78 lines
2.1 KiB
C++
78 lines
2.1 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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* Generic algorithms for finding the largest and smallest elements in a span.
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*/
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#include <optional>
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#include "BLI_math_vector.hh"
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#include "BLI_task.hh"
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namespace blender::bounds {
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template<typename T> struct MinMaxResult {
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T min;
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T max;
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};
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/**
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* Find the smallest and largest values element-wise in the span.
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*/
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template<typename T> static std::optional<MinMaxResult<T>> min_max(Span<T> values)
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{
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if (values.is_empty()) {
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return std::nullopt;
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}
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const MinMaxResult<T> init{values.first(), values.first()};
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return threading::parallel_reduce(
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values.index_range(),
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1024,
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init,
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[&](IndexRange range, const MinMaxResult<T> &init) {
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MinMaxResult<T> result = init;
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for (const int i : range) {
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math::min_max(values[i], result.min, result.max);
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}
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return result;
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},
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[](const MinMaxResult<T> &a, const MinMaxResult<T> &b) {
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return MinMaxResult<T>{math::min(a.min, b.min), math::max(a.max, b.max)};
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});
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}
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/**
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* Find the smallest and largest values element-wise in the span, adding the radius to each element
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* first. The template type T is expected to have an addition operator implemented with RadiusT.
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*/
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template<typename T, typename RadiusT>
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static std::optional<MinMaxResult<T>> min_max_with_radii(Span<T> values, Span<RadiusT> radii)
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{
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BLI_assert(values.size() == radii.size());
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if (values.is_empty()) {
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return std::nullopt;
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}
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const MinMaxResult<T> init{values.first(), values.first()};
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return threading::parallel_reduce(
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values.index_range(),
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1024,
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init,
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[&](IndexRange range, const MinMaxResult<T> &init) {
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MinMaxResult<T> result = init;
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for (const int i : range) {
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result.min = math::min(values[i] - radii[i], result.min);
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result.max = math::max(values[i] + radii[i], result.max);
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}
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return result;
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},
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[](const MinMaxResult<T> &a, const MinMaxResult<T> &b) {
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return MinMaxResult<T>{math::min(a.min, b.min), math::max(a.max, b.max)};
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});
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}
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} // namespace blender::bounds
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