Fixed glsl warning.

examples/webgl_gpgpu_birds.html

@@ -138,7 +138,7 @@
 			// const float VISION = PI * 0.55;
 
 			float zoneRadius = 40.0;
-			float zoneRadiusSquared = zoneRadius * zoneRadius;
+			float zoneRadiusSquared = 1600.0;
 
 			float separationThresh = 0.45;
 			float alignmentThresh = 0.65;