add mesh colorfield visualization support

- visualize_slicer now accepts mesh_colorfield param for vertex/face attribute coloring
- auto-detect vertex vs face attributes, use viridis colormap
- fix HeatGeodesicSolver to accept (V, F) tuple
- update examples to use scalar_field/overhang coloring

closes #179

Author: claude

examples/2_curved_slicing/ex2_curved_slicing.py

@@ -74,7 +74,7 @@ def main(visualize: bool = False):
     print("Total elapsed time", round(end_time - start_time, 2), "seconds")
 
     if visualize:
-        visualize_slicer(slicer, mesh)
+        visualize_slicer(slicer, mesh, mesh_colorfield='scalar_field')
 
 
 if __name__ == "__main__":

examples/6_attributes_transfer/example_6_attributes_transfer.py

@@ -84,7 +84,7 @@ def main(visualize: bool = False):
     utils.save_to_json(utils.point_list_to_dict(direction_to_pt_list), OUTPUT_PATH, 'direction_to_pt_list.json')
 
     if visualize:
-        visualize_slicer(slicer, mesh)
+        visualize_slicer(slicer, mesh, mesh_opacity=0.6, mesh_colorfield='overhang')
 
 
 if __name__ == '__main__':

src/compas_slicer/pre_processing/preprocessing_utils/geodesics.py

@@ -55,7 +55,9 @@ def get_heat_geodesic_distances(
     mesh_hash = hash((len(list(mesh.vertices())), len(list(mesh.faces()))))
     if mesh_hash not in _cgal_solver_cache:
         _cgal_solver_cache.clear()  # Clear old solvers
-        _cgal_solver_cache[mesh_hash] = HeatGeodesicSolver(mesh)
+        V = mesh.vertices_attributes('xyz')
+        F = [mesh.face_vertices(f) for f in mesh.faces()]
+        _cgal_solver_cache[mesh_hash] = HeatGeodesicSolver((V, F))
 
     solver = _cgal_solver_cache[mesh_hash]
 

src/compas_slicer/visualization/visualization.py

@@ -33,6 +33,7 @@ def visualize_slicer(
     mesh: Mesh | None = None,
     show_mesh: bool = True,
     mesh_opacity: float = 0.3,
+    mesh_colorfield: str = "z",
 ) -> None:
     """Visualize slicer toolpaths in compas_viewer.
 
@@ -46,17 +47,33 @@ def visualize_slicer(
         If True, display the mesh.
     mesh_opacity : float
         Opacity for mesh display (0-1).
+    mesh_colorfield : str
+        Vertex attribute name to use for mesh coloring.
 
     """
     from compas.colors import Color
+    from compas.colors import ColorMap
     from compas.geometry import Polyline
     from compas_viewer import Viewer
 
     viewer = Viewer()
 
-    # Add mesh if provided
+    # Add mesh if provided, colored by vertex or face attribute
     if mesh and show_mesh:
-        viewer.scene.add(mesh, opacity=mesh_opacity)
+        cmap = ColorMap.from_mpl("viridis")
+
+        # check if colorfield is vertex or face attribute
+        first_vertex = next(mesh.vertices())
+        if mesh.vertex_attribute(first_vertex, mesh_colorfield) is not None:
+            scalars = {v: mesh.vertex_attribute(v, mesh_colorfield) for v in mesh.vertices()}
+            smin, smax = min(scalars.values()), max(scalars.values())
+            vertexcolor = {v: cmap(s, minval=smin, maxval=smax) for v, s in scalars.items()}
+            viewer.scene.add(mesh, vertexcolor=vertexcolor, opacity=mesh_opacity, use_vertexcolors=True, show_lines=False)
+        else:
+            scalars = {f: mesh.face_attribute(f, mesh_colorfield) for f in mesh.faces()}
+            smin, smax = min(scalars.values()), max(scalars.values())
+            facecolor = {f: cmap(s, minval=smin, maxval=smax) for f, s in scalars.items()}
+            viewer.scene.add(mesh, facecolor=facecolor, opacity=mesh_opacity, show_lines=False)
 
     # Add paths as polylines with color gradient by layer
     n_layers = len(slicer.layers)