Better ThreeDVMobject implementation

mobject/three_d_shading_utils.py

@@ -0,0 +1,56 @@
+import numpy as np
+
+from constants import ORIGIN
+from utils.space_ops import get_unit_normal
+
+
+def get_3d_vmob_gradient_start_and_end_points(vmob):
+    return (
+        get_3d_vmob_start_corner(vmob),
+        get_3d_vmob_end_corner(vmob),
+    )
+
+
+def get_3d_vmob_start_corner_index(vmob):
+    return 0
+
+
+def get_3d_vmob_end_corner_index(vmob):
+    return ((len(vmob.points) - 1) // 6) * 3
+
+
+def get_3d_vmob_start_corner(vmob):
+    if vmob.get_num_points() == 0:
+        return np.array(ORIGIN)
+    return vmob.points[get_3d_vmob_start_corner_index(vmob)]
+
+
+def get_3d_vmob_end_corner(vmob):
+    if vmob.get_num_points() == 0:
+        return np.array(ORIGIN)
+    return vmob.points[get_3d_vmob_end_corner_index(vmob)]
+
+
+def get_3d_vmob_unit_normal(vmob, point_index):
+    n_points = vmob.get_num_points()
+    if vmob.get_num_points() == 0:
+        return np.array(ORIGIN)
+    i = point_index
+    im1 = i - 1 if i > 0 else (n_points - 2)
+    ip1 = i + 1 if i < (n_points - 1) else 1
+    return get_unit_normal(
+        vmob.points[ip1] - vmob.points[i],
+        vmob.points[im1] - vmob.points[i],
+    )
+
+
+def get_3d_vmob_start_corner_unit_normal(vmob):
+    return get_3d_vmob_unit_normal(
+        vmob, get_3d_vmob_start_corner_index(vmob)
+    )
+
+
+def get_3d_vmob_end_corner_unit_normal(vmob):
+    return get_3d_vmob_unit_normal(
+        vmob, get_3d_vmob_end_corner_index(vmob)
+    )