farther away
    weights_[i] = 1.0f - sampleDist;
 
    sumWeights += weights_[i];
  }
 
  // normalize weights
 
  for (int i = 0; i < _numSamples; ++i)
    weights_[i] /= sumWeights;
}
 
//=============================================================================
void MSFilterWeights::asTextureBuffer( TextureBuffer& out ) {
  if (numSamples_)
    out.setBufferData(numSamples_ * 4, &weights_[0], GL_R32F, GL_STATIC_DRAW);
}
//=============================================================================
 
#endif //MSFILTERWEIGHTS
 
 
//=============================================================================
 
#ifdef MSTEXTURESAMPLER
MSTextureSampler::MSTextureSampler() : shaderNearest_(0), shaderNearestDepth_(0), shaderLinear_(0) {
}
 
 
MSTextureSampler::~MSTextureSampler() {
  delete shaderNearest_;
  delete shaderLinear_;
  delete shaderNearestDepth_;
}
 
MSTextureSampler& MSTextureSampler::instance() {
  static MSTextureSampler singleton;
  return singleton;
}
 
//=============================================================================
 
void MSTextureSampler::init() {
  if (!shaderNearest_)
    shaderNearest_ = GLSL::loadProgram(MSAA_SCREENQUAD_SHADER, MSAA_NEAREST_SHADER);
 
  if (!shaderNearestDepth_)
    shaderNearestDepth_ = GLSL::loadProgram(MSAA_SCREENQUAD_SHADER, MSAA_NEAREST_DEPTH_SHADER);
 
  if (!shaderLinear_)
    shaderLinear_ = GLSL::loadProgram(MSAA_SCREENQUAD_SHADER, MSAA_LINEAR_SHADER);
}
 
//=============================================================================
 
void MSTextureSampler::filterMSAATexture_Nearest( GLuint _texture, int _samples, const float* _weights /*= 0*/ ) {
 
  MSTextureSampler& sampler = instance();
 
  // load shader
  if (!sampler.shaderNearest_)
    sampler.init();
 
  GLSL::Program* shader = sampler.shaderNearest_;
 
  if (!shader)
    return;
  
 
  shader->use();
 
  // offset and scale of screenquad
  shader->setUniform("offset", Vec2f(0.0f, 0.0f));
  shader->setUniform("size", Vec2f(1.0f, 1.0f));
  
  // sample count and filter weights
  shader->setUniform("numSamples", _samples);
 
  // bind multisampled texture to slot 0
  shader->setUniform("inputTex", 0);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, _texture);
 
  // run texture filter
  ScreenQuad::draw(shader);
 
  shader->disable();
}
 
//=============================================================================
 
void MSTextureSampler::filterMSAATexture_Nearest( GLuint _texture, GLuint _depthTexture, int _samples, const float* _weights /*= 0*/ ) {
 
  MSTextureSampler& sampler = instance();
 
  // load shader
  if (!sampler.shaderNearestDepth_)
    sampler.init();
 
//  GLSL::Program* shader = sampler.shaderNearestDepth_;
  GLSL::Program* shader = ACG::ShaderCache::getInstance()->getProgram(MSAA_SCREENQUAD_SHADER, MSAA_NEAREST_DEPTH_SHADER);
 
  if (!shader)
    return;
 
 
  shader->use();
 
  // offset and scale of screenquad
  shader->setUniform("offset", Vec2f(0.0f, 0.0f));
  shader->setUniform("size", Vec2f(1.0f, 1.0f));
 
  // sample count and filter weights
  shader->setUniform("numSamples", _samples);
 
  // bind multisampled depth texture to slot 1
  shader->setUniform("inputDepthTex", 1);
  glActiveTexture(GL_TEXTURE1);
  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, _depthTexture);
 
  // bind multisampled texture to slot 0
  shader->setUniform("inputTex", 0);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, _texture);
 
  // run texture filter
  ScreenQuad::draw(shader);
 
  shader->disable();
}
 
//=============================================================================
 
void MSTextureSampler::filterMSAATexture_Linear( GLuint _texture, int _samples, const float* _weights /*= 0*/ ) {
 
  MSTextureSampler& sampler = instance();
 
  // load shader
  if (!sampler.shaderLinear_)
    sampler.init();
 
  GLSL::Program* shader = sampler.shaderLinear_;
 
  if (!shader)
    return;
 
 
  shader->use();
 
  // offset and scale of screenquad
  shader->setUniform("offset", Vec2f(0.0f, 0.0f));
  shader->setUniform("size", Vec2f(1.0f, 1.0f));
 
  // sample count and filter weights
  shader->setUniform("numSamples", _samples);
 
  // bind multisampled texture to slot 0
  shader->setUniform("inputTex", 0);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, _texture);
 
  // run texture filter
  ScreenQuad::draw(shader);
 
  shader->disable();
}
 
 
//=============================================================================
 
 
 
#endif // MSTEXTURESAMPLER
 
 
} // namespace ACG
//=============================================================================