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Fix: Splines: Use consistent bezier linear interpolation method 

While the method of interpolating based on the curve length at each
evaluated point may be useful in some situations, for now it's best to
be consistent with the existing methods in Blender, so this commit adds
a simple linear-based-on-resolution sampling method to bezier splines.
This commit is contained in:
Hans Goudey 2021-05-04 17:27:20 -05:00
parent d18be66a54
commit 1f5710326f
1 changed files with 35 additions and 42 deletions
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77
source/blender/blenkernel/intern/spline_bezier.cc
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@ -296,6 +296,40 @@ Span<int> BezierSpline::control_point_offsets() const
return offsets;
}
static void calculate_mappings_linear_resolution(Span<int> offsets,
const int size,
const int resolution,
const bool is_cyclic,
MutableSpan<float> r_mappings)
{
const float first_segment_len_inv = 1.0f / offsets[1];
for (const int i : IndexRange(0, offsets[1])) {
r_mappings[i] = i * first_segment_len_inv;
}
const int grain_size = std::max(2048 / resolution, 1);
blender::parallel_for(IndexRange(1, size - 2), grain_size, [&](IndexRange range) {
for (const int i_control_point : range) {
const int segment_len = offsets[i_control_point + 1] - offsets[i_control_point];
const float segment_len_inv = 1.0f / segment_len;
for (const int i : IndexRange(segment_len)) {
r_mappings[offsets[i_control_point] + i] = i_control_point + i * segment_len_inv;
}
}
});
if (is_cyclic) {
const int last_segment_len = offsets[size - 1] - offsets[size - 2];
const float last_segment_len_inv = 1.0f / last_segment_len;
for (const int i : IndexRange(last_segment_len)) {
r_mappings[offsets[size - 1] + i] = size - 1 + i * last_segment_len_inv;
}
}
else {
r_mappings.last() = size - 1;
}
}
/**
* Returns non-owning access to an array of values containing the information necessary to
* interpolate values from the original control points to evaluated points. The control point
@ -325,49 +359,8 @@ Span<float> BezierSpline::evaluated_mappings() const
}
Span<int> offsets = this->control_point_offsets();
Span<float> lengths = this->evaluated_lengths();
/* Subtract one from the index into the lengths array to get the length
* at the start point rather than the length at the end of the edge. */
const float first_segment_len = lengths[offsets[1] - 1];
for (const int eval_index : IndexRange(0, offsets[1])) {
const float point_len = eval_index == 0 ? 0.0f : lengths[eval_index - 1];
const float length_factor = (first_segment_len == 0.0f) ? 0.0f : 1.0f / first_segment_len;
mappings[eval_index] = point_len * length_factor;
}
const int grain_size = std::max(512 / resolution_, 1);
blender::parallel_for(IndexRange(1, size - 2), grain_size, [&](IndexRange range) {
for (const int i : range) {
const float segment_start_len = lengths[offsets[i] - 1];
const float segment_end_len = lengths[offsets[i + 1] - 1];
const float segment_len = segment_end_len - segment_start_len;
const float length_factor = (segment_len == 0.0f) ? 0.0f : 1.0f / segment_len;
for (const int eval_index : IndexRange(offsets[i], offsets[i + 1] - offsets[i])) {
const float factor = (lengths[eval_index - 1] - segment_start_len) * length_factor;
mappings[eval_index] = i + factor;
}
}
});
if (is_cyclic_) {
const float segment_start_len = lengths[offsets.last() - 1];
const float segment_end_len = this->length();
const float segment_len = segment_end_len - segment_start_len;
const float length_factor = (segment_len == 0.0f) ? 0.0f : 1.0f / segment_len;
for (const int eval_index : IndexRange(offsets.last(), eval_size - offsets.last())) {
const float factor = (lengths[eval_index - 1] - segment_start_len) * length_factor;
mappings[eval_index] = size - 1 + factor;
}
mappings.last() = 0.0f;
}
else {
mappings.last() = size - 1;
}
calculate_mappings_linear_resolution(offsets, size, resolution_, is_cyclic_, mappings);
mapping_cache_dirty_ = false;
return mappings;