Merge pull request #228 from Fonger/perf/ts

(TypeScript) Improve decode speed by avoiding re-calculating same cosine value
woltapp · Mar 30, 2023 · f1edb10 · f1edb10
2 parents 065b960 + c747c91
commit f1edb10
Showing 1 changed file with 3 additions and 4 deletions.
diff --git a/TypeScript/src/decode.ts b/TypeScript/src/decode.ts
@@ -98,11 +98,10 @@ const decode = (
       let b = 0;
 
       for (let j = 0; j < numY; j++) {
+        const basisY = Math.cos((Math.PI * y * j) / height);
         for (let i = 0; i < numX; i++) {
-          const basis =
-            Math.cos((Math.PI * x * i) / width) *
-            Math.cos((Math.PI * y * j) / height);
-          let color = colors[i + j * numX];
+          const basis = Math.cos((Math.PI * x * i) / width) * basisY;
+          const color = colors[i + j * numX];
           r += color[0] * basis;
           g += color[1] * basis;
           b += color[2] * basis;