diff options
Diffstat (limited to 'source')
-rw-r--r-- | source/blender/blenkernel/intern/spline_base.cc | 86 |
1 files changed, 84 insertions, 2 deletions
diff --git a/source/blender/blenkernel/intern/spline_base.cc b/source/blender/blenkernel/intern/spline_base.cc index f58d15c06fe..e8294086c35 100644 --- a/source/blender/blenkernel/intern/spline_base.cc +++ b/source/blender/blenkernel/intern/spline_base.cc @@ -227,6 +227,74 @@ static void calculate_normals_z_up(Span<float3> tangents, MutableSpan<float3> r_ } /** + * Rotate the last normal in the same way the tangent has been rotated. + */ +static float3 calculate_next_normal(const float3 &last_normal, + const float3 &last_tangent, + const float3 ¤t_tangent) +{ + if (last_tangent.is_zero() || current_tangent.is_zero()) { + return last_normal; + } + const float angle = angle_normalized_v3v3(last_tangent, current_tangent); + if (angle != 0.0) { + const float3 axis = float3::cross(last_tangent, current_tangent).normalized(); + return rotate_direction_around_axis(last_normal, axis, angle); + } + else { + return last_normal; + } +} + +static void calculate_normals_minimum(Span<float3> tangents, + const bool cyclic, + MutableSpan<float3> r_normals) +{ + BLI_assert(r_normals.size() == tangents.size()); + + if (r_normals.is_empty()) { + return; + } + + const float epsilon = 1e-4f; + + /* Set initial normal. */ + const float3 &first_tangent = tangents[0]; + if (fabs(first_tangent.x) + fabs(first_tangent.y) < epsilon) { + r_normals[0] = {1.0f, 0.0f, 0.0f}; + } + else { + r_normals[0] = float3(first_tangent.y, -first_tangent.x, 0.0f).normalized(); + } + + /* Forward normal with minimum twist along the entire spline. */ + for (const int i : IndexRange(1, r_normals.size() - 1)) { + r_normals[i] = calculate_next_normal(r_normals[i - 1], tangents[i - 1], tangents[i]); + } + + if (!cyclic) { + return; + } + + /* Compute how much the first normal deviates from the normal that has been forwarded along the + * entire cyclic spline. */ + const float3 uncorrected_last_normal = calculate_next_normal( + r_normals.last(), tangents.last(), tangents[0]); + float correction_angle = angle_signed_on_axis_v3v3_v3( + r_normals[0], uncorrected_last_normal, tangents[0]); + if (correction_angle > M_PI) { + correction_angle = correction_angle - 2 * M_PI; + } + + /* Gradually apply correction by rotating all normals slightly. */ + const float angle_step = correction_angle / r_normals.size(); + for (const int i : r_normals.index_range()) { + const float angle = angle_step * i; + r_normals[i] = rotate_direction_around_axis(r_normals[i], tangents[i], angle); + } +} + +/** * Return non-owning access to the direction vectors perpendicular to the tangents at every * evaluated point. The method used to generate the normal vectors depends on Spline.normal_mode. */ @@ -244,11 +312,25 @@ Span<float3> Spline::evaluated_normals() const const int eval_size = this->evaluated_points_size(); evaluated_normals_cache_.resize(eval_size); - Span<float3> tangents = evaluated_tangents(); + Span<float3> tangents = this->evaluated_tangents(); MutableSpan<float3> normals = evaluated_normals_cache_; /* Only Z up normals are supported at the moment. */ - calculate_normals_z_up(tangents, normals); + switch (this->normal_mode) { + case ZUp: { + calculate_normals_z_up(tangents, normals); + break; + } + case Minimum: { + calculate_normals_minimum(tangents, is_cyclic_, normals); + break; + } + case Tangent: { + /* Tangent mode is not yet supported. */ + calculate_normals_z_up(tangents, normals); + break; + } + } /* Rotate the generated normals with the interpolated tilt data. */ GVArray_Typed<float> tilts = this->interpolate_to_evaluated_points(this->tilts()); |