82 lines
2.6 KiB
Python
82 lines
2.6 KiB
Python
""" Contains triangle strip generation functions for GeometrySegment. """
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from typing import List, Tuple
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from copy import deepcopy
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from .msh_model import *
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def create_models_triangle_strips(models: List[Model]) -> List[Model]:
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""" Create the triangle strips for a list of models geometry. """
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for model in models:
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if model.geometry is not None:
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for segment in model.geometry:
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segment.triangle_strips = create_triangle_strips(segment.triangles)
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return models
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def create_triangle_strips(segment_triangles: List[List[int]]) -> List[List[int]]:
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""" Create the triangle strips for a list of triangles. """
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triangles = deepcopy(segment_triangles)
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strips: List[List[int]] = []
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# The general idea here is we loop based off if 'triangles' is empty or not.
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#
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# For each iteration of the loop we create a new strip starting from the first
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# triangle still in 'triangles'.
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#
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# Then we loop, attempting to find a triangle to add the strip each time. If we
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# find one then we continue the loop, else we break out of it and append the
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# created strip.
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def create_strip() -> List[int]:
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strip: List[int] = [triangles[0][0],
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triangles[0][1],
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triangles[0][2]]
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strip_head: Tuple[int, int] = (strip[1], strip[2])
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triangles.remove(triangles[0])
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while True:
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def find_next_vertex():
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nonlocal triangles
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even: bool = len(strip) % 2 == 0
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for tri, edge, last_vertex in iterate_triangle_edges_last_vertex(triangles, even):
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if edge == strip_head:
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triangles.remove(tri)
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return last_vertex
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return None
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next_vertex: int = find_next_vertex()
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if next_vertex is None:
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break
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strip.append(next_vertex)
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strip_head = (strip_head[1], next_vertex)
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return strip
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while triangles:
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strips.append(create_strip())
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return strips
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def iterate_triangle_edges_last_vertex(triangles: List[List[int]], even: bool):
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""" Generator for iterating through the of each triangle in a list edges.
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Yields (triangle, edge, last_vertex). """
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if even:
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for tri in triangles:
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yield tri, (tri[0], tri[1]), tri[2]
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yield tri, (tri[0], tri[2]), tri[1]
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yield tri, (tri[1], tri[2]), tri[0]
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else:
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for tri in triangles:
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yield tri, (tri[1], tri[0]), tri[2]
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yield tri, (tri[2], tri[0]), tri[1]
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yield tri, (tri[2], tri[1]), tri[0]
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