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Modify a texture within a shader?

edited March 2013 in Shaders Posts: 24

Hi,

I would like to store information computed by a shader in a texture and keep modifiying the texture over time in the shader ( texture will store a progressive deformation of the screen). Is it possible? Can you give me a quick sample?

Thanks for your help and many thanks to the Codea team for this great app!

Comments

  • Posts: 455

    This is doable, theres an example in http://twolivesleft.com/Codea/Talk/discussion/2252/game-of-life-shader

    Basically, you can't modify the texture directly, but you can setContext() to an image, then render your mesh in that context, then attach that as a texture to another mesh/shader etc...

    This is my next project when I get time to try and do multipass for shadow mapping...

    Conceptually it's a bit like the following psuedo code, assume the meshes exist and have useful/sensible shaders

    setup()
       pass1Texture = image(500,500)
    
    draw()
       setContext(pass1Texture)
       mesh1:draw()
    
       --revert to normal context
       setContext()
       mesh2.texture = pass1Texture
       mesh2:draw()
    
  • Posts: 24

    Thanks, I will give a try.

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