/**
|
* @private
|
*/
|
vec4 czm_getWaterNoise(sampler2D normalMap, vec2 uv, float time, float angleInRadians)
|
{
|
float cosAngle = cos(angleInRadians);
|
float sinAngle = sin(angleInRadians);
|
|
// time dependent sampling directions
|
vec2 s0 = vec2(1.0/17.0, 0.0);
|
vec2 s1 = vec2(-1.0/29.0, 0.0);
|
vec2 s2 = vec2(1.0/101.0, 1.0/59.0);
|
vec2 s3 = vec2(-1.0/109.0, -1.0/57.0);
|
|
// rotate sampling direction by specified angle
|
s0 = vec2((cosAngle * s0.x) - (sinAngle * s0.y), (sinAngle * s0.x) + (cosAngle * s0.y));
|
s1 = vec2((cosAngle * s1.x) - (sinAngle * s1.y), (sinAngle * s1.x) + (cosAngle * s1.y));
|
s2 = vec2((cosAngle * s2.x) - (sinAngle * s2.y), (sinAngle * s2.x) + (cosAngle * s2.y));
|
s3 = vec2((cosAngle * s3.x) - (sinAngle * s3.y), (sinAngle * s3.x) + (cosAngle * s3.y));
|
|
vec2 uv0 = (uv/103.0) + (time * s0);
|
vec2 uv1 = uv/107.0 + (time * s1) + vec2(0.23);
|
vec2 uv2 = uv/vec2(897.0, 983.0) + (time * s2) + vec2(0.51);
|
vec2 uv3 = uv/vec2(991.0, 877.0) + (time * s3) + vec2(0.71);
|
|
uv0 = fract(uv0);
|
uv1 = fract(uv1);
|
uv2 = fract(uv2);
|
uv3 = fract(uv3);
|
vec4 noise = (texture2D(normalMap, uv0)) +
|
(texture2D(normalMap, uv1)) +
|
(texture2D(normalMap, uv2)) +
|
(texture2D(normalMap, uv3));
|
|
// average and scale to between -1 and 1
|
return ((noise / 4.0) - 0.5) * 2.0;
|
}
|
