ADD-FIX curvature examples and environment.yml

Author: petrasvestartas

docs/examples/curvature.py

@@ -0,0 +1,89 @@
+import compas
+import numpy as np
+import compas_libigl as igl
+from compas.colors import Color
+from compas.colors.colormap import ColorMap
+from compas.datastructures import Mesh
+from compas.geometry import Point, Line, Vector
+from compas_viewer import Viewer
+from compas_viewer.scene import BufferGeometry
+
+# ==============================================================================
+# Input geometry
+# ==============================================================================
+
+mesh = Mesh.from_obj(compas.get("tubemesh.obj"))
+trimesh = mesh.copy()
+trimesh.quads_to_triangles()
+
+# ==============================================================================
+# Gaussian Curvature
+# ==============================================================================
+
+vertices, faces = trimesh.to_vertices_and_faces()
+gaussian_curvature = igl.trimesh_gaussian_curvature((vertices, faces))
+
+# Get non-boundary vertex indices
+non_boundary_vertices = [i for i in range(len(vertices)) if not trimesh.is_vertex_on_boundary(i)]
+
+# Prepare vertex colors based on Gaussian curvature (excluding boundary vertices)
+min_gaussian = min(gaussian_curvature[i] for i in non_boundary_vertices)
+max_gaussian = max(gaussian_curvature[i] for i in non_boundary_vertices)
+print(f"Gaussian curvature range: {min_gaussian:.3f} to {max_gaussian:.3f}")
+
+# Scale factor for normal vectors
+normal_scale = -10
+
+# Create two-color maps for negative and positive curvature
+cmap_negative = ColorMap.from_two_colors(Color.blue(), Color.yellow())
+cmap_positive = ColorMap.from_two_colors(Color.yellow(), Color.magenta())
+
+# Convert mesh to numpy arrays for BufferGeometry
+vertices = np.array(vertices, dtype=np.float32)
+faces = np.array(faces, dtype=np.float32)
+
+# Create vertex colors array (Nx4 for RGBA)
+vertex_colors = np.zeros((len(vertices), 4), dtype=np.float32)
+for i, k in enumerate(gaussian_curvature):
+    if trimesh.is_vertex_on_boundary(i):
+        # Set boundary vertices to a neutral color
+        vertex_colors[i] = [0, 0, 0, 1.0]
+    else:
+        if k < 0:
+            color = cmap_negative(k, minval=min_gaussian, maxval=0)
+        else:
+            color = cmap_positive(k, minval=0, maxval=max_gaussian)
+        vertex_colors[i] = (color[0], color[1], color[2], 1.0)
+
+# Create geometry for the mesh with vertex colors
+faces_for_buffer = np.array([vertices[f] for f in faces.astype(int)]).reshape(-1, 3)
+vertex_colors_for_buffer = np.array([vertex_colors[i] for i in faces.astype(int)]).reshape(-1, 4)
+
+geometry = BufferGeometry(
+    faces=faces_for_buffer,
+    facecolor=vertex_colors_for_buffer
+)
+
+# ==============================================================================
+# Visualization
+# ==============================================================================
+
+viewer = Viewer()
+viewer.scene.add(geometry)
+
+# Add normal vectors colored by Gaussian curvature
+for vertex_idx, point in enumerate(vertices):
+    if not trimesh.is_vertex_on_boundary(vertex_idx):
+        point = Point(*point)
+        normal = Vector(*trimesh.vertex_normal(vertex_idx))
+        k = gaussian_curvature[vertex_idx]
+        
+        # Scale normal by absolute curvature value
+        scaled_normal = normal.scaled(normal_scale * k)
+        
+        viewer.scene.add(
+            Line(point, point + scaled_normal),
+            linecolor=Color.black(),
+            linewidth=2
+        )
+viewer.show()

docs/examples/curvature_gaussian.py

@@ -0,0 +1,61 @@
+import compas
+import numpy as np
+import compas_libigl as igl
+from compas.colors import Color
+from compas.colors.colormap import ColorMap
+from compas.datastructures import Mesh
+from compas.geometry import Line, Point, Vector
+from compas_viewer import Viewer
+from compas_viewer.scene import BufferGeometry
+
+# ==============================================================================
+# Input geometry
+# ==============================================================================
+
+mesh = Mesh.from_obj(compas.get("tubemesh.obj"))
+trimesh = mesh.copy()
+trimesh.quads_to_triangles()
+
+# ==============================================================================
+# Principal Curvature
+# ==============================================================================
+
+vertices, faces = trimesh.to_vertices_and_faces()
+PD1, PD2, PV1, PV2 = igl.trimesh_principal_curvature((vertices, faces))
+
+# ==============================================================================
+# Visualization
+# ==============================================================================
+
+viewer = Viewer()
+
+# Add the colored mesh
+viewer.scene.add(mesh)
+
+# Scale factor for principal direction lines
+principal_scale = 0.3
+
+# Add principal direction lines
+for vertex_idx, point in enumerate(vertices):
+    if not trimesh.is_vertex_on_boundary(vertex_idx):
+        point = Point(*point)
+        
+        # Scale lines by curvature magnitude
+        pd1 = Vector(*PD1[vertex_idx]).scaled(principal_scale * abs(PV1[vertex_idx]))
+        pd2 = Vector(*PD2[vertex_idx]).scaled(principal_scale * abs(PV2[vertex_idx]))
+        
+        # Maximum principal direction (black)
+        viewer.scene.add(
+            Line(point - pd1, point + pd1),
+            linecolor=Color.black(),
+            linewidth=2
+        )
+        # Minimum principal direction (black)
+        viewer.scene.add(
+            Line(point - pd2, point + pd2),
+            linecolor=Color.black(),
+            linewidth=2
+        )
+
+
+viewer.show()

docs/examples/curvature_principal.py

@@ -6,5 +6,6 @@ dependencies:
   - git
   - cmake>=3.14
   - compas
+  - invoke
   - pip:
       - -e .[dev]