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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
CCL_NAMESPACE_BEGIN
/* Turbulence */
ccl_device_noinline float noise_turbulence(float3 p, float octaves, int hard)
{
float fscale = 1.0f;
float amp = 1.0f;
float sum = 0.0f;
int i, n;
octaves = clamp(octaves, 0.0f, 16.0f);
n = float_to_int(octaves);
for(i = 0; i <= n; i++) {
float t = noise(fscale*p);
if(hard)
t = fabsf(2.0f*t - 1.0f);
sum += t*amp;
amp *= 0.5f;
fscale *= 2.0f;
}
float rmd = octaves - floorf(octaves);
if(rmd != 0.0f) {
float t = noise(fscale*p);
if(hard)
t = fabsf(2.0f*t - 1.0f);
float sum2 = sum + t*amp;
sum *= ((float)(1 << n)/(float)((1 << (n+1)) - 1));
sum2 *= ((float)(1 << (n+1))/(float)((1 << (n+2)) - 1));
return (1.0f - rmd)*sum + rmd*sum2;
}
else {
sum *= ((float)(1 << n)/(float)((1 << (n+1)) - 1));
return sum;
}
}
CCL_NAMESPACE_END
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