Slight optimization and rescaling of 2D noise

benchmark/common/commonShader.frag

@@ -1,6 +1,6 @@
 VERSION
 
-// uniform vec4 pParam; 
+// uniform vec4 pParam;
 // Example constant with a 289-element permutation
 const vec4 pParam = vec4( 17.0*17.0, 34.0, 1.0, 7.0);
 
@@ -19,3 +19,4 @@ void main( void )
 
   gl_FragColor = vec4(0.5 + 0.5 * vec3(n, n, n), 1.0);
 }
+

src/noise2D.glsl

@@ -41,12 +41,11 @@ float simplexNoise(vec2 v)
 #ifndef USE_CIRCLE
 // ( N points uniformly over a line, mapped onto a diamond.)
   vec3 x = 2.0 * fract(p / pParam.w) - 1. ;
-  vec3 h = 0.5 - abs(x) ;
+  vec3 h = abs(x) - 0.5 ;
 
-  vec3 sx = 2.*floor(x) + 1.;
-  vec3 sh = floor(h);
+  vec3 ox = floor(x+0.5);
 
-  vec3 a0 = x + sx*sh;
+  vec3 a0 = x - ox;
 
 # ifdef NORMALISE_GRADIENTS
   m *= taylorInvSqrt( a0*a0 + h*h );
@@ -62,7 +61,7 @@ float simplexNoise(vec2 v)
   g.x  = a0.x  * x0.x  + h.x  * x0.y;
   g.yz = a0.yz * xC.xz + h.yz * xC.yw;
 
-  return 1.66666* 70. *2. * dot(m, g);
+  return 200.0 * dot(m, g);
 #else 
 // N points around a unit circle.
   vec3 phi = D.z * mod(p,pParam.w) /pParam.w ;
@@ -70,7 +69,6 @@ float simplexNoise(vec2 v)
   vec2 a1 = sin(phi.zz  +D.xy);
 // mix
   vec3 g = vec3( dot(a0.xy, x0), dot(a0.zw, xC.xy), dot(a1.xy, xC.zw) );
-  return 1.66666* 70.*dot(m, g);
+  return 200.0 * dot(m, g);
 #endif
   }
-

src/noise4D.glsl

@@ -92,7 +92,7 @@ float simplexNoise(vec4 v)
   vec2 m1 = max(0.6 - vec2(dot(x3,x3), dot(x4,x4)            ), 0.0);
   m0 = m0 * m0;
   m1 = m1 * m1;
-  return 32. * ( dot(m0*m0, vec3( dot( p0, x0 ), dot( p1, x1 ), dot( p2, x2 )))
+  return 44.0 * ( dot(m0*m0, vec3( dot( p0, x0 ), dot( p1, x1 ), dot( p2, x2 )))
                + dot(m1*m1, vec2( dot( p3, x3 ), dot( p4, x4 ) ) ) ) ;
 
   }