/PhysicsEngines/Bullet/Helpers.cs

 1using BulletXNA.BulletCollision;
 2using Delta.Rendering.Models;
 3using Delta.Utilities.Datatypes;
 4using BulletVector3 = Microsoft.Xna.Framework.Vector3;
 5using BulletMatrix = Microsoft.Xna.Framework.Matrix;
 6
 7namespace Delta.PhysicsEngines.Bullet
 8{
 9	/// <summary>
10	/// Helpers class used into the library.
11	/// </summary>
12	public static class Helpers
13	{
14		#region CreateFrom (Static)
15		/// <summary>
16		/// Helper method used for creation of Bullet TriangleMeshShape by 
17		/// populating data with vertices and indices gathered from out Mesh.
18		/// </summary>
19		/// <param name="mesh">The mesh to get data from.</param>
20		/// <param name="localSpaceMatrix">The local space matrix.</param>
21		/// <param name="invertTriangles">
22		/// if set to <c>true</c> we invert winding order of triangles.
23		/// </param>
24		/// <returns></returns>
25		public static TriangleMeshShape CreateFrom(Mesh mesh,
26			Matrix localSpaceMatrix, bool invertTriangles)
27		{
28			// extract the data from the physics mesh
29			TriangleMesh triangleMesh = new TriangleMesh(true, false);
30
31			// apply the local transform of the mesh so we get correct coordinates
32			Matrix TransMat = localSpaceMatrix;
33
34			ushort[] indices = mesh.Geometry.Data.Indices;
35
36			for (int i = 0; i < mesh.Geometry.Data.NumberOfUsedVertices; i += 3)
37			{
38				Vector vertex0 = Vector.Transform(
39					mesh.Geometry.Data.GetPosition(i), TransMat);
40
41				Vector vertex1 = Vector.Transform(
42					mesh.Geometry.Data.GetPosition(i + 1), TransMat);
43
44				Vector vertex2 = Vector.Transform(
45					mesh.Geometry.Data.GetPosition(i + 2), TransMat);
46
47				triangleMesh.AddTriangle(
48					BulletDatatypesMapping.Convert(vertex0),
49					BulletDatatypesMapping.Convert(vertex1),
50					BulletDatatypesMapping.Convert(vertex2));
51
52				// add Indices too
53				if (invertTriangles)
54				{
55					triangleMesh.AddIndex(indices[i + 2]);
56					triangleMesh.AddIndex(indices[i + 1]);
57					triangleMesh.AddIndex(indices[i]);
58				}
59				else
60				{
61					triangleMesh.AddIndex(indices[i]);
62					triangleMesh.AddIndex(indices[i + 1]);
63					triangleMesh.AddIndex(indices[i + 2]);
64				}
65			}
66
67			// Now create shape and return
68			return new TriangleMeshShape(triangleMesh);
69		}
70		#endregion
71
72		#region GetCenter (Static)
73		/// <summary>
74		/// 
75		/// </summary>
76		/// <param name="bbox"></param>
77		/// <returns></returns>
78		public static BulletVector3 GetCenter(BoundingBox bbox)
79		{
80			return new BulletVector3(
81				(bbox.Max.X + bbox.Min.X) * 0.5f,
82				(bbox.Max.Y + bbox.Min.Y) * 0.5f,
83				(bbox.Max.Z + bbox.Min.Z) * 0.5f);
84		}
85		#endregion
86	}
87}