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Thread: Passing Colours Through Shaders

  1. #1
    Junior Member Newbie
    Join Date
    Mar 2014
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    4

    Passing Colours Through Shaders

    Hello guys,

    I've just started learning OpenGL and need some help with passing through colours. When I had just a vertex and fragment shader, I could pass colours through simply. Then I added tessellation control and tessellation evaluation shaders, and am not sure how to pass them through. My ultimate goal is to apply lighting to a sphere, but right now I just need to get the colours working.

    In my vertex shader, I have this declared:
    layout (location=2) in vec3 colour;
    out vec3 v_colour;

    In my fragment shader:
    in vec3 v_colour;
    out vec4 colour;

    How can I pass it from the vertex shader through tessellation control and evaluation to the fragment shader?

    Thanks for any help.

    Mr_Bean

  2. #2
    Senior Member OpenGL Pro
    Join Date
    Jan 2012
    Location
    Australia
    Posts
    1,117
    Not a lot changes except the input is an array of all the patch vertices and you have to decide which input colour to use as an output for an output vertex - it may even be a computed colour

  3. #3
    Junior Member Newbie
    Join Date
    Mar 2014
    Posts
    4
    Thanks for the reply. I've managed to get the colours working.
    I have another problem now. I've added a geometry shader (to implement Flat Shading), but it complains that it can't find my uniform mat4s when using glGetUniformLocation (which are declared in the Tessellation Evaluation shader). How can I fix this?

    EDIT: Never mind, I had an empty main function in the GS. When I put pass-through code in, the problem was resolved.

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