blender/intern/cycles/kernel/svm/svm_ramp.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.
 */

#ifndef __SVM_RAMP_H__
#define __SVM_RAMP_H__

CCL_NAMESPACE_BEGIN

/* NOTE: svm_ramp.h, svm_ramp_util.h and node_ramp_util.h must stay consistent */

ccl_device_inline float4 rgb_ramp_lookup(
    KernelGlobals *kg, int offset, float f, bool interpolate, bool extrapolate, int table_size)
{
  if ((f < 0.0f || f > 1.0f) && extrapolate) {
    float4 t0, dy;
    if (f < 0.0f) {
      t0 = fetch_node_float(kg, offset);
      dy = t0 - fetch_node_float(kg, offset + 1);
      f = -f;
    }
    else {
      t0 = fetch_node_float(kg, offset + table_size - 1);
      dy = t0 - fetch_node_float(kg, offset + table_size - 2);
      f = f - 1.0f;
    }
    return t0 + dy * f * (table_size - 1);
  }

  f = saturate(f) * (table_size - 1);

  /* clamp int as well in case of NaN */
  int i = clamp(float_to_int(f), 0, table_size - 1);
  float t = f - (float)i;

  float4 a = fetch_node_float(kg, offset + i);

  if (interpolate && t > 0.0f)
    a = (1.0f - t) * a + t * fetch_node_float(kg, offset + i + 1);

  return a;
}

ccl_device void svm_node_rgb_ramp(
    KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
{
  uint fac_offset, color_offset, alpha_offset;
  uint interpolate = node.z;

  decode_node_uchar4(node.y, &fac_offset, &color_offset, &alpha_offset, NULL);

  uint table_size = read_node(kg, offset).x;

  float fac = stack_load_float(stack, fac_offset);
  float4 color = rgb_ramp_lookup(kg, *offset, fac, interpolate, false, table_size);

  if (stack_valid(color_offset))
    stack_store_float3(stack, color_offset, float4_to_float3(color));
  if (stack_valid(alpha_offset))
    stack_store_float(stack, alpha_offset, color.w);

  *offset += table_size;
}

ccl_device void svm_node_curves(
    KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
{
  uint fac_offset, color_offset, out_offset;
  decode_node_uchar4(node.y, &fac_offset, &color_offset, &out_offset, NULL);

  uint table_size = read_node(kg, offset).x;

  float fac = stack_load_float(stack, fac_offset);
  float3 color = stack_load_float3(stack, color_offset);

  const float min_x = __int_as_float(node.z), max_x = __int_as_float(node.w);
  const float range_x = max_x - min_x;
  const float3 relpos = (color - make_float3(min_x, min_x, min_x)) / range_x;

  float r = rgb_ramp_lookup(kg, *offset, relpos.x, true, true, table_size).x;
  float g = rgb_ramp_lookup(kg, *offset, relpos.y, true, true, table_size).y;
  float b = rgb_ramp_lookup(kg, *offset, relpos.z, true, true, table_size).z;

  color = (1.0f - fac) * color + fac * make_float3(r, g, b);
  stack_store_float3(stack, out_offset, color);

  *offset += table_size;
}

CCL_NAMESPACE_END

#endif /* __SVM_RAMP_H__ */