mirror of
https://github.com/kovidgoyal/kitty
synced 2026-07-17 22:14:53 +02:00
83 lines
2.0 KiB
GLSL
83 lines
2.0 KiB
GLSL
#version 140
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#line 0 7893004
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vec4 alpha_blend(vec4 over, vec4 under) {
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// Alpha blend two colors returning the resulting color pre-multiplied by its alpha
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// and its alpha.
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// See https://en.wikipedia.org/wiki/Alpha_compositing
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float alpha = mix(under.a, 1.0f, over.a);
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vec3 combined_color = mix(under.rgb * under.a, over.rgb, over.a);
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return vec4(combined_color, alpha);
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}
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vec4 alpha_blend_premul(vec4 over, vec4 under) {
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// Same as alpha_blend() except that it assumes over and under are both premultiplied.
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float inv_over_alpha = 1.0f - over.a;
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float alpha = over.a + under.a * inv_over_alpha;
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return vec4(over.rgb + under.rgb * inv_over_alpha, alpha);
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}
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vec4 alpha_blend_premul(vec4 over, vec3 under) {
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// same as alpha_blend_premul with under_alpha = 1 outputs a blended color
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// with alpha 1 which is effectively pre-multiplied since alpha is 1
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float inv_over_alpha = 1.0f - over.a;
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return vec4(over.rgb + under.rgb * inv_over_alpha, 1.0);
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}
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#line 0 7893003
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#line 0 7893005
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// Return 0 if x < 1 otherwise 1
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#define zero_or_one(x) step(1.f, x)
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// condition must be zero or one. When 1 thenval is returned otherwise elseval
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#define if_one_then(condition, thenval, elseval) mix(elseval, thenval, condition)
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// a < b ? thenval : elseval
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#define if_less_than(a, b, thenval, elseval) mix(thenval, elseval, step(b, a))
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vec4 vec4_premul(vec3 rgb, float a) {
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return vec4(rgb * a, a);
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}
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vec4 vec4_premul(vec4 rgba) {
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return vec4(rgba.rgb * rgba.a, rgba.a);
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}
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#line 1 7893003
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#define IMAGE
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uniform sampler2D image;
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#ifdef ALPHA_MASK
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uniform vec3 amask_fg;
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uniform vec4 amask_bg_premult;
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#else
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uniform float extra_alpha;
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#endif
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in vec2 texcoord;
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out vec4 output_color;
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void main() {
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vec4 color = texture(image, texcoord);
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#ifdef ALPHA_MASK
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color = vec4(amask_fg, color.r);
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color = vec4_premul(color);
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color = alpha_blend_premul(color, amask_bg_premult);
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#else
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color.a *= extra_alpha;
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#if 0
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color = vec4_premul(color);
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#endif
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#endif
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output_color = color;
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}
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