Add alternative backe pipeline

src/libslic3r/TextureBake/TextureBakeRepair.hpp

@@ -0,0 +1,48 @@
+#pragma once
+
+// T-junction resolution and edge-defect accounting.
+//
+// Decimation can collapse a long edge whose interior still carries neighbouring triangles' vertices.
+// Those then sit *on* an edge rather than at an end: watertight vertex-for-vertex, but the edge has
+// one incident face on one side, which a slicer reads as an open boundary. This splits the offending
+// face into a fan so every on-edge vertex becomes a real corner.
+
+#include <cstdint>
+#include <vector>
+
+#include "TextureBakeIndex.hpp"
+
+namespace Slic3r {
+namespace TextureBake {
+
+struct EdgeDefects
+{
+    size_t open = 0, non_manifold = 0, triangles = 0;
+};
+
+// Welds at the export grid first: counting on the un-snapped mesh reports defects the file does not
+// have and misses ones it does.
+EdgeDefects count_edge_defects(const TriSoup &geometry, double quant = WELD_GRID_EXPORT);
+
+// Triangles a slicer would drop as degenerate. Each one, removed, punches a hole - so a non-zero
+// count means watertight only on paper.
+size_t count_area_slivers(const TriSoup &geometry);
+
+struct RepairOptions
+{
+    // Coordinates are snapped onto this grid, matching the precision files are written with.
+    double weld_quant = WELD_GRID_EXPORT;
+
+    // How far off an edge a vertex may sit and still count as on it. Well above the harvest
+    // tolerance, since harvesting leaves a region flat only to within that, making a collapsed edge a
+    // chord the on-edge vertices deviate from by about as much. Still far below the weld grid.
+    double on_seg_tol = 0.02;
+
+    // Splitting one face can expose another behind it, so the pass cascades.
+    int max_iters = 16;
+};
+
+TriSoup resolve_t_junctions(const TriSoup &geometry, const RepairOptions &opts = {});
+
+} // namespace TextureBake
+} // namespace Slic3r