From 1130d78c19ffca26ea21632a98640be4f7053a6d Mon Sep 17 00:00:00 2001
From: Lukas Matena <lukasmatena@seznam.cz>
Date: Thu, 29 Oct 2020 12:21:32 +0100
Subject: [PATCH] Fix of #3505 (place on face oriented objects at slight angle
sometimes)
---
src/slic3r/GUI/Selection.cpp | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/src/slic3r/GUI/Selection.cpp b/src/slic3r/GUI/Selection.cpp
index 5547589b9..f7a62a468 100644
--- a/src/slic3r/GUI/Selection.cpp
+++ b/src/slic3r/GUI/Selection.cpp
@@ -853,6 +853,7 @@ void Selection::flattening_rotate(const Vec3d& normal)
// We get the normal in untransformed coordinates. We must transform it using the instance matrix, find out
// how to rotate the instance so it faces downwards and do the rotation. All that for all selected instances.
// The function assumes that is_from_single_object() holds.
+ assert(Slic3r::is_approx(normal.norm(), 1.));
if (!m_valid)
return;
@@ -866,14 +867,31 @@ void Selection::flattening_rotate(const Vec3d& normal)
Vec3d mirror(wmt(0, 0), wmt(1, 1), wmt(2, 2));
Vec3d rotation = Geometry::extract_euler_angles(m_cache.volumes_data[i].get_instance_rotation_matrix());
- Vec3d transformed_normal = Geometry::assemble_transform(Vec3d::Zero(), rotation, scaling_factor, mirror) * normal;
- transformed_normal.normalize();
+ Vec3d tnormal = Geometry::assemble_transform(Vec3d::Zero(), rotation, scaling_factor, mirror) * normal;
+ tnormal.normalize();
- Vec3d axis = transformed_normal(2) > 0.999f ? Vec3d(1., 0., 0.) : Vec3d(transformed_normal.cross(Vec3d(0., 0., -1.)));
+ // Calculate rotation axis. It shall be perpendicular to "down" direction
+ // and the normal, so the rotation is the shortest possible and logical.
+ Vec3d axis = tnormal.cross(-Vec3d::UnitZ());
+
+ // Make sure the axis is not zero and normalize it. "Almost" zero is not interesting.
+ // In case the vectors are almost colinear, the rotation axis does not matter much.
+ if (axis == Vec3d::Zero())
+ axis = Vec3d::UnitX();
axis.normalize();
+ // Calculate the angle using the component where we achieve more precision.
+ // Cosine of small angles is const in first order. No good.
+ double angle = 0.;
+ if (std::abs(tnormal.z()) < std::sqrt(2.)/2.)
+ angle = std::acos(-tnormal.z());
+ else {
+ double xy = std::hypot(tnormal.x(), tnormal.y());
+ angle = PI/2. + std::acos(xy * (tnormal.z() > 0.));
+ }
+
Transform3d extra_rotation = Transform3d::Identity();
- extra_rotation.rotate(Eigen::AngleAxisd(acos(-transformed_normal(2)), axis));
+ extra_rotation.rotate(Eigen::AngleAxisd(angle, axis));
Vec3d new_rotation = Geometry::extract_euler_angles(extra_rotation * m_cache.volumes_data[i].get_instance_rotation_matrix());
(*m_volumes)[i]->set_instance_rotation(new_rotation);