With this function you can set the value (or values) of a shader constant. You must previously have gotten the "handle" of the constant using the function shader_get_uniform, and you will have to know what type of constant it is to pass the correct number of integer values through to it, ie: if you have a vec2 you will need to pass two values to the function.
shader_set_uniform_i(handle, value1 [, value2, value3, value4]);
|handle||The handle of the shader constant to set.|
|value1 ... value4||The integer value (or values) to set the shader constant to.|
shader_params = shader_get_uniform(shader_glass, "u_vParams");
shader_set_uniform_i(shader_params, 0, 65, 255);
The above code will get the handle of the shader constant "u_vParams" ( a vec3), then set that constant to the given integer values.