[Bf-blender-cvs] [ab444a80a28] master: BLI: refactor length parameterization
Jacques Lucke
noreply at git.blender.org
Sat Jul 2 21:52:11 CEST 2022
Commit: ab444a80a280e125b3e4d002941504d56f340ced
Author: Jacques Lucke
Date: Sat Jul 2 21:51:45 2022 +0200
Branches: master
https://developer.blender.org/rBab444a80a280e125b3e4d002941504d56f340ced
BLI: refactor length parameterization
This refactor had two main goals:
* Simplify the sampling code by using an algorithm with fewer special cases.
* Generalize the sampling to support non-sorted samples.
The `SampleSegmentHint` optimization was inspired by `ValueAccessor` from
OpenVDB and improves performance 2x in my test cases.
Differential Revision: https://developer.blender.org/D15348
===================================================================
M source/blender/blenlib/BLI_length_parameterize.hh
M source/blender/blenlib/intern/length_parameterize.cc
M source/blender/blenlib/tests/BLI_length_parameterize_test.cc
M source/blender/editors/sculpt_paint/curves_sculpt_brush.cc
M source/blender/geometry/intern/resample_curves.cc
===================================================================
diff --git a/source/blender/blenlib/BLI_length_parameterize.hh b/source/blender/blenlib/BLI_length_parameterize.hh
index ec0fabb75b4..ff957d92263 100644
--- a/source/blender/blenlib/BLI_length_parameterize.hh
+++ b/source/blender/blenlib/BLI_length_parameterize.hh
@@ -19,7 +19,7 @@ namespace blender::length_parameterize {
*
* \note This is the same as #bke::curves::curve_segment_num.
*/
-inline int lengths_num(const int points_num, const bool cyclic)
+inline int segments_num(const int points_num, const bool cyclic)
{
return cyclic ? points_num : points_num - 1;
}
@@ -30,7 +30,7 @@ inline int lengths_num(const int points_num, const bool cyclic)
template<typename T>
void accumulate_lengths(const Span<T> values, const bool cyclic, MutableSpan<float> lengths)
{
- BLI_assert(lengths.size() == lengths_num(values.size(), cyclic));
+ BLI_assert(lengths.size() == segments_num(values.size(), cyclic));
float length = 0.0f;
for (const int i : IndexRange(values.size() - 1)) {
length += math::distance(values[i], values[i + 1]);
@@ -42,57 +42,122 @@ void accumulate_lengths(const Span<T> values, const bool cyclic, MutableSpan<flo
}
template<typename T>
-void linear_interpolation(const Span<T> src,
- const Span<int> indices,
- const Span<float> factors,
- MutableSpan<T> dst)
+inline void linear_interpolation(const Span<T> src,
+ const Span<int> indices,
+ const Span<float> factors,
+ MutableSpan<T> dst)
{
BLI_assert(indices.size() == factors.size());
BLI_assert(indices.size() == dst.size());
- const int last_src_index = src.index_range().last();
+ const int last_src_index = src.size() - 1;
- int cyclic_sample_count = 0;
- for (int i = indices.index_range().last(); i > 0; i--) {
- if (indices[i] != last_src_index) {
- break;
+ for (const int i : dst.index_range()) {
+ const int prev_index = indices[i];
+ const float factor = factors[i];
+ const bool is_cyclic_case = prev_index == last_src_index;
+ if (is_cyclic_case) {
+ dst[i] = math::interpolate(src.last(), src.first(), factor);
+ }
+ else {
+ dst[i] = math::interpolate(src[prev_index], src[prev_index + 1], factor);
+ }
+ }
+}
+
+/**
+ * Passing this to consecutive calls of #sample_at_length can increase performance.
+ */
+struct SampleSegmentHint {
+ int segment_index = -1;
+ float segment_start;
+ float segment_length_inv;
+};
+
+/**
+ * \param accumulated_segment_lengths: Lengths of individual segments added up.
+ * \param sample_length: The position to sample at.
+ * \param r_segment_index: Returns the index of the segment that #sample_length is in.
+ * \param r_factor: Returns the position within the segment.
+ *
+ * \note #sample_length must not be outside of any segment.
+ */
+inline void sample_at_length(const Span<float> accumulated_segment_lengths,
+ float sample_length,
+ int &r_segment_index,
+ float &r_factor,
+ SampleSegmentHint *hint = nullptr)
+{
+ /* Use a shorter variable name. */
+ const Span<float> lengths = accumulated_segment_lengths;
+
+ BLI_assert(lengths.size() > 0);
+ BLI_assert(sample_length >= 0.0f);
+ BLI_assert(sample_length <= lengths.last());
+
+ if (hint != nullptr && hint->segment_index >= 0) {
+ const float length_in_segment = sample_length - hint->segment_start;
+ const float factor = length_in_segment * hint->segment_length_inv;
+ if (factor >= 0.0f && factor < 1.0f) {
+ r_segment_index = hint->segment_index;
+ r_factor = factor;
+ return;
}
- dst[i] = math::interpolate(src.last(), src.first(), factors[i]);
- cyclic_sample_count++;
}
- for (const int i : dst.index_range().drop_back(cyclic_sample_count)) {
- dst[i] = math::interpolate(src[indices[i]], src[indices[i] + 1], factors[i]);
+ const float total_length = lengths.last();
+ if (sample_length >= total_length) {
+ /* Return the last position on the last segment. */
+ r_segment_index = lengths.size() - 1;
+ r_factor = 1.0f;
+ return;
+ }
+
+ const int prev_point_index = std::upper_bound(lengths.begin(), lengths.end(), sample_length) -
+ lengths.begin();
+ const float segment_start = prev_point_index == 0 ? 0.0f : lengths[prev_point_index - 1];
+ const float segment_end = lengths[prev_point_index];
+ const float segment_length = segment_end - segment_start;
+ const float segment_length_inv = safe_divide(1.0f, segment_length);
+ const float length_in_segment = sample_length - segment_start;
+ const float factor = length_in_segment * segment_length_inv;
+
+ r_segment_index = prev_point_index;
+ r_factor = factor;
+
+ if (hint != nullptr) {
+ hint->segment_index = r_segment_index;
+ hint->segment_start = segment_start;
+ hint->segment_length_inv = segment_length_inv;
}
}
/**
- * Find the given number of points, evenly spaced along the provided length. For non-cyclic
- * sequences, the first point will always be included, and last point will always be included if
- * the #count is greater than zero. For cyclic sequences, the first point will always be included.
