GLSL Shader Actor - mat2 input

[mark]

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](https://www.opengl.org/wiki/Data_Type_(GLSL)).)

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,

Mark

[fubbi]

nice

[DusX]

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

[mark]

Dear @DusX,

Added the mat2 stuff to the tutorial as an addendum.

Best,

Mark