From 3aefe3f4132cccc64d21fd7a0ca14eb5967d77f5 Mon Sep 17 00:00:00 2001 From: Mikko Rasa Date: Sun, 5 May 2019 02:16:22 +0300 Subject: [PATCH] Explicitly triangulate faces in the Blender exporter Previously they were implicitly triangulated during strip generation, with the idea that it would be more flexible. However I have some doubts of its benefits and existing strip generation algorithms tend to deal exclusively in triangles. --- blender/io_mspgl/mesh.py | 70 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 67 insertions(+), 3 deletions(-) diff --git a/blender/io_mspgl/mesh.py b/blender/io_mspgl/mesh.py index b58637b7..10c2c214 100644 --- a/blender/io_mspgl/mesh.py +++ b/blender/io_mspgl/mesh.py @@ -9,12 +9,16 @@ class Edge: def __init__(self, edge): if edge.__class__==Edge: self._edge = edge._edge - self.vertices = edge.vertices[:] self.smooth = edge.smooth else: self._edge = edge self.smooth = False - self.key = edge.key + if edge: + self.vertices = edge.vertices[:] + self.key = edge.key + else: + self.vertices = [] + self.key = None self.faces = [] def __getattr__(self, attr): @@ -275,6 +279,64 @@ class Mesh: self.lines += other.lines + def prepare_triangles(self, progress): + face_count = len(self.faces) + for i in range(face_count): + f = self.faces[i] + nverts = len(f.vertices) + if nverts==3: + continue + + # Calculate normals at each vertex of the face + edge_vecs = [] + for j in range(nverts): + edge_vecs.append(f.vertices[(j+1)%nverts].co-f.vertices[j].co) + + normals = [] + for j in range(nverts): + normals.append(edge_vecs[j].cross(edge_vecs[j-1]).normalized()) + + # Check which diagonal results in a flatter triangulation + flatness1 = normals[0].dot(normals[2]) + flatness2 = normals[1].dot(normals[3]) + cut_index = 1 if flatness1>flatness2 else 0 + + nf = Face(f) + nf.index = len(self.faces) + self.faces.append(nf) + + ne = Edge(None) + ne.index = len(self.edges) + self.edges.append(ne) + + nf.vertices = [f.vertices[cut_index], f.vertices[2], f.vertices[3]] + nf.loop_indices = [f.loop_indices[cut_index], f.loop_indices[2], f.loop_indices[3]] + for v in nf.vertices: + v.faces.append(nf) + + ne.vertices = [f.vertices[cut_index], f.vertices[2+cut_index]] + for v in ne.vertices: + v.edges.append(ne) + ne.key = make_edge_key(ne.vertices[0].index, ne.vertices[1].index) + ne.smooth = True + + f.vertices[3-cut_index].faces.remove(f) + del f.vertices[3-cut_index] + f.loop_indices = [f.loop_indices[0], f.loop_indices[1], f.loop_indices[2+cut_index]] + + ne.faces = [f, nf] + if cut_index==0: + nf.edges = [ne, f.edges[2], f.edges[3]] + f.edges = [f.edges[0], f.edges[1], ne] + else: + nf.edges = [f.edges[1], f.edges[2], ne] + f.edges = [f.edges[0], ne, f.edges[3]] + + f.normal = normals[1-cut_index] + nf.normal = normals[3-cut_index] + + progress.set_progress(i/face_count) + def prepare_smoothing(self, progress): smooth_limit = -1 if self.smoothing=='NONE': @@ -594,7 +656,7 @@ def create_mesh_from_object(context, obj, progress): if obj.type!="MESH": raise Exception("Object is not a mesh") - progress.push_task("Preparing mesh", 0.0, 0.3) + progress.push_task("Preparing mesh", 0.0, 0.2) objs = [(obj, mathutils.Matrix())] i = 0 @@ -629,6 +691,8 @@ def create_mesh_from_object(context, obj, progress): else: mesh = me + progress.set_task("Triangulating", 0.2, 0.3) + mesh.prepare_triangles(progress) progress.set_task("Smoothing", 0.3, 0.6) mesh.prepare_smoothing(progress) progress.set_task("Vertex groups", 0.6, 0.7) -- 2.45.2