+ * Find evenly spaced samples along the lengths.
*
- * \warning The #count argument must be greater than zero.
+ * \param accumulated_segment_lengths: The accumulated lengths of the original elements being
+ * sampled. Could be calculated by #accumulate_lengths.
+ * \param include_last_point: Generally false for cyclic sequences and true otherwise.
+ * \param r_segment_indices: The index of the previous point at each sample.
+ * \param r_factors: The portion of the length in each segment at each sample.
*/
-void create_uniform_samples(Span<float> lengths,
- bool cyclic,
- MutableSpan<int> indices,
- MutableSpan<float> factors);
+void sample_uniform(Span<float> accumulated_segment_lengths,
+ bool include_last_point,
+ MutableSpan<int> r_segment_indices,
+ MutableSpan<float> r_factors);
/**
* For each provided sample length, find the segment index and interpolation factor.
*
- * \param lengths: The accumulated lengths of the original elements being sampled.
- * Could be calculated by #accumulate_lengths.
+ * \param accumulated_segment_lengths: The accumulated lengths of the original elements being
+ * sampled. Could be calculated by #accumulate_lengths.
* \param sample_lengths: Sampled locations in the #lengths array. Must be sorted and is expected
* to be within the range of the #lengths values.
- * \param cyclic: Whether the points described by the #lengths input is cyclic. This is likely
- * redundant information theoretically.
- * \param indices: The index of the previous point at each sample.
- * \param factors: The portion of the length in each segment at each sample.
+ * \param r_segment_indices: The index of the previous point at each sample.
+ * \param r_factors: The portion of the length in each segment at each sample.
*/
-void create_samples_from_sorted_lengths(Span<float> lengths,
- Span<float> sample_lengths,
- bool cyclic,
- MutableSpan<int> indices,
- MutableSpan<float> factors);
+void sample_at_lengths(Span<float> accumulated_segment_lengths,
+ Span<float> sample_lengths,
+ MutableSpan<int> r_segment_indices,
+ MutableSpan<float> r_factors);
} // namespace blender::length_parameterize
diff --git a/source/blender/blenlib/intern/length_parameterize.cc b/source/blender/blenlib/intern/length_parameterize.cc
index e18b048e96d..06cca281510 100644
--- a/source/blender/blenlib/intern/length_parameterize.cc
+++ b/source/blender/blenlib/intern/length_parameterize.cc
@@ -1,144 +1,58 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
#include "BLI_length_parameterize.hh"
+#include "BLI_task.hh"
namespace blender::length_parameterize {
-void create_uniform_samples(const Span<float> lengths,
- const bool cyclic,
- MutableSpan<int> indices,
- MutableSpan<float> factors)
+void sample_uniform(const Span<float> lengths,
+ const bool include_last_point,
+ MutableSpan<int> r_segment_indices,
+ MutableSpan<float> r_factors)
{
- const int count = indices.size();
+ const int count = r_segment_indices.size();
BLI_assert(count > 0);
BLI_assert(lengths.size() >= 1);
BLI_assert(std::is_sorted(lengths.begin(), lengths.end()));
- const int segments_num = lengths.size();
- const int points_num = cyclic ? segments_num : segments_num + 1;
- indices.first() = 0;
- factors.first() = 0.0f;
if (count == 1) {
+ r_segment_indices[0] = 0;
+ r_factors[0] = 0.0f;
return;
}
-
const float total_length = lengths.last();
- if (total_length == 0.0f) {
- indices.fill(0);
- factors.fill(0.0f);
- return;
- }
-
- const float step_length = total_length / (count - (cyclic ? 0 : 1));
- const float step_length_inv = 1.0f / step_length;
-
- int i_dst = 1;
- /* Store the length at the previous point in a variable so it can start out at zero
- * (the lengths array doesn't contain 0 for the first point). */
- float prev_length = 0.0f;
- for (const int i_src : IndexRange(points_num - 1)) {
- const float next_length = lengths[i_src];
- const float segment_length = next_length - prev_length;
- if (segment_length == 0.0f) {
- continue;
- }
- /* Add every sample that fits in this segment. */
- const float segment_length_inv = 1.0f / segment_length;
- const int segment_samples_num = std::ceil(next_length * step_length_inv - i_dst);
- indices.slice(i_dst, segment_samples_num).fill(i_src);
-
- for (const int i : IndexRange(i_dst, s
@@ Diff output truncated at 10240 characters. @@
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