GLSL Shader Actor - mat2 input

  • Dear All,

    A user sent me a GLSL Shader actor that wasn't working.... the code that caused it to fail is below.

    // ISADORA_FLOAT_PARAM(complexity, complex, 9.0, 900.0, 10.0, "veraendere dichtheit");

    uniform mat2 complexity;

    Note that while they have specified a floating point input, the actual uniform variable declared by complexity is a **mat2** – that's not a single float, but actually four floats! (You can learn more about GLSL types [on this page](
    To provide like input to a **mat2**, you'd need to define four separate inputs

    // ISADORA_FLOAT_PARAM(complexity00, cp00, 9.0, 900.0, 10.0, "veraendere dichtheit");

    // ISADORA_FLOAT_PARAM(complexity01, cp01, 9.0, 900.0, 10.0, "veraendere dichtheit");

    // ISADORA_FLOAT_PARAM(complexity10, cp10, 9.0, 900.0, 10.0, "veraendere dichtheit");

    // ISADORA_FLOAT_PARAM(complexity11, cp11, 9.0, 900.0, 10.0, "veraendere dichtheit");

    uniform float complexity00;

    uniform float complexity01;

    uniform float complexity10;

    uniform float complexity11;

    and then somewhere within your code, you'd need this to initialize a **mat2**called complexity as follows:

    mat2 complexity;

    complexity[0][0] = complexity00;

    complexity[0][1] = complexity01;

    complexity[1][0] = complexity10;

    complexity[1][1] = complexity11;


    I tested this and it works. Hopefully that will help one of you down the road.


    Best Wishes,


  • nice

  • Tech Staff

    This should be added to a Knowledge base article on GLSL usage.

  • Dear @DusX,

    Added the mat2 stuff to the tutorial as an addendum.

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