Hans Goudey
eb40b231f9
lengths along a set of points. This can be used for the sample curves node, or finding new points along a curve when extending or shrinking it. This commit uses it in the snake hook brush as an example. The logic is similar to the uniform length sampling, but the next sample length is retrieved from the input instead of multiplication. For the sample node in the future, though this sort of sampling can be potentially done more efficiently for specific curve types besides poly curves, it's simpler, at least as a start, to work on a set of evaluated points that can be treated like a poly curve. Differential Revision: https://developer.blender.org/D14571
99 lines
3.4 KiB
C++
99 lines
3.4 KiB
C++
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#pragma once
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/** \file
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* \ingroup bli
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*/
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#include "BLI_math_base.hh"
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#include "BLI_math_color.hh"
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#include "BLI_math_vector.hh"
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#include "BLI_vector.hh"
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namespace blender::length_parameterize {
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/**
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* Return the size of the necessary lengths array for a group of points, taking into account the
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* possible last cyclic segment.
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*
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* \note This is the same as #bke::curves::curve_segment_size.
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*/
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inline int lengths_num(const int points_num, const bool cyclic)
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{
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return cyclic ? points_num : points_num - 1;
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}
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/**
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* Accumulate the length of the next segment into each point.
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*/
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template<typename T>
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void accumulate_lengths(const Span<T> values, const bool cyclic, MutableSpan<float> lengths)
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{
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BLI_assert(lengths.size() == lengths_num(values.size(), cyclic));
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float length = 0.0f;
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for (const int i : IndexRange(values.size() - 1)) {
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length += math::distance(values[i], values[i + 1]);
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lengths[i] = length;
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}
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if (cyclic) {
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lengths.last() = length + math::distance(values.last(), values.first());
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}
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}
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template<typename T>
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void linear_interpolation(const Span<T> src,
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const Span<int> indices,
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const Span<float> factors,
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MutableSpan<T> dst)
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{
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BLI_assert(indices.size() == factors.size());
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BLI_assert(indices.size() == dst.size());
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const int last_src_index = src.index_range().last();
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int cyclic_sample_count = 0;
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for (int i = indices.index_range().last(); i > 0; i--) {
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if (indices[i] != last_src_index) {
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break;
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}
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dst[i] = math::interpolate(src.last(), src.first(), factors[i]);
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cyclic_sample_count++;
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}
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for (const int i : dst.index_range().drop_back(cyclic_sample_count)) {
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dst[i] = math::interpolate(src[indices[i]], src[indices[i] + 1], factors[i]);
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}
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}
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/**
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* Find the given number of points, evenly spaced along the provided length. For non-cyclic
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* sequences, the first point will always be included, and last point will always be included if
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* the #count is greater than zero. For cyclic sequences, the first point will always be included.
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*
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* \warning The #count argument must be greater than zero.
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*/
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void create_uniform_samples(Span<float> lengths,
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bool cyclic,
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MutableSpan<int> indices,
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MutableSpan<float> factors);
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/**
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* For each provided sample length, find the segment index and interpolation factor.
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*
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* \param lengths: The accumulated lengths of the original elements being sampled.
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* Could be calculated by #accumulate_lengths.
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* \param sample_lengths: Sampled locations in the #lengths array. Must be sorted and is expected
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* to be within the range of the #lengths values.
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* \param cyclic: Whether the points described by the #lenghts input is cyclic. This is likely
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* redundant information theoretically.
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* \param indices: The index of the previous point at each sample.
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* \param factors: The portion of the length in each segment at each sample.
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*/
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void create_samples_from_sorted_lengths(Span<float> lengths,
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Span<float> sample_lengths,
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bool cyclic,
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MutableSpan<int> indices,
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MutableSpan<float> factors);
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} // namespace blender::length_parameterize
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