Remap filament for pre-colored models (#10303)

* Add a new feature to allow users to remap filament for a pre-painted model.

* Fix the color issues to support the theme

* clean up code

* Fix broken freetype-2.12.1.tar.gz link

src/libslic3r/TriangleSelector.hpp

@@ -37,6 +37,9 @@ enum class EnforcerBlockerType : int8_t {
     ExtruderMax = Extruder16
 };
 
+// Type alias for the state mapping array to improve code readability
+using EnforcerBlockerStateMap = std::array<EnforcerBlockerType, (size_t)EnforcerBlockerType::ExtruderMax + 1>;
+
 // Following class holds information about selected triangles. It also has power
 // to recursively subdivide the triangles and make the selection finer.
 class TriangleSelector
@@ -344,6 +347,10 @@ public:
     // Remove all unnecessary data.
     void garbage_collect();
 
+    // Orca: remap the state of triangles according to the state_map
+    void remap_triangle_state(const EnforcerBlockerStateMap& state_map);
+
+
     // Store the division trees in compact form (a long stream of bits for each triangle of the original mesh).
     // First vector contains pairs of (triangle index, first bit in the second vector).
     TriangleSplittingData serialize() const;
@@ -416,10 +423,17 @@ protected:
         // or index of a vertex shared by the two split edges (for number_of_splits == 2).
         // For number_of_splits == 3, special_side_idx is always zero.
         char special_side_idx { 0 };
-        EnforcerBlockerType state;
         bool m_selected_by_seed_fill : 1;
         // Is this triangle valid or marked to be removed?
         bool m_valid : 1;
+
+        // Orca:
+        // IMPORTANT: `state` is intentionally placed after all other small members
+        // to prevent compilers from packing it in a way that would create
+        // data races during parallel processing. A write to `state` could
+        // otherwise become a non-atomic read-modify-write on a memory word
+        // that also contains other (bit-field) members, causing race conditions.
+        EnforcerBlockerType state;
     };
 
     struct Vertex {