80 lines
2.1 KiB
GLSL
80 lines
2.1 KiB
GLSL
#version 330
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in vec2 fragWorldPos;
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out vec4 finalColor;
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uniform float time;
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#define TRAIL_POINTS 12
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uniform vec2 trailPoints[TRAIL_POINTS];
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uniform float trailAges[TRAIL_POINTS];
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uniform int trailCount;
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uniform float wakeIntensity;
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uniform vec4 foamColor = vec4(0.96, 0.99, 1.0, 1.0);
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uniform float wakeHalfWidthStart = 2.0;
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uniform float wakeHalfWidthEnd = 7.0;
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uniform float foamNoiseScale = 0.5;
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uniform float foamAnimSpeed = 2.4;
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float hash(vec2 p)
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{
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p = fract(p * vec2(123.34, 456.21));
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p += dot(p, p + 45.32);
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return fract(p.x * p.y);
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}
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float valueNoise(vec2 p)
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{
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vec2 i = floor(p);
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vec2 f = fract(p);
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float a = hash(i);
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float b = hash(i + vec2(1.0, 0.0));
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float c = hash(i + vec2(0.0, 1.0));
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float d = hash(i + vec2(1.0, 1.0));
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vec2 u = f * f * (3.0 - 2.0 * f);
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return mix(a, b, u.x) + (c - a) * u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
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}
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float segmentDistance(vec2 p, vec2 a, vec2 b, out float segT)
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{
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vec2 ab = b - a;
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float lenSq = dot(ab, ab);
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segT = lenSq > 0.0001 ? clamp(dot(p - a, ab) / lenSq, 0.0, 1.0) : 0.0;
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vec2 closest = a + ab * segT;
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return length(p - closest);
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}
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void main()
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{
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if (trailCount < 2) discard;
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float bestDist = 1e9;
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float bestAge = 0.0;
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for (int i = 0; i < TRAIL_POINTS - 1; i++) {
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if (i >= trailCount - 1) break;
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float segT;
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float d = segmentDistance(fragWorldPos, trailPoints[i], trailPoints[i + 1], segT);
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if (d < bestDist) {
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bestDist = d;
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bestAge = mix(trailAges[i], trailAges[i + 1], segT);
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}
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}
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float halfWidth = mix(wakeHalfWidthStart, wakeHalfWidthEnd, bestAge);
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if (bestDist > halfWidth) discard;
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float edgeFade = 1.0 - smoothstep(halfWidth * 0.55, halfWidth, bestDist);
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float ageFade = 1.0 - bestAge;
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float envelope = edgeFade * ageFade;
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vec2 pixelized = floor(fragWorldPos);
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float n = valueNoise(pixelized * foamNoiseScale + vec2(time * foamAnimSpeed, 0.0));
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float churn = mix(0.55, 1.0, n);
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float speedScale = mix(0.65, 1.0, wakeIntensity);
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float mask = envelope * churn * speedScale;
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finalColor = vec4(foamColor.rgb, foamColor.a * mask);
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}
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