29 lines
842 B
GLSL
29 lines
842 B
GLSL
#version 100
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precision mediump float;
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const int colors = 8;
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// Input vertex attributes (from vertex shader)
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varying vec2 fragTexCoord;
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varying vec4 fragColor;
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// Input uniform values
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uniform sampler2D texture0;
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uniform ivec3 palette[colors];
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void main()
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{
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// Texel color fetching from texture sampler
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vec4 texelColor = texture2D(texture0, fragTexCoord) * fragColor;
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// Convert the (normalized) texel color RED component (GB would work, too)
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// to the palette index by scaling up from [0, 1] to [0, 255].
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int index = int(texelColor.r * 255.0);
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ivec3 color = palette[index];
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// Calculate final fragment color. Note that the palette color components
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// are defined in the range [0, 255] and need to be normalized to [0, 1]
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// for OpenGL to work.
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gl_FragColor = vec4(color / 255.0, texelColor.a);
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}
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