Merge pull request #24 from shuding/shu/a3b6

Fix Android 12 support

Author: shuding

.gitignore

@@ -1,2 +1,3 @@
 dist
-node_modules
+node_modules
+.DS_Store

package.json

@@ -1,6 +1,6 @@
 {
   "name": "cobe",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "type": "module",
   "main": "./dist/index.esm.js",
   "files": [

src/shader.frag

@@ -77,9 +77,39 @@ vec3 nearestFibonacciLattice(vec3 p, out float m) {
     // float v = idx / kPhi;
     // float theta = fract(v) * kTau;
 
-    int iFracV = int(idx) * 2654435769; // signed be like nearest-to-zero fmod; 2^32/phi
-    float fracV = float(iFracV) * by2P32;
-    float theta = fracV * kTau;
+    // int iFracV = int(idx) * 2654435769; // signed be like nearest-to-zero fmod; 2^32/phi
+    // float fracV = float(iFracV) * by2P32;
+    // float theta = fracV * kTau;
+
+    // https://github.com/shuding/cobe/issues/16
+    
+    float tidx = idx;
+    float fracV = 0.;
+
+    // see codegen
+
+    if(tidx >= 524288.) { tidx-=524288.; fracV += 0.8038937048986554; }
+    if(tidx >= 262144.) { tidx-=262144.; fracV += 0.9019468524493277; }
+    if(tidx >= 131072.) { tidx-=131072.; fracV += 0.9509734262246639; }
+    if(tidx >= 65536.) { tidx-=65536.; fracV += 0.4754867131123319; }
+    if(tidx >= 32768.) { tidx-=32768.; fracV += 0.737743356556166; }
+    if(tidx >= 16384.) { tidx-=16384.; fracV += 0.868871678278083; }
+    if(tidx >= 8192.) { tidx-=8192.; fracV += 0.9344358391390415; }
+    if(tidx >= 4096.) { tidx-=4096.; fracV += 0.46721791956952075; }
+    if(tidx >= 2048.) { tidx-=2048.; fracV += 0.7336089597847604; }
+    if(tidx >= 1024.) { tidx-=1024.; fracV += 0.8668044798923802; }
+    if(tidx >= 512.) { tidx-=512.; fracV += 0.4334022399461901; }
+    if(tidx >= 256.) { tidx-=256.; fracV += 0.21670111997309505; }
+    if(tidx >= 128.) { tidx-=128.; fracV += 0.10835055998654752; }
+    if(tidx >= 64.) { tidx-=64.; fracV += 0.5541752799932738; }
+    if(tidx >= 32.) { tidx-=32.; fracV += 0.7770876399966369; }
+    if(tidx >= 16.) { tidx-=16.; fracV += 0.8885438199983184; }
+    if(tidx >= 8.) { tidx-=8.; fracV += 0.9442719099991592; }
+    if(tidx >= 4.) { tidx-=4.; fracV += 0.4721359549995796; }
+    if(tidx >= 2.) { tidx-=2.; fracV += 0.2360679774997898; }
+    if(tidx >= 1.) { tidx-=1.; fracV += 0.6180339887498949; }
+
+    float theta = fract(fracV) * kTau;
 
     float cosphi = 1. - 2. * idx * byDots;
     float sinphi = sqrt(1. - cosphi * cosphi);