blender/intern/cycles/kernel/svm/svm_musgrave.h

/*
 * 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

/* Musgrave fBm
 *
 * H: fractal increment parameter
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 *
 * from "Texturing and Modelling: A procedural approach"
 */

ccl_device_noinline float noise_musgrave_fBm(float3 p, float H, float lacunarity, float octaves)
{
  float rmd;
  float value = 0.0f;
  float pwr = 1.0f;
  float pwHL = powf(lacunarity, -H);
  int i;

  for (i = 0; i < float_to_int(octaves); i++) {
    value += snoise(p) * pwr;
    pwr *= pwHL;
    p *= lacunarity;
  }

  rmd = octaves - floorf(octaves);
  if (rmd != 0.0f)
    value += rmd * snoise(p) * pwr;

  return value;
}

/* Musgrave Multifractal
 *
 * H: highest fractal dimension
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 */

ccl_device_noinline float noise_musgrave_multi_fractal(float3 p,
                                                       float H,
                                                       float lacunarity,
                                                       float octaves)
{
  float rmd;
  float value = 1.0f;
  float pwr = 1.0f;
  float pwHL = powf(lacunarity, -H);
  int i;

  for (i = 0; i < float_to_int(octaves); i++) {
    value *= (pwr * snoise(p) + 1.0f);
    pwr *= pwHL;
    p *= lacunarity;
  }

  rmd = octaves - floorf(octaves);
  if (rmd != 0.0f)
    value *= (rmd * pwr * snoise(p) + 1.0f); /* correct? */

  return value;
}

/* Musgrave Heterogeneous Terrain
 *
 * H: fractal dimension of the roughest area
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 * offset: raises the terrain from `sea level'
 */

ccl_device_noinline float noise_musgrave_hetero_terrain(
    float3 p, float H, float lacunarity, float octaves, float offset)
{
  float value, increment, rmd;
  float pwHL = powf(lacunarity, -H);
  float pwr = pwHL;
  int i;

  /* first unscaled octave of function; later octaves are scaled */
  value = offset + snoise(p);
  p *= lacunarity;

  for (i = 1; i < float_to_int(octaves); i++) {
    increment = (snoise(p) + offset) * pwr * value;
    value += increment;
    pwr *= pwHL;
    p *= lacunarity;
  }

  rmd = octaves - floorf(octaves);
  if (rmd != 0.0f) {
    increment = (snoise(p) + offset) * pwr * value;
    value += rmd * increment;
  }

  return value;
}

/* Hybrid Additive/Multiplicative Multifractal Terrain
 *
 * H: fractal dimension of the roughest area
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 * offset: raises the terrain from `sea level'
 */

ccl_device_noinline float noise_musgrave_hybrid_multi_fractal(
    float3 p, float H, float lacunarity, float octaves, float offset, float gain)
{
  float result, signal, weight, rmd;
  float pwHL = powf(lacunarity, -H);
  float pwr = pwHL;
  int i;

  result = snoise(p) + offset;
  weight = gain * result;
  p *= lacunarity;

  for (i = 1; (weight > 0.001f) && (i < float_to_int(octaves)); i++) {
    if (weight > 1.0f)
      weight = 1.0f;

    signal = (snoise(p) + offset) * pwr;
    pwr *= pwHL;
    result += weight * signal;
    weight *= gain * signal;
    p *= lacunarity;
  }

  rmd = octaves - floorf(octaves);
  if (rmd != 0.0f)
    result += rmd * ((snoise(p) + offset) * pwr);

  return result;
}

/* Ridged Multifractal Terrain
 *
 * H: fractal dimension of the roughest area
 * lacunarity: gap between successive frequencies
 * octaves: number of frequencies in the fBm
 * offset: raises the terrain from `sea level'
 */

ccl_device_noinline float noise_musgrave_ridged_multi_fractal(
    float3 p, float H, float lacunarity, float octaves, float offset, float gain)
{
  float result, signal, weight;
  float pwHL = powf(lacunarity, -H);
  float pwr = pwHL;
  int i;

  signal = offset - fabsf(snoise(p));
  signal *= signal;
  result = signal;
  weight = 1.0f;

  for (i = 1; i < float_to_int(octaves); i++) {
    p *= lacunarity;
    weight = saturate(signal * gain);
    signal = offset - fabsf(snoise(p));
    signal *= signal;
    signal *= weight;
    result += signal * pwr;
    pwr *= pwHL;
  }

  return result;
}

/* Shader */

ccl_device float svm_musgrave(NodeMusgraveType type,
                              float dimension,
                              float lacunarity,
                              float octaves,
                              float offset,
                              float intensity,
                              float gain,
                              float3 p)
{
  if (type == NODE_MUSGRAVE_MULTIFRACTAL)
    return intensity * noise_musgrave_multi_fractal(p, dimension, lacunarity, octaves);
  else if (type == NODE_MUSGRAVE_FBM)
    return intensity * noise_musgrave_fBm(p, dimension, lacunarity, octaves);
  else if (type == NODE_MUSGRAVE_HYBRID_MULTIFRACTAL)
    return intensity *
           noise_musgrave_hybrid_multi_fractal(p, dimension, lacunarity, octaves, offset, gain);
  else if (type == NODE_MUSGRAVE_RIDGED_MULTIFRACTAL)
    return intensity *
           noise_musgrave_ridged_multi_fractal(p, dimension, lacunarity, octaves, offset, gain);
  else if (type == NODE_MUSGRAVE_HETERO_TERRAIN)
    return intensity * noise_musgrave_hetero_terrain(p, dimension, lacunarity, octaves, offset);

  return 0.0f;
}

ccl_device void svm_node_tex_musgrave(
    KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
{
  uint4 node2 = read_node(kg, offset);
  uint4 node3 = read_node(kg, offset);

  uint type, co_offset, color_offset, fac_offset;
  uint dimension_offset, lacunarity_offset, detail_offset, offset_offset;
  uint gain_offset, scale_offset;

  decode_node_uchar4(node.y, &type, &co_offset, &color_offset, &fac_offset);
  decode_node_uchar4(
      node.z, &dimension_offset, &lacunarity_offset, &detail_offset, &offset_offset);
  decode_node_uchar4(node.w, &gain_offset, &scale_offset, NULL, NULL);

  float3 co = stack_load_float3(stack, co_offset);
  float dimension = stack_load_float_default(stack, dimension_offset, node2.x);
  float lacunarity = stack_load_float_default(stack, lacunarity_offset, node2.y);
  float detail = stack_load_float_default(stack, detail_offset, node2.z);
  float foffset = stack_load_float_default(stack, offset_offset, node2.w);
  float gain = stack_load_float_default(stack, gain_offset, node3.x);
  float scale = stack_load_float_default(stack, scale_offset, node3.y);

  dimension = fmaxf(dimension, 1e-5f);
  detail = clamp(detail, 0.0f, 16.0f);
  lacunarity = fmaxf(lacunarity, 1e-5f);

  float f = svm_musgrave(
      (NodeMusgraveType)type, dimension, lacunarity, detail, foffset, 1.0f, gain, co * scale);

  if (stack_valid(fac_offset))
    stack_store_float(stack, fac_offset, f);
  if (stack_valid(color_offset))
    stack_store_float3(stack, color_offset, make_float3(f, f, f));
}

CCL_NAMESPACE_END