Many changes; started refactor in gmtypes2.py

gradientmesh/gmtypes2.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+from __future__ import annotations
+from typing import TypeAlias
+from random import uniform
+
+import torch
+
+Point: TypeAlias = torch.FloatTensor
+Vector: TypeAlias = Point
+Color: TypeAlias = torch.FloatTensor
+
+
+def indexize_tensor(tensor, eps=1e-5):
+    """Take tensor of quads to flat list of points plus index map."""
+    tensor_shape = tensor.shape
+    tensor = tensor.view(-1, tensor_shape[-1])
+
+    # Round tensor elements to handle floating point precision errors
+    tensor = torch.round(tensor / eps) * eps
+
+    # Compute unique rows and their indices
+    tensor, inverse_indices = tensor.unique(dim=0, return_inverse=True)
+
+    # Compute index tensor
+    index_tensor = inverse_indices.view(tensor_shape[:-1])
+
+    return tensor, index_tensor
+
+
+def ferguson_to_bezier(corner_points, tangent_vectors):
+    """Take Ferguson patch to Bezier representation"""
+    # Assume corner_points is a list of 4 points [P0, P1, P2, P3] and
+    # tangent_vectors is a list of 4 vectors [V0, V1, V2, V3]
+
+    # Bezier control points
+    bezier_points = [None]*12
+
+    # Use tangent vectors to determine interior points and place them in the order
+    for i in range(4):
+        bezier_points[3*i] = corner_points[i]
+        bezier_points[3*i + 1] = corner_points[i] + tangent_vectors[i]/3
+        bezier_points[3*i + 2] = corner_points[i] + 2*tangent_vectors[i]/3
+
+    return bezier_points
+
+
+class Mesh:
+    def __init__(self, points, tangents, colors):
+        self.fpoints, self.ipoints = indexize_tensor(points)
+        self.ftangents, self.itangents = indexize_tensor(tangents)
+        self.colors = colors
+
+    @classmethod
+    def grid(cls, width, height):
+        dx = 1.0 / width
+        dy = 1.0 / height
+        points = []
+        tangents = []
+        colors = []
+        for i in range(width):
+            for j in range(height):
+                x1, y1 = i * dx, j * dy
+                x2, y2 = (i+1) * dx, (j+1) * dy
+                # Clockwise order: bottom left, bottom right, top right, top left
+                square = [[x1, y1], [x2, y1], [x2, y2], [x1, y2]]
+                points.append(square)
+                tangents.append([[0.0, 0.0] for _ in range(4)])
+                colors.append([uniform(0, 1) for _ in range(3)] + [1.0])
+
+        return cls(torch.tensor(points),
+                   torch.tensor(tangents),
+                   torch.tensor(colors))