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Differential D15348 Diff 53189 source/blender/blenlib/BLI_length_parameterize.hh

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source/blender/blenlib/BLI_length_parameterize.hh

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namespace blender::length_parameterize { namespace blender::length_parameterize {
/** /**
* Return the size of the necessary lengths array for a group of points, taking into account the * Return the size of the necessary lengths array for a group of points, taking into account the
* possible last cyclic segment. * possible last cyclic segment.
* *
* \note This is the same as #bke::curves::curve_segment_num. * \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; return cyclic ? points_num : points_num - 1;
} }
/** /**
* Accumulate the length of the next segment into each point. * Accumulate the length of the next segment into each point.
*/ */
template<typename T> template<typename T>
void accumulate_lengths(const Span<T> values, const bool cyclic, MutableSpan<float> lengths) 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; float length = 0.0f;
for (const int i : IndexRange(values.size() - 1)) { for (const int i : IndexRange(values.size() - 1)) {
length += math::distance(values[i], values[i + 1]); length += math::distance(values[i], values[i + 1]);
lengths[i] = length; lengths[i] = length;
} }
if (cyclic) { if (cyclic) {
lengths.last() = length + math::distance(values.last(), values.first()); lengths.last() = length + math::distance(values.last(), values.first());
} }
} }
template<typename T> template<typename T>
void linear_interpolation(const Span<T> src, inline void linear_interpolation(const Span<T> src,
const Span<int> indices, const Span<int> indices,
const Span<float> factors, const Span<float> factors,
MutableSpan<T> dst) MutableSpan<T> dst)
{ {
BLI_assert(indices.size() == factors.size()); BLI_assert(indices.size() == factors.size());
BLI_assert(indices.size() == dst.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 (const int i : dst.index_range()) {
for (int i = indices.index_range().last(); i > 0; i--) { const int prev_index = indices[i];
if (indices[i] != last_src_index) { const float factor = factors[i];
break; 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)) { const float total_length = lengths.last();
dst[i] = math::interpolate(src[indices[i]], src[indices[i] + 1], factors[i]); 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 * Find evenly spaced samples along the length.
HooglyBooglyUnsubmitted
Done
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}
/**
- * Find evenly spaced samples along the length.
+ * Find evenly spaced samples along the lengths.
*
* \param accumulated_segment_lengths: The accumulated lengths of the original elements being
HooglyBoogly:
* 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.
* *
* \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 segments and true otherwise.
HooglyBooglyUnsubmitted
Done
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* sampled. Could be calculated by #accumulate_lengths.
- * \param include_last_point: Generally false for cyclic segments and true otherwise.
+ * \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.
HooglyBoogly:
* \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, void sample_uniform(Span<float> accumulated_segment_lengths,
bool cyclic, bool include_last_point,
MutableSpan<int> indices, MutableSpan<int> r_segment_indices,
MutableSpan<float> factors); MutableSpan<float> r_factors);
/** /**
* For each provided sample length, find the segment index and interpolation factor. * For each provided sample length, find the segment index and interpolation factor.
* *
* \param lengths: The accumulated lengths of the original elements being sampled. * \param accumulated_segment_lengths: The accumulated lengths of the original elements being
* Could be calculated by #accumulate_lengths. * sampled. Could be calculated by #accumulate_lengths.
* \param sample_lengths: Sampled locations in the #lengths array. Must be sorted and is expected * \param sample_lengths: Sampled locations in the #lengths array. Must be sorted and is expected
* to be within the range of the #lengths values. * to be within the range of the #lengths values.
* \param cyclic: Whether the points described by the #lengths input is cyclic. This is likely * \param r_segment_indices: The index of the previous point at each sample.
* redundant information theoretically. * \param r_factors: The portion of the length in each segment at each sample.
* \param indices: The index of the previous point at each sample.
* \param factors: The portion of the length in each segment at each sample.
*/ */
void create_samples_from_sorted_lengths(Span<float> lengths, void sample_at_lengths(Span<float> accumulated_segment_lengths,
Span<float> sample_lengths, Span<float> sample_lengths,
bool cyclic, MutableSpan<int> r_segment_indices,
MutableSpan<int> indices, MutableSpan<float> r_factors);
MutableSpan<float> factors);
} // namespace blender::length_parameterize } // namespace blender::length_parameterize