iOS safari shader compilation issue (#471)

Co-authored-by: Ping Yu <[email protected]>

Author: jgreene

handpose/src/rotate_gpu.ts

@@ -57,10 +57,10 @@ export function rotate(
         ivec4 coords = getOutputCoords();
         int x = coords[2];
         int y = coords[1];
-        int coordX = int(float(x - ${centerX}) * ${cosFactor} -
-          float(y - ${centerY}) * ${sinFactor});
-        int coordY = int(float(x - ${centerX}) * ${sinFactor} +
-          float(y - ${centerY}) * ${cosFactor});
+        int coordX = int(float(x - ${centerX}) * float(${cosFactor}) -
+          float(y - ${centerY}) * float(${sinFactor}));
+        int coordY = int(float(x - ${centerX}) * float(${sinFactor}) +
+          float(y - ${centerY}) * float(${cosFactor}));
         coordX = int(coordX + ${centerX});
         coordY = int(coordY + ${centerY});