mirror of
https://github.com/kovidgoyal/kitty
synced 2026-07-15 04:54:14 +02:00
95 lines
3.0 KiB
GLSL
95 lines
3.0 KiB
GLSL
#version 140
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#line 0 7893003
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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 7893002
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#line 0 7893004
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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 7893002
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in vec2 dimensions;
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out vec4 output_color;
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uniform vec4 rect;
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uniform vec2 params;
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uniform vec4 color;
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uniform vec4 background_color;
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// Signed distance function for a rounded rectangle
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float rounded_rectangle_sdf(vec2 p, vec2 b, float r) {
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// signed distance field
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// first term is used for points outside the rectangle
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vec2 q = abs(p) - b;
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return length(max(q, 0.0)) + min(max(q.x, q.y), 0.0) - r;
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}
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void main() {
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vec2 size = rect.ba, origin = rect.xy;
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float thickness = params[0], corner_radius = params[1];
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// Position must be relative to the center of the rectangle of (size) located at (origin)
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vec2 position = gl_FragCoord.xy - size / 2.0 - origin;
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// Calculate distance to rounded rectangle
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float dist = rounded_rectangle_sdf(position, size*0.5 - corner_radius, corner_radius);
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// The below is for a filled rounded rect
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// float alpha = 1.0 - smoothstep(0.0, 1.0, dist);
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// vec4 ans = color; ans.a *= alpha;
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// output_color = alpha_blend(ans, background_color);
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// The border is outer - inner rects
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float outer_edge = -dist, inner_edge = outer_edge - thickness;
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// Smooth borders (anti-alias)
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const float step_size = 1.0; // controls how blurred the aliasing causes the rect to be
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float alpha = smoothstep(-step_size, step_size, outer_edge) - smoothstep(-step_size, step_size, inner_edge);
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vec4 ans = color; ans.a *= alpha;
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// pre-multiplied output
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output_color = alpha_blend(ans, background_color);
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}
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