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glslinfinity

glsl infinity constant

Does GLSL have any pre-defined constants for +/-infinity or NaN? I'm doing this as a workaround but I wonder if there is a cleaner way:

// GLSL FRAGMENT SHADER
#version 410

<snip>

const float infinity = 1. / 0.;

void main ()
{
    <snip>
}

I am aware of the isinf function but I need to assign infinity to a variable so that does not help me.

Solution

  • Like Nicol mentioned, there are no pre-defined constants.

    However, from OpenGL 4.1 on, your solution is at least guaranteed to work and correctly generate an infinite value.

    See for example in glsl 4.4:

    4.7.1 Range and Precision

    ...

    However, dividing a non-zero by 0 results in the appropriately signed IEEE Inf: If both positive and negative zeros are implemented, the correctly signed Inf will be generated, otherwise positive Inf is generated.

    Be careful when you use an older version of OpenGL though:

    For example in glsl 4.0 it says:

    4.1.4 Floats

    ...

    Similarly, treatment of conditions such as divide by 0 may lead to an unspecified result, but in no case should such a condition lead to the interruption or termination of processing.