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Cleanup: Remove unnecessary NURBS optimization 

The step after calculating the NURBS basis for a single evaluated
point trimmed extra zeroes from the weights. However, in practice
this rarely did anything, only for the first and last evaluated point
of certain knot configurations. Remove it in order to simplify code.

Also use a separate span for the result, to clarify its length.
This commit is contained in:
Hans Goudey 2022-03-11 17:48:33 -06:00
parent 3b16530aa1
commit 34a61ceeaa
1 changed files with 16 additions and 17 deletions
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33
source/blender/blenkernel/intern/spline_nurbs.cc
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@ -247,35 +247,34 @@ static void calculate_basis_for_point(const float parameter,
}
basis_buffer[size + degree] = 0.0f;
MutableSpan<float> weights = basis_buffer.slice(start, degree + 1);
for (const int i_order : IndexRange(2, degree)) {
if (end + i_order >= size + degree + 1) {
if (end + i_order >= knots.size()) {
end = size + degree - i_order;
}
for (const int i : IndexRange(start, end - start + 1)) {
for (const int i : IndexRange(end - start + 1)) {
const int knot_index = start + i;
float new_basis = 0.0f;
if (basis_buffer[i] != 0.0f) {
new_basis += ((t - knots[i]) * basis_buffer[i]) / (knots[i + i_order - 1] - knots[i]);
if (weights[i] != 0.0f) {
new_basis += ((t - knots[knot_index]) * basis_buffer[knot_index]) /
(knots[knot_index + i_order - 1] - knots[knot_index]);
}
if (basis_buffer[i + 1] != 0.0f) {
new_basis += ((knots[i + i_order] - t) * basis_buffer[i + 1]) /
(knots[i + i_order] - knots[i + 1]);
if (basis_buffer[knot_index + 1] != 0.0f) {
new_basis += ((knots[knot_index + i_order] - t) * basis_buffer[knot_index + 1]) /
(knots[knot_index + i_order] - knots[knot_index + 1]);
}
basis_buffer[i] = new_basis;
weights[i] = new_basis;
}
}
/* Shrink the range of calculated values to avoid storing unnecessary zeros. */
while (basis_buffer[start] == 0.0f && start < end) {
start++;
}
while (basis_buffer[end] == 0.0f && end > start) {
end--;
}
weights.drop_front(end - start + 1).fill(0.0f);
basis_cache.weights.clear();
basis_cache.weights.extend(basis_buffer.slice(start, end - start + 1));
basis_cache.weights.extend(weights);
basis_cache.start_index = start;
}
@ -317,7 +316,7 @@ Span<NURBSpline::BasisCache> NURBSpline::calculate_basis_cache() const
BasisCache &basis = basis_cache[i];
calculate_basis_for_point(
parameter, size + (is_cyclic_ ? degree : 0), degree, knots, basis_buffer, basis);
BLI_assert(basis.weights.size() <= order);
BLI_assert(basis.weights.size() == order);
for (const int j : basis.weights.index_range()) {
const int point_index = (basis.start_index + j) % size;