Merge pull request #5491 from EVAST9919/blob-quick-fix

CircularBlob shader improvements

Author: peppy

osu.Framework/Resources/Shaders/sh_CircularBlobUtils.h

@@ -24,38 +24,37 @@ highp float noise(highp vec2 st)
 }
 
 lowp float blobAlphaAt(highp vec2 pixelPos, mediump float innerRadius, highp float texelSize, mediump float frequency, mediump float amplitude, int seed)
-{    
+{
     // Compute angle of the current pixel in the (0, 2*PI) range
     mediump float pixelAngle = atan(0.5 - pixelPos.y, 0.5 - pixelPos.x) - HALF_PI;
     if (pixelAngle < 0.0)
         pixelAngle += TWO_PI;
 
-    const int pointCount = 50;
+    mediump float complexity = (frequency + amplitude) * 0.5 + 1.0;
+
+    int pointCount = int(ceil(5.0 * complexity));
+    mediump float searchRange = 0.1 * complexity; // in radians
 
     mediump float pathRadius = innerRadius * 0.25;
 
     highp float shortestDistance = 1.0;
 
-    mediump float startAngle = pixelAngle - HALF_PI * 0.5 - HALF_PI;
+    mediump float startAngle = pixelAngle - searchRange * 0.5;
 
     // Looks to be random enough but still consistent
     highp vec2 noisePosition = vec2(random(vec2(float(seed) * 0.0001)) * 100000.0, random(vec2(float(seed) * 0.0001)) * 100000.0);
 
-    // Distance approximation
-    // Plot points within a search range (90 degrees seems enough) and check which one is closest
+    // Path approximation
+    // Plot points within a search range and check which one is closest
     for (int i = 0; i < pointCount; i++)
     {
-        mediump float angle = startAngle + HALF_PI * float(i) / float(pointCount);
-        highp vec2 cs = vec2(cos(angle), sin(angle));
+        mediump float angle = startAngle + searchRange * float(i) / float(pointCount);
+        highp vec2 cs = vec2(cos(angle - HALF_PI), sin(angle - HALF_PI));
 
         highp float noiseValue = noise(noisePosition + cs * vec2(frequency));
         highp vec2 pos = vec2(0.5) + cs * vec2(0.5 - pathRadius - texelSize - noiseValue * 0.5 * amplitude);
 
         shortestDistance = min(shortestDistance, distance(pixelPos, pos));
-
-        // No need to loop further if already inside the shape
-        if (shortestDistance < pathRadius)
-            break;
     }
 
     return smoothstep(texelSize, 0.0, shortestDistance - pathRadius);