Which will be faster? Switching shaders or ignore that some cases don't need full code?

Posted by PolGraphic on Game Development See other posts from Game Development or by PolGraphic
Published on 2012-12-13T05:24:23Z Indexed on 2012/12/13 11:22 UTC
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I have two types of 2d objects:

In first case (for about 70% of objects), I need that code in the shader:

float2 texCoord = input.TexCoord + textureCoord.xy

But in the second case I have to use:

float2 texCoord = fmod(input.TexCoord, texCoordM.xy - textureCoord.xy) + textureCoord.xy

I can use second code also for first case, but it will be a little slower (fmod is useless here, input.TexCoord will be always lower than textureCoord.xy - textureCoord.xy for sure).

My question is, which way will be faster:

  1. Making two independent shaders for both types of rectangles, group rectangles by types and switch shaders during rendering.
  2. Make one shader and use some if statement.
  3. Make one shader and ignore that sometimes (70% of cases) I don't need to use fmod.

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