FDM supports gizmo 'autoset by angle' improvements:

- Extra dialog for autosetting by angle in FDM supports gizmo was removed
- Highlighting facets by angle is now controlled by a slider in the main gizmo dialog
- User is allowed to paint even when using the slope highlighter
- The button to turn highlighted facets to blockers was removed, it made no sense
- Highlighted facets are now rendered in light blue

resources/shaders/gouraud.fs

@@ -32,22 +32,22 @@ varying vec3 delta_box_max;
 varying float world_normal_z;
 varying vec3 eye_normal;
 
-vec3 slope_color()
-{
-    return (world_normal_z > slope.normal_z - EPSILON) ? GREEN : RED;
-}
-
 void main()
 {
     if (any(lessThan(clipping_planes_dots, ZERO)))
         discard;
-	vec3 color = slope.actived ? slope_color() : uniform_color.rgb;
+    vec3 color = uniform_color.rgb;
+    float alpha = uniform_color.a;
+    if (slope.actived && world_normal_z < slope.normal_z - EPSILON) {
+        color = vec3(0.7f, 0.7f, 1.f);
+        alpha = 1.f;
+    }
     // if the fragment is outside the print volume -> use darker color
 	color = (any(lessThan(delta_box_min, ZERO)) || any(greaterThan(delta_box_max, ZERO))) ? mix(color, ZERO, 0.3333) : color;
 #ifdef ENABLE_ENVIRONMENT_MAP
     if (use_environment_tex)
-        gl_FragColor = vec4(0.45 * texture2D(environment_tex, normalize(eye_normal).xy * 0.5 + 0.5).xyz + 0.8 * color * intensity.x, uniform_color.a);
+        gl_FragColor = vec4(0.45 * texture2D(environment_tex, normalize(eye_normal).xy * 0.5 + 0.5).xyz + 0.8 * color * intensity.x, alpha);
     else
 #endif
-        gl_FragColor = vec4(vec3(intensity.y) + color * intensity.x, uniform_color.a);
+        gl_FragColor = vec4(vec3(intensity.y) + color * intensity.x, alpha);
 }

src/libslic3r/TriangleSelector.cpp

@@ -425,8 +425,11 @@ void TriangleSelector::reset()
     m_triangles.clear();
     for (const stl_vertex& vert : m_mesh->its.vertices)
         m_vertices.emplace_back(vert);
-    for (const stl_triangle_vertex_indices& ind : m_mesh->its.indices)
-        push_triangle(ind[0], ind[1], ind[2]);
+    for (size_t i=0; i<m_mesh->its.indices.size(); ++i) {
+        const stl_triangle_vertex_indices& ind = m_mesh->its.indices[i];
+        const Vec3f& normal = m_mesh->stl.facet_start[i].normal;
+        push_triangle(ind[0], ind[1], ind[2], normal);
+    }
     m_orig_size_vertices = m_vertices.size();
     m_orig_size_indices = m_triangles.size();
     m_invalid_triangles = 0;
@@ -451,19 +454,20 @@ void TriangleSelector::set_edge_limit(float edge_limit)
 
 
 
-void TriangleSelector::push_triangle(int a, int b, int c)
+void TriangleSelector::push_triangle(int a, int b, int c, const Vec3f& normal)
 {
     for (int i : {a, b, c}) {
         assert(i >= 0 && i < int(m_vertices.size()));
         ++m_vertices[i].ref_cnt;
     }
-    m_triangles.emplace_back(a, b, c);
+    m_triangles.emplace_back(a, b, c, normal);
 }
 
 
 void TriangleSelector::perform_split(int facet_idx, EnforcerBlockerType old_state)
 {
     Triangle* tr = &m_triangles[facet_idx];
+    const Vec3f normal = tr->normal;
 
     assert(tr->is_split());
 
@@ -483,8 +487,8 @@ void TriangleSelector::perform_split(int facet_idx, EnforcerBlockerType old_stat
         m_vertices.emplace_back((m_vertices[verts_idxs[1]].v + m_vertices[verts_idxs[2]].v)/2.);
         verts_idxs.insert(verts_idxs.begin()+2, m_vertices.size() - 1);
 
