Method GetShiftAndScale

Rendering/OpenGL2/vtkTextureObject.cxx:730–778

}

void vtkTextureObject::GetShiftAndScale(float& shift, float& scale)
{
  shift = 1.0;
  scale = 1.0;

  // check to see if this is an int format
  GLenum iresult = this->Context->GetDefaultTextureInternalFormat(
    vtkGetVTKType(this->Type), this->Components, true, false, this->UseSRGBColorSpace);

  // using an int texture format, no shift scale
  if (iresult == this->InternalFormat)
  {
    return;
  }

  // for all float type internal formats
  switch (this->Type)
  {
    case GL_BYTE:
      scale = (VTK_SIGNED_CHAR_MAX - VTK_SIGNED_CHAR_MIN) / 2.0;
      shift = scale + VTK_SIGNED_CHAR_MIN;
      break;
    case GL_UNSIGNED_BYTE:
      scale = VTK_UNSIGNED_CHAR_MAX;
      shift = 0.0;
      break;
    case GL_SHORT:
      // this may be off a tad
      scale = (VTK_SHORT_MAX - VTK_SHORT_MIN) / 2.0;
      shift = scale + VTK_SHORT_MIN;
      break;
    case GL_UNSIGNED_SHORT:
      scale = VTK_UNSIGNED_SHORT_MAX;
      shift = 0.0;
      break;
    case GL_INT:
      // this may be off a tad
      scale = (1.0 * VTK_INT_MAX - VTK_INT_MIN) / 2.0;
      shift = scale + VTK_INT_MIN;
      break;
    case GL_UNSIGNED_INT:
      scale = static_cast<float>(VTK_UNSIGNED_INT_MAX);
      shift = 0.0;
      break;
    case GL_FLOAT:
    default:
      break;
  }
}

//------------------------------------------------------------------------------
unsigned int vtkTextureObject::GetFormat(int vtktype, int numComps, bool shaderSupportsTextureInt)