Strange if-else branching behavior in a fragment shader

Posted by Winged on Game Development See other posts from Game Development or by Winged
Published on 2014-06-04T11:03:23Z Indexed on 2014/06/04 15:46 UTC
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glsl

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fragment-shader

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webgl

In my fragment shader I have passed an uniform int uLightType variable, which indicates what type of light is in usage right now. The problem is that if-else branching does not work correctly - the fragment shader performs instructions in every if statement block.

if (uLightType == 1) { // Spotlight light type
    vec3 depthTextureCoord = vDepthPosition.xyz / vDepthPosition.w;
    shadowDepth = unpack(texture2D(uDepthMapSampler, depthTextureCoord.xy));
}
else if (uLightType == 2) { // Omni-directional light type
    shadowDepth = unpack(textureCube(uDepthCubemapSampler, -lightVec));
}

In the case when uLightType equals 1, unless I comment out the content of the second if block, it assigns an another value to shadowDepth.

Also while uLightType equals 1, when I remove the second 'if' block and change == to != like in the sample code below, nothing happens (which means that uLightType really equals 1).

if (uLightType != 1) { // Spotlight light type
    vec3 depthTextureCoord = vDepthPosition.xyz / vDepthPosition.w;
    shadowDepth = unpack(texture2D(uDepthMapSampler, depthTextureCoord.xy));
}

Also, when I manually create an int variable (which is not an uniform) like this: var lightType = 1; and replace uLightType with it in the if-else branch, everything works fine, so I guess it have something to do with the fact that uLightType is the uniform.

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