From be9ba936e9b09907409c0f5efa3894ee455a6267 Mon Sep 17 00:00:00 2001
From: Vojtech Kral <vojtech@kral.hk>
Date: Thu, 29 Nov 2018 12:21:42 +0100
Subject: [PATCH] Cut: Sanitize Z when switching selections

---
 src/slic3r/GUI/GLGizmo.cpp | 21 +++++++++++++++++----
 src/slic3r/GUI/GLGizmo.hpp |  6 ++++--
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/slic3r/GUI/GLGizmo.cpp b/src/slic3r/GUI/GLGizmo.cpp
index 348defc42..d15dd3522 100644
--- a/src/slic3r/GUI/GLGizmo.cpp
+++ b/src/slic3r/GUI/GLGizmo.cpp
@@ -2001,6 +2001,7 @@ const std::array<float, 3> GLGizmoCut::GrabberColor = { 1.0, 0.5, 0.0 };
 GLGizmoCut::GLGizmoCut(GLCanvas3D& parent)
     : GLGizmoBase(parent)
     , m_cut_z(0.0)
+    , m_max_z(0.0)
 #if !ENABLE_IMGUI
     , m_panel(nullptr)
 #endif // not ENABLE_IMGUI
@@ -2087,7 +2088,7 @@ void GLGizmoCut::on_start_dragging(const GLCanvas3D::Selection& selection)
 
     const BoundingBoxf3& box = selection.get_bounding_box();
     m_start_z = m_cut_z;
-    m_max_z = box.size()(2);
+    update_max_z(selection);
     m_drag_pos = m_grabbers[m_hover_id].center;
     m_drag_center = box.center();
     m_drag_center(2) = m_cut_z;
@@ -2096,9 +2097,7 @@ void GLGizmoCut::on_start_dragging(const GLCanvas3D::Selection& selection)
 void GLGizmoCut::on_update(const UpdateData& data)
 {
     if (m_hover_id != -1) {
-        // Clamp the plane to the object's bounding box
-        const double new_z = m_start_z + calc_projection(data.mouse_ray);
-        m_cut_z = std::max(0.0, std::min(m_max_z, new_z));
+        set_cut_z(m_start_z + calc_projection(data.mouse_ray));
     }
 }
 
@@ -2108,6 +2107,8 @@ void GLGizmoCut::on_render(const GLCanvas3D::Selection& selection) const
         set_tooltip("Z: " + format(m_cut_z, 2));
     }
 
+    update_max_z(selection);
+
     const BoundingBoxf3& box = selection.get_bounding_box();
     Vec3d plane_center = box.center();
     plane_center(2) = m_cut_z;
@@ -2182,6 +2183,18 @@ void GLGizmoCut::on_render_input_window(float x, float y, const GLCanvas3D::Sele
 }
 #endif // ENABLE_IMGUI
 
+void GLGizmoCut::update_max_z(const GLCanvas3D::Selection& selection) const
+{
+    m_max_z = selection.get_bounding_box().size()(2);
+    set_cut_z(m_cut_z);
+}
+
+void GLGizmoCut::set_cut_z(double cut_z) const
+{
+    // Clamp the plane to the object's bounding box
+    m_cut_z = std::max(0.0, std::min(m_max_z, cut_z));
+}
+
 void GLGizmoCut::perform_cut(const GLCanvas3D::Selection& selection)
 {
     const auto instance_idx = selection.get_instance_idx();
diff --git a/src/slic3r/GUI/GLGizmo.hpp b/src/slic3r/GUI/GLGizmo.hpp
index 198a7cb17..dd8c20946 100644
--- a/src/slic3r/GUI/GLGizmo.hpp
+++ b/src/slic3r/GUI/GLGizmo.hpp
@@ -519,9 +519,9 @@ class GLGizmoCut : public GLGizmoBase
     static const double Margin;
     static const std::array<float, 3> GrabberColor;
 
-    double m_cut_z;
+    mutable double m_cut_z;
     double m_start_z;
-    double m_max_z;
+    mutable double m_max_z;
     Vec3d m_drag_pos;
     Vec3d m_drag_center;
     bool m_keep_upper;
@@ -554,6 +554,8 @@ protected:
     virtual void on_render_input_window(float x, float y, const GLCanvas3D::Selection& selection);
 #endif // ENABLE_IMGUI
 private:
+    void update_max_z(const GLCanvas3D::Selection& selection) const;
+    void set_cut_z(double cut_z) const;
     void perform_cut(const GLCanvas3D::Selection& selection);
     double calc_projection(const Linef3& mouse_ray) const;
 };