1 files changed, 115 insertions, 0 deletions
diff --git a/source/blender/compositor/realtime_compositor/cached_resources/intern/symmetric_blur_weights.cc b/source/blender/compositor/realtime_compositor/cached_resources/intern/symmetric_blur_weights.cc
new file mode 100644
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+++ b/source/blender/compositor/realtime_compositor/cached_resources/intern/symmetric_blur_weights.cc
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <cstdint>
+
+#include "BLI_array.hh"
+#include "BLI_hash.hh"
+#include "BLI_index_range.hh"
+#include "BLI_math_vec_types.hh"
+#include "BLI_math_vector.hh"
+
+#include "RE_pipeline.h"
+
+#include "GPU_shader.h"
+#include "GPU_texture.h"
+
+#include "COM_symmetric_blur_weights.hh"
+
+namespace blender::realtime_compositor {
+
+/* --------------------------------------------------------------------
+ * Symmetric Blur Weights Key.
+ */
+
+SymmetricBlurWeightsKey::SymmetricBlurWeightsKey(int type, float2 radius)
+    : type(type), radius(radius)
+{
+}
+
+uint64_t SymmetricBlurWeightsKey::hash() const
+{
+  return get_default_hash_3(type, radius.x, radius.y);
+}
+
+bool operator==(const SymmetricBlurWeightsKey &a, const SymmetricBlurWeightsKey &b)
+{
+  return a.type == b.type && a.radius == b.radius;
+}
+
+/* --------------------------------------------------------------------
+ * Symmetric Blur Weights.
+ */
+
+SymmetricBlurWeights::SymmetricBlurWeights(int type, float2 radius)
+{
+  /* The full size of filter is double the radius plus 1, but since the filter is symmetric, we
+   * only compute a single quadrant of it and so no doubling happens. We add 1 to make sure the
+   * filter size is always odd and there is a center weight. */
+  const float2 scale = math::safe_divide(float2(1.0f), radius);
+  const int2 size = int2(math::ceil(radius)) + int2(1);
+  Array<float> weights(size.x * size.y);
+
+  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;
+
+  /* Then, compute the weights along the positive x axis, making sure to add double the weight to
+   * the sum of weights because the filter is symmetric and we only loop over the positive half
+   * of the x axis. Skip the center weight already computed by dropping the front index. */
+  for (const int x : IndexRange(size.x).drop_front(1)) {
+    const float weight = RE_filter_value(type, x * scale.x);
+    weights[x] = weight;
+    sum += weight * 2.0f;
+  }
+
+  /* Then, compute the weights along the positive y axis, making sure to add double the weight to
+   * the sum of weights because the filter is symmetric and we only loop over the positive half
+   * of the y axis. Skip the center weight already computed by dropping the front index. */
+  for (const int y : IndexRange(size.y).drop_front(1)) {
+    const float weight = RE_filter_value(type, y * scale.y);
+    weights[size.x * y] = weight;
+    sum += weight * 2.0f;
+  }
+
+  /* Then, compute the other weights in the upper right quadrant, making sure to add quadruple
+   * the weight to the sum of weights because the filter is symmetric and we only loop over one
+   * quadrant of it. Skip the weights along the y and x axis already computed by dropping the
+   * front index. */
+  for (const int y : IndexRange(size.y).drop_front(1)) {
+    for (const int x : IndexRange(size.x).drop_front(1)) {
+      const float weight = RE_filter_value(type, math::length(float2(x, y) * scale));
+      weights[size.x * y + x] = weight;
+      sum += weight * 4.0f;
+    }
+  }
+
+  /* Finally, normalize the weights. */
+  for (const int y : IndexRange(size.y)) {
+    for (const int x : IndexRange(size.x)) {
+      weights[size.x * y + x] /= sum;
+    }
+  }
+
+  texture_ = GPU_texture_create_2d("Weights", size.x, size.y, 1, GPU_R16F, weights.data());
+}
+
+SymmetricBlurWeights::~SymmetricBlurWeights()
+{
+  GPU_texture_free(texture_);
+}
+
+void SymmetricBlurWeights::bind_as_texture(GPUShader *shader, const char *texture_name) const
+{
+  const int texture_image_unit = GPU_shader_get_texture_binding(shader, texture_name);
+  GPU_texture_bind(texture_, texture_image_unit);
+}
+
+void SymmetricBlurWeights::unbind_as_texture() const
+{
+  GPU_texture_unbind(texture_);
+}
+
+}  // namespace blender::realtime_compositor