Speed up QEC by move error directly into MutablePriorityQueue

Memory optimization: Change size_t to 32bit int
Lightweight Error structure for faster PriorityQueue

src/libslic3r/QuadricEdgeCollapse.hpp

@@ -2,6 +2,7 @@
 // sum up: https://users.csc.calpoly.edu/~zwood/teaching/csc570/final06/jseeba/
 // inspiration: https://github.com/sp4cerat/Fast-Quadric-Mesh-Simplification
 
+#include <cstdint>
 #include "TriangleMesh.hpp"
 
 namespace Slic3r {
@@ -10,8 +11,13 @@ namespace Slic3r {
 /// Simplify mesh by Quadric metric
 /// </summary>
 /// <param name="its">IN/OUT triangle mesh to be simplified.</param>
-/// <param name="triangle_count">wanted triangle count.</param>
-/// <returns>TRUE on success otherwise FALSE</returns>
-bool its_quadric_edge_collapse(indexed_triangle_set &its, size_t triangle_count);
+/// <param name="triangle_count">Wanted triangle count.</param>
+/// <param name="max_error">Maximal Quadric for reduce.
+/// When nullptr then max float is used
+/// Output: Last used ErrorValue to collapse edge
+/// </param>
+void its_quadric_edge_collapse(indexed_triangle_set &its,
+                               uint32_t              triangle_count = 0,
+                               float *               max_error = nullptr);
 
 } // namespace Slic3r