Optimize sqrt calls (#8070)

Author: willeastcott

src/core/math/random.js

@@ -36,7 +36,7 @@ const random = {
      */
     circlePointDeterministic(point, index, numPoints) {
         const theta = index * _goldenAngle;
-        const r = Math.sqrt(index) / Math.sqrt(numPoints);
+        const r = Math.sqrt(index / numPoints);
 
         point.x = r * Math.cos(theta);
         point.y = r * Math.sin(theta);

src/scene/gsplat/gsplat-compressed-data.js

@@ -32,7 +32,7 @@ class SplatCompressedIterator {
 
         // unpack quaternion with 2,10,10,10 format (largest element, 3x10bit element)
         const unpackRot = (result, value) => {
-            const norm = 1.0 / (Math.sqrt(2) * 0.5);
+            const norm = Math.SQRT2;
             const a = (unpackUnorm(value >>> 20, 10) - 0.5) * norm;
             const b = (unpackUnorm(value >>> 10, 10) - 0.5) * norm;
             const c = (unpackUnorm(value, 10) - 0.5) * norm;

src/scene/gsplat/gsplat-sogs-data.js

@@ -54,7 +54,7 @@ class GSplatSogsIterator {
         const sh_labels_data = sh && data.sh_labels._levels[0];
         const sh_centroids_data = sh && data.sh_centroids._levels[0];
 
-        const norm = 2.0 / Math.sqrt(2.0);
+        const norm = Math.SQRT2;
 
         const coeffs = { 1: 3, 2: 8, 3: 15 }[shBands] ?? 0;
 

src/scene/shader-lib/glsl/chunks/gsplat/vert/gsplatCompressedData.js

@@ -27,7 +27,7 @@ vec4 unpack8888(uint bits) {
     );
 }
 
-const float norm = 1.0 / (sqrt(2.0) * 0.5);
+const float norm = sqrt(2.0);
 
 vec4 unpackRotation(uint bits) {
     float a = (float((bits >> 20u) & 0x3ffu) / 1023.0 - 0.5) * norm;

src/scene/shader-lib/glsl/chunks/gsplat/vert/gsplatSogsData.js

@@ -25,7 +25,7 @@ vec3 readCenter(SplatSource source) {
     return sign(v) * (exp(abs(v)) - 1.0);
 }
 
-const float norm = 2.0 / sqrt(2.0);
+const float norm = sqrt(2.0);
 
 // sample covariance vectors
 void readCovariance(in SplatSource source, out vec3 covA, out vec3 covB) {

src/scene/shader-lib/wgsl/chunks/gsplat/vert/gsplatCompressedData.js

@@ -23,7 +23,7 @@ fn unpack8888(bits: u32) -> vec4f {
     ) / 255.0;
 }
 
-const norm_const: f32 = 1.0 / (sqrt(2.0) * 0.5);
+const norm_const: f32 = sqrt(2.0);
 
 fn unpackRotation(bits: u32) -> vec4f {
     let a = (f32((bits >> 20u) & 0x3ffu) / 1023.0 - 0.5) * norm_const;

src/scene/shader-lib/wgsl/chunks/gsplat/vert/gsplatSogsData.js

@@ -24,7 +24,7 @@ fn readCenter(source: ptr<function, SplatSource>) -> vec3f {
     return sign(v) * (exp(abs(v)) - 1.0);
 }
 
-const norm: f32 = 2.0 / sqrt(2.0);
+const norm: f32 = sqrt(2.0);
 
 // sample covariance vectors
 fn readCovariance(source: ptr<function, SplatSource>, covA_ptr: ptr<function, vec3f>, covB_ptr: ptr<function, vec3f>) {