diff options
Diffstat (limited to 'source/blender/blenlib/BLI_length_parameterize.hh')
| -rw-r--r-- | source/blender/blenlib/BLI_length_parameterize.hh | 135 |
1 files changed, 100 insertions, 35 deletions
diff --git a/source/blender/blenlib/BLI_length_parameterize.hh b/source/blender/blenlib/BLI_length_parameterize.hh index f13641c3a65..c44bb94f65d 100644 --- a/source/blender/blenlib/BLI_length_parameterize.hh +++ b/source/blender/blenlib/BLI_length_parameterize.hh @@ -17,9 +17,9 @@ namespace blender::length_parameterize { * Return the size of the necessary lengths array for a group of points, taking into account the * possible last cyclic segment. * - * \note This is the same as #bke::curves::curve_segment_num. + * \note This is the same as #bke::curves::segments_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 #lenghts 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 |