source: OniSplit/Akira/OctreeNode.cs@ 1125

Last change on this file since 1125 was 1114, checked in by iritscen, 5 years ago

Adding OniSplit source code (v0.9.99.0). Many thanks to Neo for all his work over the years.
File size: 14.4 KB
RevLine 
[1114]1using System;
2using System.Collections.Generic;
3
4namespace Oni.Akira
5{
6 internal class OctreeNode
7 {
8 public const int FaceCount = 6;
9 public const int ChildCount = 8;
10
11 private const float MinNodeSize = 16.0f;
12 private const int MaxQuadsPerLeaf = 4096;
13 private const int MaxRoomsPerLeaf = 255;
14
15 #region Private data
16 private int index;
17 private BoundingBox bbox;
18 private Polygon[] polygons;
19 private OctreeNode[] children;
20 private OctreeNode[] adjacency = new OctreeNode[FaceCount];
21 private Room[] rooms;
22 #endregion
23
24 #region public enum Axis
25
26 public enum Axis
27 {
28 Z,
29 Y,
30 X
31 }
32
33 #endregion
34 #region public enum Direction
35
36 public enum Direction
37 {
38 Negative,
39 Positive
40 }
41
42 #endregion
43 #region public struct Face
44
45 public struct Face
46 {
47 private readonly int index;
48
49 public Face(int index)
50 {
51 this.index = index;
52 }
53
54 public int Index => index;
55 public Axis Axis => (Axis)(2 - ((index & 6) >> 1));
56 public Direction Direction => (Direction)(index & 1);
57
58 public static IEnumerable<Face> All
59 {
60 get
61 {
62 for (int i = 0; i < FaceCount; i++)
63 yield return new Face(i);
64 }
65 }
66 }
67
68 #endregion
69 #region public struct ChildPosition
70
71 public struct ChildPosition
72 {
73 private int index;
74
75 public ChildPosition(int index)
76 {
77 this.index = index;
78 }
79
80 public int Index => index;
81
82 public int X => this[Axis.X];
83 public int Y => this[Axis.Y];
84 public int Z => this[Axis.Z];
85
86 public int this[Axis axis]
87 {
88 get
89 {
90 return ((index >> (int)axis) & 1);
91 }
92 set
93 {
94 int mask = (1 << (int)axis);
95
96 if (value == 0)
97 index &= ~mask;
98 else
99 index |= mask;
100 }
101 }
102
103 public static IEnumerable<ChildPosition> All
104 {
105 get
106 {
107 for (int i = 0; i < 8; i++)
108 yield return new ChildPosition(i);
109 }
110 }
111 }
112
113 #endregion
114
115 public OctreeNode(BoundingBox bbox, IEnumerable<Polygon> polygons, IEnumerable<Room> rooms)
116 {
117 this.bbox = bbox;
118 this.polygons = polygons.ToArray();
119 this.rooms = rooms.ToArray();
120 }
121
122 private OctreeNode(BoundingBox bbox, Polygon[] polygons, Room[] rooms)
123 {
124 this.bbox = bbox;
125 this.polygons = polygons;
126 this.rooms = rooms;
127 }
128
129 public int Index
130 {
131 get { return index; }
132 set { index = value; }
133 }
134
135 public BoundingBox BoundingBox => bbox;
136 public OctreeNode[] Children => children;
137 public OctreeNode[] Adjacency => adjacency;
138 public bool IsLeaf => polygons != null;
139 public ICollection<Polygon> Polygons => polygons;
140 public ICollection<Room> Rooms => rooms;
141 private Vector3 Center => (bbox.Min + bbox.Max) * 0.5f;
142 private float Size => bbox.Max.X - bbox.Min.X;
143
144 public void Build()
145 {
146 BuildRecursive();
147
148 //
149 // Force a split of the root node because the root cannot be a leaf.
