   Gaussian Convolution in GLSL
  Hi there , I'm trying to do 2D Gaussian convolution via two 1D convolutions based on the seperability of the Gaussian Filter.The first pass (row-wise 1D convolution) can easily be done as the input is a texture , and it is very easy to adress each texel using texture coordinates and offsets. However I'm having trouble with the second pass (column-wise 1D convolution) because I cannot adress each pixel from the output of the first pass. How can this be done? The procedure is like this:Input : Texture -> 1D row-wise Convolution -> Output: Variable -> 1D column-wise Convolution -> Output:FrameBufferAs you can see , the trouble is in going from step 3 to step 4 , as the input for the second convolution is an intermediate variable and not a texture. Any ideas?   
  the traditional method is to do two passes and do a render-to-texture from the first pass and use it as input to the 2nd pass.texture => 1D row-wise Convolution => FBO/texturetexture => 1D column-wise Convolution  => FBO/texture/framebuffer depending on if you want more stages   