symmetric_separable_blur_weights.cc

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#include <cstdint>
#include <memory>
 
#include "BLI_array.hh"
#include "BLI_hash.hh"
#include "BLI_index_range.hh"
#include "BLI_math_base.hh"
 
#include "RE_pipeline.h"
 
#include "GPU_texture.hh"
 
#include "COM_context.hh"
#include "COM_result.hh"
#include "COM_symmetric_separable_blur_weights.hh"
 
namespace blender::compositor {
 
/* --------------------------------------------------------------------
 * Symmetric Separable Blur Weights Key.
 */
 
SymmetricSeparableBlurWeightsKey::SymmetricSeparableBlurWeightsKey(int type, float radius)
    : type(type), radius(radius)
{
}
 
uint64_t SymmetricSeparableBlurWeightsKey::hash() const
{
  return get_default_hash(type, radius);
}
 
bool operator==(const SymmetricSeparableBlurWeightsKey &a,
                const SymmetricSeparableBlurWeightsKey &b)
{
  return a.type == b.type && a.radius == b.radius;
}
 
/* --------------------------------------------------------------------
 * Symmetric Separable Blur Weights.
 */
 
SymmetricSeparableBlurWeights::SymmetricSeparableBlurWeights(Context &context,
                                                             int type,
                                                             float radius)
    : result(context.create_result(ResultType::Float))
{
  /* The size of filter is double the radius plus 1, but since the filter is symmetric, we only
   * compute half of it and no doubling happens. We add 1 to make sure the filter size is always
   * odd and there is a center weight. */
  const int size = math::ceil(radius) + 1;
  weights_ = Array<float>(size);
 
  float sum = 0.0f;
 
  /* First, compute the center weight. */
  const float center_weight = RE_filter_value(type, 0.0f);
  weights_[0] = center_weight;
  sum += center_weight;
 
  /* Second, compute the other weights in the positive direction, making sure to add double the
   * weight to the sum of weights because the filter is symmetric and we only loop over half of
   * it. Skip the center weight already computed by dropping the front index. */
  const float scale = radius > 0.0f ? 1.0f / radius : 0.0f;
  for (const int i : weights_.index_range().drop_front(1)) {
    const float weight = RE_filter_value(type, i * scale);
    weights_[i] = weight;
    sum += weight * 2.0f;
  }
 
  /* Finally, normalize the weights. */
  for (const int i : weights_.index_range()) {
    weights_[i] /= sum;
  }
 
  if (context.use_gpu()) {
    this->result.allocate_texture(Domain(int2(size, 1)), false);
    GPU_texture_update(this->result, GPU_DATA_FLOAT, weights_.data());
 
    /* CPU-side data no longer needed, so free it. */
    weights_ = Array<float>();
  }
  else {
    this->result.wrap_external(weights_.data(), int2(size, 1));
  }
}
 
SymmetricSeparableBlurWeights::~SymmetricSeparableBlurWeights()
{
  this->result.release();
}
 
/* --------------------------------------------------------------------
 * Symmetric Separable Blur Weights Container.
 */
 
void SymmetricSeparableBlurWeightsContainer::reset()
{
  /* First, delete all resources that are no longer needed. */
  map_.remove_if([](auto item) { return !item.value->needed; });
 
  /* Second, reset the needed status of the remaining resources to false to ready them to track
   * their needed status for the next evaluation. */
  for (auto &value : map_.values()) {
    value->needed = false;
  }
}
 
Result &SymmetricSeparableBlurWeightsContainer::get(Context &context, int type, float radius)
{
  const SymmetricSeparableBlurWeightsKey key(type, radius);
 
  auto &weights = *map_.lookup_or_add_cb(key, [&]() {
    return std::make_unique<SymmetricSeparableBlurWeights>(context, type, radius);
  });
 
  weights.needed = true;
  return weights.result;
}
 
}  // namespace blender::compositor