94 lines
2.9 KiB
GLSL
Executable File
94 lines
2.9 KiB
GLSL
Executable File
#version 440
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layout(location = 0) in vec2 qt_TexCoord0;
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layout(location = 0) out vec4 fragColor;
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// NOTE: std140 layout. Order/types must match the ShaderEffect properties by name.
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layout(std140, binding = 0) uniform buf {
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mat4 qt_Matrix;
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float qt_Opacity;
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vec2 itemSize; // full ShaderEffect size in px (rect + glow padding)
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vec2 rectSize; // size of the target rectangle in px
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float radius; // corner radius of the target rectangle in px
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float glowSize; // how far the glow extends outside the rectangle (px)
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float innerGlow; // how far the glow bleeds inside (px), 0 = none
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float lineWidth; // width of the bright edge line (px), 0 = none
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float phase; // 0..1, loops seamlessly
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float intensity; // overall brightness
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vec4 color1;
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vec4 color2;
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vec4 color3;
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vec4 color4;
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};
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const float TAU = 6.28318530718;
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// Signed distance to a rounded box centred at the origin. <0 inside, >0 outside.
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float sdRoundBox(vec2 p, vec2 halfSize, float r)
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{
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vec2 q = abs(p) - (halfSize - r);
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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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// Cyclic 4-colour gradient, t is wrapped to [0,1)
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vec3 palette(float t)
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{
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t = fract(t) * 4.0;
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float f = smoothstep(0.0, 1.0, fract(t));
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if (t < 1.0) return mix(color1.rgb, color2.rgb, f);
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if (t < 2.0) return mix(color2.rgb, color3.rgb, f);
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if (t < 3.0) return mix(color3.rgb, color4.rgb, f);
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return mix(color4.rgb, color1.rgb, f);
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}
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// Cheap hash for dithering (avoids banding in soft gradients)
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float hash(vec2 p)
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{
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return fract(sin(dot(p, vec2(12.9898, 78.233))) * 43758.5453);
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}
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void main()
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{
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// Pixel position relative to the centre of the item
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vec2 p = (qt_TexCoord0 - 0.5) * itemSize;
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float r = clamp(radius, 0.0, min(rectSize.x, rectSize.y) * 0.5);
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float d = sdRoundBox(p, rectSize * 0.5, r);
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// ---- colour: rotates around the rectangle, slightly wobbling ----
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float ang = atan(p.y, p.x);
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float a2 = phase * TAU;
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float u = ang / TAU + 0.5 + phase;
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u += 0.07 * sin(ang * 2.0 + a2) + 0.04 * sin(ang * 3.0 - a2 * 2.0);
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vec3 col = palette(u);
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// ---- intensity falloff ----
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float g = 0.0;
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if (d > 0.0) {
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float t = clamp(d / max(glowSize, 0.001), 0.0, 1.0);
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g = pow(1.0 - t, 3.0);
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} else if (innerGlow > 0.0) {
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g = exp(d / innerGlow * 3.0);
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}
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// Slow "breathing" so the glow feels alive
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float pulse = 0.9 + 0.1 * sin(a2 * 2.0 + ang);
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g *= pulse;
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// Crisp bright line along the edge
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float line = 0.0;
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if (lineWidth > 0.0)
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line = 1.0 - smoothstep(0.0, lineWidth, abs(d));
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float a = clamp(g * intensity + line * 0.9, 0.0, 1.0);
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// Brighten the colour a bit where the line is
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col = mix(col, vec3(1.0), line * 0.25);
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a += (hash(gl_FragCoord.xy) - 0.5) / 255.0;
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a = clamp(a, 0.0, 1.0);
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// Premultiplied alpha output
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fragColor = vec4(col * a, a) * qt_Opacity;
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}
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