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Asked: 2026-06-01T19:27:15+00:00

So I’m trying to replace a part of a texture over another in GLSL,

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So I’m trying to replace a part of a texture over another in GLSL, first step in a grand scheme.
So I have a image, 2048×2048, with 3 textures on the top left, each 512×512. For testing purposes I’m trying to just repeatedly draw the first one.

//get coord of smaller texture
coord = vec2(int(gl_TexCoord[0].s)%512,int(gl_TexCoord[0].t)%512);

//grab color from it and return it 
fragment = texture2D(textures, coord);
gl_FragColor = fragment;

It seems that it only grabs the same pixel, I get one color from the texture returned to me. Everything ends up grey. Anyone know what’s off?

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1 Answer

  1. Editorial Team

    Unless that’s a rectangle texture (which is isn’t since you’re using texture2D), your texture coordinates are normalized. That means that the range [0, 1] maps to the entire range of the texture. 0.5 always means halfway, whether for a 256 sized texture or a 8192 one.

    Therefore, you need to stop passing non-normalized texture coordinates (texel values). Pass normalized texture coordinates and adjust those.

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