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GPv3: Refactor: ramer_douglas_peucker_simplify

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This refactors the `ramer_douglas_peucker_simplify` function to be more generic.

No functional changes expected.

Pull Request: https://projects.blender.org/blender/blender/pulls/110338
This commit is contained in:
Falk David
2023-07-21 12:44:36 +02:00
committed by Falk David
parent 4833dd931b
commit 8dd0faec54
2 changed files with 45 additions and 23 deletions
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63
source/blender/editors/grease_pencil/intern/grease_pencil_edit.cc
View File

@@ -403,45 +403,52 @@ static void GREASE_PENCIL_OT_stroke_smooth(wmOperatorType *ot)
/**
* An implementation of the Ramer-Douglas-Peucker algorithm.
*
* \param range: The range to simplify.
* \param epsilon: The threshold distance from the coord between two points for when a point
* in-between needs to be kept.
* \param dist_function: A function that computes the distance to a point at an index in the range.
* The IndexRange is a subrange of \a range and the index is an index relative to the subrange.
* \param points_to_delete: Writes true to the indecies for which the points should be removed.
* \returns the total number of points to remove.
*/
void ramer_douglas_peucker_simplify(const Span<float3> src,
const float epsilon,
MutableSpan<bool> points_to_delete)
int64_t ramer_douglas_peucker_simplify(const IndexRange range,
const float epsilon,
const FunctionRef<float(IndexRange, int64_t)> dist_function,
MutableSpan<bool> points_to_delete)
{
BLI_assert(src.size() == points_to_delete.size());
/* Mark all points to not be removed. */
points_to_delete.fill(false);
points_to_delete.slice(range).fill(false);
int64_t total_points_to_remove = 0;
Stack<IndexRange> stack;
stack.push(src.index_range());
stack.push(range);
while (!stack.is_empty()) {
const IndexRange range = stack.pop();
const Span<float3> slice = src.slice(range);
const IndexRange sub_range = stack.pop();
/* Compute the maximum distance and the corresponding distance. */
float max_dist = -1.0f;
int max_index = -1;
for (const int64_t index : slice.index_range().drop_front(1).drop_back(1)) {
const float dist = dist_to_line_v3(slice[index], slice.first(), slice.last());
for (const int64_t sub_index : sub_range.index_range().drop_front(1).drop_back(1)) {
const float dist = dist_function(sub_range, sub_index);
if (dist > max_dist) {
max_dist = dist;
max_index = index;
max_index = sub_index;
}
}
if (max_dist > epsilon) {
/* Found point outside the epsilon-sized tube. Repeat the search on the left & right side. */
stack.push(IndexRange(range.first(), max_index + 1));
stack.push(IndexRange(range.first() + max_index, range.size() - max_index));
/* Found point outside the epsilon-sized strip. Repeat the search on the left & right side. */
stack.push(sub_range.slice(IndexRange(max_index + 1)));
stack.push(sub_range.slice(IndexRange(max_index, sub_range.size() - max_index)));
}
else {
/* Points in `range` are inside the epsilon-sized tube. Mark them to be deleted. */
points_to_delete.slice(range.drop_front(1).drop_back(1)).fill(true);
/* Points in `sub_range` are inside the epsilon-sized strip. Mark them to be deleted. */
const IndexRange inside_range = sub_range.drop_front(1).drop_back(1);
total_points_to_remove += inside_range.size();
points_to_delete.slice(inside_range).fill(true);
}
}
return total_points_to_remove;
}
static int grease_pencil_stroke_simplify_exec(bContext *C, wmOperator *op)
@@ -466,6 +473,15 @@ static int grease_pencil_stroke_simplify_exec(bContext *C, wmOperator *op)
}
const Span<float3> positions = curves.positions();
/* Distance function for `ramer_douglas_peucker_simplify`. */
auto dist_func = [&](IndexRange range, int64_t index_in_range) {
const Span<float3> position_slice = positions.slice(range);
const float dist_position = dist_to_line_v3(
position_slice[index_in_range], position_slice.first(), position_slice.last());
return dist_position;
};
const VArray<bool> cyclic = curves.cyclic();
const OffsetIndices<int> points_by_curve = curves.points_by_curve();
const VArray<bool> selection = *curves.attributes().lookup_or_default<bool>(
@@ -474,6 +490,7 @@ static int grease_pencil_stroke_simplify_exec(bContext *C, wmOperator *op)
Array<bool> points_to_delete(curves.points_num());
selection.materialize(points_to_delete);
std::atomic<int64_t> total_points_to_delete = 0;
threading::parallel_for(curves.curves_range(), 128, [&](const IndexRange range) {
for (const int curve_i : range) {
const IndexRange points = points_by_curve[curve_i];
@@ -488,13 +505,14 @@ static int grease_pencil_stroke_simplify_exec(bContext *C, wmOperator *op)
const Vector<IndexRange> selection_ranges = array_utils::find_all_ranges(
curve_selection, true);
threading::parallel_for(
selection_ranges.index_range(), 16, [&](const IndexRange range_of_ranges) {
selection_ranges.index_range(), 1024, [&](const IndexRange range_of_ranges) {
for (const IndexRange range : selection_ranges.as_span().slice(range_of_ranges))
{
ramer_douglas_peucker_simplify(
positions.slice(range.shift(points.start())),
total_points_to_delete += ramer_douglas_peucker_simplify(
range.shift(points.start()),
epsilon,
points_to_delete.as_mutable_span().slice(range.shift(points.start())));
dist_func,
points_to_delete.as_mutable_span());
}
});
@@ -504,12 +522,13 @@ static int grease_pencil_stroke_simplify_exec(bContext *C, wmOperator *op)
positions[points.last()], positions[points.last(1)], positions[points.first()]);
if (dist <= epsilon) {
points_to_delete[points.last()] = true;
total_points_to_delete++;
}
}
}
});
if (points_to_delete.as_span().contains(true)) {
if (total_points_to_delete > 0) {
IndexMaskMemory memory;
curves.remove_points(IndexMask::from_bools(points_to_delete, memory));
drawing.tag_topology_changed();

5
source/blender/editors/include/ED_grease_pencil.h
View File

@@ -72,7 +72,10 @@ void gaussian_blur_1D(const GSpan src,
bool is_cyclic,
GMutableSpan dst);
void ramer_douglas_peucker_simplify(const Span<float3> src, float epsilon, MutableSpan<bool> dst);
int64_t ramer_douglas_peucker_simplify(IndexRange range,
float epsilon,
FunctionRef<float(IndexRange, int64_t)> dist_function,
MutableSpan<bool> dst);
} // namespace blender::ed::greasepencil
#endif