1 files changed, 93 insertions, 0 deletions
diff --git a/source/blender/compositor/realtime_compositor/cached_resources/intern/symmetric_separable_blur_weights.cc b/source/blender/compositor/realtime_compositor/cached_resources/intern/symmetric_separable_blur_weights.cc
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+++ b/source/blender/compositor/realtime_compositor/cached_resources/intern/symmetric_separable_blur_weights.cc
@@ -0,0 +1,93 @@
+/* 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_base.hh"
+
+#include "RE_pipeline.h"
+
+#include "GPU_shader.h"
+#include "GPU_texture.h"
+
+#include "COM_symmetric_separable_blur_weights.hh"
+
+namespace blender::realtime_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_2(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(int type, float radius)
+{
+  /* 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;
+  Array<float> weights(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;
+  }
+
+  texture_ = GPU_texture_create_1d("Weights", size, 1, GPU_R16F, weights.data());
+}
+
+SymmetricSeparableBlurWeights::~SymmetricSeparableBlurWeights()
+{
+  GPU_texture_free(texture_);
+}
+
+void SymmetricSeparableBlurWeights::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 SymmetricSeparableBlurWeights::unbind_as_texture() const
+{
+  GPU_texture_unbind(texture_);
+}
+
+}  // namespace blender::realtime_compositor