Add quadric edge collapse

src/libslic3r/QuadricEdgeCollapse.hpp

@@ -0,0 +1,17 @@
+// paper: https://people.eecs.berkeley.edu/~jrs/meshpapers/GarlandHeckbert2.pdf
+// sum up: https://users.csc.calpoly.edu/~zwood/teaching/csc570/final06/jseeba/
+// inspiration: https://github.com/sp4cerat/Fast-Quadric-Mesh-Simplification
+
+#include "TriangleMesh.hpp"
+
+namespace Slic3r {
+
+/// <summary>
+/// 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);
+
+} // namespace Slic3r