From 093074aefe87259882b56a911d8eeb311408ff14 Mon Sep 17 00:00:00 2001 From: Hans Goudey Date: Wed, 14 Jul 2021 15:13:17 -0400 Subject: Bezier Spline: Add a more generalized insertion utility This logic is from the curve sundivide node, used to add points with proper handles in between two existing points. However, the same logic is used for trimming of Bezier splines, and possibly interactive point insertion in the future, so it's helpful as a general utility. The logic is converted to depend on a bezier spline instead of being static. A temporary segment spline can be used for the latter use case. --- .../geometry/nodes/node_geo_curve_subdivide.cc | 76 +++++++++------------- 1 file changed, 32 insertions(+), 44 deletions(-) (limited to 'source/blender/nodes') diff --git a/source/blender/nodes/geometry/nodes/node_geo_curve_subdivide.cc b/source/blender/nodes/geometry/nodes/node_geo_curve_subdivide.cc index 3de2604cd0a..7908c26e2dc 100644 --- a/source/blender/nodes/geometry/nodes/node_geo_curve_subdivide.cc +++ b/source/blender/nodes/geometry/nodes/node_geo_curve_subdivide.cc @@ -115,38 +115,6 @@ static void subdivide_attribute(Span src, } } -/** - * De Casteljau Bezier subdivision. - * - * 
- *           handle_prev         handle_next
- *                O----------------O
- *               /                  \
- *              /      x---O---x     \
- *             /         new_*        \
- *            /                        \
- *           O                          O
- *       point_prev                  point_next
- *
- */ -static void calculate_new_bezier_point(const float3 &point_prev, - float3 &handle_prev, - float3 &new_left_handle, - float3 &new_position, - float3 &new_right_handle, - float3 &handle_next, - const float3 &point_next, - const float parameter) -{ - const float3 center_point = float3::interpolate(handle_prev, handle_next, parameter); - - handle_prev = float3::interpolate(point_prev, handle_prev, parameter); - handle_next = float3::interpolate(handle_next, point_next, parameter); - new_left_handle = float3::interpolate(handle_prev, center_point, parameter); - new_right_handle = float3::interpolate(center_point, handle_next, parameter); - new_position = float3::interpolate(new_left_handle, new_right_handle, parameter); -} - /** * In order to generate a Bezier spline with the same shape as the input spline, apply the * De Casteljau algorithm iteratively for the provided number of cuts, constantly updating the @@ -171,6 +139,10 @@ static void subdivide_bezier_segment(const BezierSpline &src, { const bool is_last_cyclic_segment = index == (src.size() - 1); const int next_index = is_last_cyclic_segment ? 0 : index + 1; + + /* The first point in the segment is always copied. */ + dst_positions[offset] = src_positions[index]; + if (src.segment_is_vector(index)) { if (is_last_cyclic_segment) { dst_type_left.first() = BezierSpline::HandleType::Vector; @@ -178,7 +150,6 @@ static void subdivide_bezier_segment(const BezierSpline &src, dst_type_left.slice(offset + 1, result_size).fill(BezierSpline::HandleType::Vector); dst_type_right.slice(offset, result_size).fill(BezierSpline::HandleType::Vector); - dst_positions[offset] = src_positions[index]; const float factor_delta = 1.0f / result_size; for (const int cut : IndexRange(result_size)) { const float factor = cut * factor_delta; @@ -194,21 +165,38 @@ static void subdivide_bezier_segment(const BezierSpline &src, dst_type_right.slice(offset, result_size).fill(BezierSpline::HandleType::Free); const int i_segment_last = is_last_cyclic_segment ? 0 : offset + result_size; - dst_positions[offset] = src_positions[index]; - dst_handles_right[offset] = src_handles_right[index]; - dst_handles_left[i_segment_last] = src_handles_left[next_index]; + + /* Create a Bezier segment to update iteratively for every subdivision + * and references to the meaningful values for ease of use. */ + BezierSpline temp; + temp.resize(2); + float3 &segment_start = temp.positions().first(); + float3 &segment_end = temp.positions().last(); + float3 &handle_prev = temp.handle_positions_right().first(); + float3 &handle_next = temp.handle_positions_left().last(); + segment_start = src_positions[index]; + segment_end = src_positions[next_index]; + handle_prev = src_handles_right[index]; + handle_next = src_handles_left[next_index]; for (const int cut : IndexRange(result_size - 1)) { const float parameter = 1.0f / (result_size - cut); - calculate_new_bezier_point(dst_positions[offset + cut], - dst_handles_right[offset + cut], - dst_handles_left[offset + cut + 1], - dst_positions[offset + cut + 1], - dst_handles_right[offset + cut + 1], - dst_handles_left[i_segment_last], - src_positions[next_index], - parameter); + const BezierSpline::InsertResult insert = temp.calculate_segment_insertion(0, 1, parameter); + + /* Copy relevant temporary data to the result. */ + dst_handles_right[offset + cut] = insert.handle_prev; + dst_handles_left[offset + cut + 1] = insert.left_handle; + dst_positions[offset + cut + 1] = insert.position; + + /* Update the segment to prepare it for the next subdivision. */ + segment_start = insert.position; + handle_prev = insert.right_handle; + handle_next = insert.handle_next; } + + /* Copy the handles for the last segment from the temporary spline. */ + dst_handles_right[offset + result_size - 1] = handle_prev; + dst_handles_left[i_segment_last] = handle_next; } } -- cgit v1.2.3