150 //
151
152 if (children == null)
153 Split();
154 }
155
156 private void BuildRecursive()
157 {
158 if ((polygons == null || polygons.Length <= 19) && (rooms == null || rooms.Length < 16))
159 {
160 return;
161 }
162
163 if (Size <= MinNodeSize)
164 {
165 if (polygons.Length > MaxQuadsPerLeaf)
166 throw new NotSupportedException(string.Format("Octtree: Quad density too big: current {0} max 4096 bbox {1}", polygons.Length, BoundingBox));
167
168 if (rooms.Length > MaxRoomsPerLeaf)
169 throw new NotSupportedException(string.Format("Octtree: Room density too big: current {0} max 255 bbox {1}", rooms.Length, BoundingBox));
170
171 return;
172 }
173
174 Split();
175 }
176
177 private void Split()
178 {
179 children = SplitCore();
180 polygons = null;
181 rooms = null;
182
183 BuildSimpleAdjaceny();
184
185 foreach (var child in children)
186 child.BuildRecursive();
187 }
188
189 private OctreeNode[] SplitCore()
190 {
191 var children = new OctreeNode[ChildCount];
192 var center = Center;
193 var childPolygons = new List<Polygon>(polygons.Length);
194 var childRooms = new List<Room>(rooms.Length);
195
196 foreach (var position in ChildPosition.All)
197 {
198 var childNodeBBox = new BoundingBox(center, center);
199
200 if (position.X == 0)
201 childNodeBBox.Min.X = bbox.Min.X;
202 else
203 childNodeBBox.Max.X = bbox.Max.X;
204
205 if (position.Y == 0)
206 childNodeBBox.Min.Y = bbox.Min.Y;
207 else
208 childNodeBBox.Max.Y = bbox.Max.Y;
209
210 if (position.Z == 0)
211 childNodeBBox.Min.Z = bbox.Min.Z;
212 else
213 childNodeBBox.Max.Z = bbox.Max.Z;
214
215 childPolygons.Clear();
216 childRooms.Clear();
217
218 var boxIntersector = new PolygonBoxIntersector(ref childNodeBBox);
219
220 foreach (var polygon in polygons)
221 {
222 if (boxIntersector.Intersects(polygon))
223 childPolygons.Add(polygon);
224 }
225
226 foreach (var room in rooms)
227 {
228 if (room.Intersect(childNodeBBox))
229 childRooms.Add(room);
230 }
231
232 children[position.Index] = new OctreeNode(childNodeBBox, childPolygons.ToArray(), childRooms.ToArray());
233 }
234
235 return children;
236 }
237
238 private void BuildSimpleAdjaceny()
239 {
240 foreach (ChildPosition position in ChildPosition.All)
241 {
242 var child = children[position.Index];
243
244 foreach (var face in Face.All)
245 child.Adjacency[face.Index] = GetChildAdjacency(position, face);
246 }
247 }
248
249 private OctreeNode GetChildAdjacency(ChildPosition position, Face face)
250 {
251 if (face.Direction == Direction.Positive)
252 {
253 if (position[face.Axis] == 0)
254 {
255 position[face.Axis] = 1;
256 return children[position.Index];
257 }
258 }
259 else
260 {
261 if (position[face.Axis] == 1)
262 {
263 position[face.Axis] = 0;
264 return children[position.Index];
265 }
266 }
267
268 return adjacency[face.Index];
269 }
270
271 public void RefineAdjacency()
272 {
273 Vector3 center = Center;
274 float size = Size;
275
276 foreach (var face in Face.All)
277 {
278 var node = adjacency[face.Index];
279
280 if (node != null && !node.IsLeaf && node.Size > Size)
281 {
282 Vector3 adjacentCenter = MovePoint(center, face, size);
283 adjacency[face.Index] = node.FindLargestOrEqual(adjacentCenter, size);
284 }
285 }
286 }
287
288 public QuadtreeNode BuildFaceQuadTree(Face face)
289 {
290 Vector3 faceCenter = MovePoint(Center, face, Size * 0.5f);
291 var quadTreeNode = new QuadtreeNode(faceCenter, Size, face);
292 quadTreeNode.Build(adjacency[face.Index]);
293 return quadTreeNode;
294 }
295
296 public void DfsTraversal(Action<OctreeNode> action)
297 {
298 action(this);
299
300 if (!IsLeaf)
301 {
302 foreach (var child in children)
303 child.DfsTraversal(action);
304 }
305 }
306
307 public static Vector3 MovePoint(Vector3 point, Face face, float delta)
308 {
309 if (face.Direction == Direction.Negative)
310 delta = -delta;
311
312 if (face.Axis == Axis.X)
313 point.X += delta;
314 else if (face.Axis == Axis.Y)
315 point.Y += delta;
316 else
317 point.Z += delta;
318
319 return point;
320 }
321
