33 lines
1.1 KiB
GLSL
33 lines
1.1 KiB
GLSL
#version 330
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const int MAX_INDEXED_COLORS = 8;
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// Input fragment attributes (from fragment shader)
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in vec2 fragTexCoord;
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in vec4 fragColor;
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// Input uniform values
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uniform sampler2D texture0;
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uniform ivec3 palette[MAX_INDEXED_COLORS];
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//uniform sampler2D palette; // Alternative to ivec3, palette provided as a 256x1 texture
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// Output fragment color
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out vec4 finalColor;
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void main()
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{
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// Texel color fetching from texture sampler
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// NOTE: The texel is actually the a GRAYSCALE index color
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vec4 texelColor = texture(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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//finalColor = texture(palette, texelColor.xy); // Alternative to ivec3
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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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finalColor = vec4(color/255.0, texelColor.a);
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}
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