blender/intern/cycles/kernel/svm/svm_checker.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

/* Checker */

ccl_device_noinline float svm_checker(float3 p)
{
  /* avoid precision issues on unit coordinates */
  p.x = (p.x + 0.000001f) * 0.999999f;
  p.y = (p.y + 0.000001f) * 0.999999f;
  p.z = (p.z + 0.000001f) * 0.999999f;

  int xi = abs(float_to_int(floorf(p.x)));
  int yi = abs(float_to_int(floorf(p.y)));
  int zi = abs(float_to_int(floorf(p.z)));

  return ((xi % 2 == yi % 2) == (zi % 2)) ? 1.0f : 0.0f;
}

ccl_device void svm_node_tex_checker(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node)
{
  uint co_offset, color1_offset, color2_offset, scale_offset;
  uint color_offset, fac_offset;

  decode_node_uchar4(node.y, &co_offset, &color1_offset, &color2_offset, &scale_offset);
  decode_node_uchar4(node.z, &color_offset, &fac_offset, NULL, NULL);

  float3 co = stack_load_float3(stack, co_offset);
  float3 color1 = stack_load_float3(stack, color1_offset);
  float3 color2 = stack_load_float3(stack, color2_offset);
  float scale = stack_load_float_default(stack, scale_offset, node.w);

  float f = svm_checker(co * scale);

  if (stack_valid(color_offset))
    stack_store_float3(stack, color_offset, (f == 1.0f) ? color1 : color2);
  if (stack_valid(fac_offset))
    stack_store_float(stack, fac_offset, f);
}

CCL_NAMESPACE_END