322 private struct TriangleBoxIntersector
323 {
324 private Vector3 center;
325 private Vector3 size;
326 private Vector3[] triangle;
327 private Vector3 edge;
328
329 public TriangleBoxIntersector(ref BoundingBox box)
330 {
331 center = (box.Min + box.Max) * 0.5f;
332 size = (box.Max - box.Min) * 0.5f;
333
334 triangle = new Vector3[3];
335 edge = Vector3.Zero;
336 }
337
338 public Vector3[] Triangle => triangle;
339
340 public bool Intersect()
341 {
342 for (int i = 0; i < triangle.Length; i++)
343 triangle[i] -= center;
344
345 edge = triangle[1] - triangle[0];
346
347 if (AxisTest(Y, Z, 0, 2) || AxisTest(Z, X, 0, 2) || AxisTest(X, Y, 2, 1))
348 return false;
349
350 edge = triangle[2] - triangle[1];
351
352 if (AxisTest(Y, Z, 0, 2) || AxisTest(Z, X, 0, 2) || AxisTest(X, Y, 0, 1))
353 return false;
354
355 edge = triangle[0] - triangle[2];
356
357 if (AxisTest(Y, Z, 0, 1) || AxisTest(Z, X, 0, 1) || AxisTest(X, Y, 2, 1))
358 return false;
359
360 return true;
361 }
362
363 private const int X = 0;
364 private const int Y = 1;
365 private const int Z = 2;
366
367 private bool AxisTest(int a1, int a2, int p0, int p1)
368 {
369 Vector3 v0 = triangle[p0];
370 Vector3 v1 = triangle[p1];
371 float e1 = edge[a1];
372 float e2 = edge[a2];
373
374 float c0 = e2 * v0[a1] - e1 * v0[a2];
375 float c1 = e2 * v1[a1] - e1 * v1[a2];
376 float rad = Math.Abs(e2) * size[a1] + Math.Abs(e1) * size[a2];
377
378 return (c0 < c1) ? (c0 > rad || c1 < -rad) : (c1 > rad || c0 < -rad);
379 }
380 }
381
382 private struct PolygonBoxIntersector
383 {
384 private BoundingBox bbox;
385 private TriangleBoxIntersector triangleBoxIntersector;
386
387 public PolygonBoxIntersector(ref BoundingBox bbox)
388 {
389 this.bbox = bbox;
390 this.triangleBoxIntersector = new TriangleBoxIntersector(ref bbox);
391 }
392
393 public bool Intersects(Polygon polygon)
394 {
395 if (!bbox.Intersects(polygon.BoundingBox))
396 return false;
397
398 if (!bbox.Intersects(polygon.Plane))
399 return false;
400
401 var intersector = new TriangleBoxIntersector(ref bbox);
402 var points = polygon.Mesh.Points;
403 var indices = polygon.PointIndices;
404
405 intersector.Triangle[0] = points[indices[0]];
406 intersector.Triangle[1] = points[indices[1]];
407 intersector.Triangle[2] = points[indices[2]];
408
409 if (intersector.Intersect())
410 return true;
411
412 if (indices.Length > 3)
413 {
414 intersector.Triangle[0] = points[indices[2]];
415 intersector.Triangle[1] = points[indices[3]];
416 intersector.Triangle[2] = points[indices[0]];
417
418 if (intersector.Intersect())
419 return true;
420 }
421
422 return false;
423 }
424 }
425
426 public OctreeNode FindLargestOrEqual(Vector3 point, float largestSize)
427 {
428 var node = this;
429
430 while (!node.IsLeaf && node.Size > largestSize)
431 {
432 Vector3 center = node.Center;
433
434 int nx = (point.X < center.X) ? 0 : 4;
435 int ny = (point.Y < center.Y) ? 0 : 2;
436 int nz = (point.Z < center.Z) ? 0 : 1;
437
438 var childNode = node.children[nx + ny + nz];
439
440 if (childNode.Size < largestSize)
441 break;
442
443 node = childNode;
444 }
445
446 return node;
447 }
448
449 public OctreeNode FindLeaf(Vector3 point)
450 {
451 if (!bbox.Contains(point))
452 return null;
453
454 if (children == null)
455 return this;
456
457 Vector3 center = Center;
458
459 int nx = (point.X < center.X) ? 0 : 4;
460 int ny = (point.Y < center.Y) ? 0 : 2;
461 int nz = (point.Z < center.Z) ? 0 : 1;
462
463 OctreeNode childNode = children[nx + ny + nz];
464
465 return childNode.FindLeaf(point);
466 }
467
468 public IEnumerable<OctreeNode> FindLeafs(BoundingBox box)
469 {
470 var stack = new Stack<OctreeNode>();
471 stack.Push(this);
472
473 while (stack.Count > 0)
474 {
475 var node = stack.Pop();
476
477 if (node.bbox.Intersects(box))
478 {
479 if (node.children != null)
480 {
481 foreach (OctreeNode child in node.children)
482 stack.Push(child);
483 }
484 else
485 {
486 yield return node;
487 }
488 }
489 }
490 }
491 }
492}
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