-        push_triangle(verts_idxs[0], verts_idxs[1], verts_idxs[2]);
-        push_triangle(verts_idxs[2], verts_idxs[3], verts_idxs[0]);
+        push_triangle(verts_idxs[0], verts_idxs[1], verts_idxs[2], normal);
+        push_triangle(verts_idxs[2], verts_idxs[3], verts_idxs[0], normal);
     }
 
     if (sides_to_split == 2) {
@@ -494,9 +498,9 @@ void TriangleSelector::perform_split(int facet_idx, EnforcerBlockerType old_stat
         m_vertices.emplace_back((m_vertices[verts_idxs[0]].v + m_vertices[verts_idxs[3]].v)/2.);
         verts_idxs.insert(verts_idxs.begin()+4, m_vertices.size() - 1);
 
-        push_triangle(verts_idxs[0], verts_idxs[1], verts_idxs[4]);
-        push_triangle(verts_idxs[1], verts_idxs[2], verts_idxs[4]);
-        push_triangle(verts_idxs[2], verts_idxs[3], verts_idxs[4]);
+        push_triangle(verts_idxs[0], verts_idxs[1], verts_idxs[4], normal);
+        push_triangle(verts_idxs[1], verts_idxs[2], verts_idxs[4], normal);
+        push_triangle(verts_idxs[2], verts_idxs[3], verts_idxs[4], normal);
     }
 
     if (sides_to_split == 3) {
@@ -507,10 +511,10 @@ void TriangleSelector::perform_split(int facet_idx, EnforcerBlockerType old_stat
         m_vertices.emplace_back((m_vertices[verts_idxs[4]].v + m_vertices[verts_idxs[0]].v)/2.);
         verts_idxs.insert(verts_idxs.begin()+5, m_vertices.size() - 1);
 
-        push_triangle(verts_idxs[0], verts_idxs[1], verts_idxs[5]);
-        push_triangle(verts_idxs[1], verts_idxs[2], verts_idxs[3]);
-        push_triangle(verts_idxs[3], verts_idxs[4], verts_idxs[5]);
-        push_triangle(verts_idxs[1], verts_idxs[3], verts_idxs[5]);
+        push_triangle(verts_idxs[0], verts_idxs[1], verts_idxs[5], normal);
+        push_triangle(verts_idxs[1], verts_idxs[2], verts_idxs[3], normal);
+        push_triangle(verts_idxs[3], verts_idxs[4], verts_idxs[5], normal);
+        push_triangle(verts_idxs[1], verts_idxs[3], verts_idxs[5], normal);
     }
 
     tr = &m_triangles[facet_idx]; // may have been invalidated

src/libslic3r/TriangleSelector.hpp

@@ -63,8 +63,9 @@ class TriangleSelector {
     public:
         // Use TriangleSelector::push_triangle to create a new triangle.
         // It increments/decrements reference counter on vertices.
-        Triangle(int a, int b, int c)
+        Triangle(int a, int b, int c, const Vec3f& normal_)
             : verts_idxs{a, b, c},
+              normal{normal_},
               state{EnforcerBlockerType(0)},
               number_of_splits{0},
               special_side_idx{0},
@@ -73,6 +74,9 @@ class TriangleSelector {
         // Indices into m_vertices.
         std::array<int, 3> verts_idxs;
 
+        // Triangle normal (a shader might need it).
+        Vec3f normal;
+
         // Is this triangle valid or marked to be removed?
         bool valid{true};
 
@@ -158,7 +162,7 @@ class TriangleSelector {
     void remove_useless_children(int facet_idx); // No hidden meaning. Triangles are meant.
     bool is_pointer_in_triangle(int facet_idx) const;
     bool is_edge_inside_cursor(int facet_idx) const;
-    void push_triangle(int a, int b, int c);
+    void push_triangle(int a, int b, int c, const Vec3f& normal);
     void perform_split(int facet_idx, EnforcerBlockerType old_state);
 };