lookup_table.h

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/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
 *
 * SPDX-License-Identifier: Apache-2.0 */
 
#pragma once
 
#include "kernel/globals.h"
#include "kernel/types.h"
 
CCL_NAMESPACE_BEGIN
 
/* Interpolated lookup table access */
 
ccl_device float lookup_table_read(KernelGlobals kg, float x, const int offset, const int size)
{
  x = saturatef(x) * (size - 1);
 
  const int index = min(float_to_int(x), size - 1);
  const int nindex = min(index + 1, size - 1);
  const float t = x - index;
 
  const float data0 = kernel_data_fetch(lookup_table, index + offset);
  if (t == 0.0f) {
    return data0;
  }
 
  const float data1 = kernel_data_fetch(lookup_table, nindex + offset);
  return (1.0f - t) * data0 + t * data1;
}
 
ccl_device float lookup_table_read_2D(
    KernelGlobals kg, const float x, float y, const int offset, const int xsize, const int ysize)
{
  y = saturatef(y) * (ysize - 1);
 
  const int index = min(float_to_int(y), ysize - 1);
  const int nindex = min(index + 1, ysize - 1);
  const float t = y - index;
 
  const float data0 = lookup_table_read(kg, x, offset + xsize * index, xsize);
  if (t == 0.0f) {
    return data0;
  }
 
  const float data1 = lookup_table_read(kg, x, offset + xsize * nindex, xsize);
  return (1.0f - t) * data0 + t * data1;
}
 
ccl_device float lookup_table_read_3D(KernelGlobals kg,
                                      const float x,
                                      float y,
                                      float z,
                                      const int offset,
                                      const int xsize,
                                      const int ysize,
                                      const int zsize)
{
  z = saturatef(z) * (zsize - 1);
 
  const int index = min(float_to_int(z), zsize - 1);
  const int nindex = min(index + 1, zsize - 1);
  const float t = z - index;
 
  const float data0 = lookup_table_read_2D(kg, x, y, offset + xsize * ysize * index, xsize, ysize);
  if (t == 0.0f) {
    return data0;
  }
 
  const float data1 = lookup_table_read_2D(
      kg, x, y, offset + xsize * ysize * nindex, xsize, ysize);
  return (1.0f - t) * data0 + t * data1;
}
 
CCL_NAMESPACE_END