34 lines
941 B
GLSL
34 lines
941 B
GLSL
uniform sampler2D ove_maintex;
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uniform vec2 viewport;
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uniform float histogram_scale;
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in vec2 ove_texcoord;
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out vec4 fragColor;
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void main(void) {
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float histogram_width = ceil(histogram_scale * viewport.y);
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float quantisation = 1.0 / (histogram_width - 1.0);
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vec3 cur_col = vec3(0.0);
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vec3 sum = vec3(0.0);
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float ratio = 0.0;
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for (int i = 0; i < histogram_width; i++) {
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ratio = float(i) / float(histogram_width - 1);
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cur_col = texture(
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ove_maintex,
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vec2(ove_texcoord.y, ratio)
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).rgb;
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sum += step(vec3(ove_texcoord.x - quantisation), cur_col) *
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step(cur_col, vec3(ove_texcoord.x + quantisation)) +
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(
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// Account for values beyond the upper x limit.
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step(1.0 - quantisation, ove_texcoord.x) *
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step(vec3(1.0 - quantisation), cur_col)
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);
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}
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fragColor = vec4(sum, 1.0);
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}
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