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Mesh | |
Inheritance HierarchyAb3d.DirectX.UtilitiesMeshCollider
Namespace: Ab3d.DirectX.Utilities
Assembly: Ab3d.DXEngine.Wpf (in Ab3d.DXEngine.Wpf.dll) Version: 7.0.8865.1045
Syntaxpublic class MeshCollider
The MeshCollider type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | MeshCollider(MeshBase) | Constructor with DXEngine's mesh (mesh must implement IRayHitTestedObject interface). |
| MeshCollider(MeshGeometry3D) | Constructor with WPF's MeshGeometry3D. DXEngine's DXMeshGeometry3D will be generated from WPF mesh. |
Properties| Name | Description | |
|---|---|---|
 | LastIntersectionPositionIndex | Gets the position index of a position that was the first to be inside the mesh (this is not the closest position). This is set only when calling HasIntersection with mesh as parameter. Default value -1 indicates no position is inside the mesh. |
| Mesh | Gets the mesh that was used to create this MeshCollider |
Methods| Name | Description | |
|---|---|---|
| GetClosestPosition | GetClosestPosition returns a DXRayHitTestResult with HitPosition set to the closest position on the mesh, DistanceToRayOrigin is set to the distance from the specified position to the position on the mesh and TriangleIndex is set to the position index in the Positions array (or vertex buffer array). |
| HasIntersection(MeshBase) | Returns true when the specified mesh intersects with the mesh that was used to create this MeshCollider. |
| HasIntersection(BoundingBox, Boolean) | Returns true when the specified BoundingBox intersects with the mesh. When checkEachCorner is false, then only a simple bounding box intersection check is done. This is the fastest but the least accurate. When checkEachCorner is true (by default), then the center position and all 8 corners of the BoundingBox are checked for intersection. |
| HasIntersection(MeshBase, Matrix) | Returns true when the specified mesh intersects with the mesh that was used to create this MeshCollider. |
| HasIntersection(MeshGeometry3D, Transform3D) | Returns true when the specified MeshGeometry3D intersects with the mesh that was used to create this MeshCollider. |
| HasIntersection(Rect3D, Boolean) | Returns true when the specified Rect3D intersects with the mesh. When checkEachCorner is false, then only a simple bounding box intersection check is done. This is the fastest but the least accurate. When checkEachCorner is true (by default), then the center position and all 8 corners of the Rect3D are checked for intersection. |
| IsInsideMesh(Point3D) | Returns true when the specified position is inside the mesh. |
| IsInsideMesh(Vector3) | Returns true when the specified position is inside the mesh. |
Fields| Name | Description | |
|---|---|---|
 | PrimaryRayDirection | Direction of the ray that is first used for hit testing. Default value is (0, 1, 0). |
| SecondaryRayDirection | Direction of the ray that is used to confirm the hit test results of the first ray. This prevents invalid results in case the ray just touches the mesh. Default value is (0, 0, 1). |
RemarksMeshCollider can be used to test collision between mesh and a 3D position, Rect3D, BoundingBox or another mesh.
MeshCollider uses ray hit testing to determine if a position is inside a mesh. This is done by creating a ray from the specified position and into the direction specified by PrimaryRayDirection (this direction can be any direction). Then a ray hit testing is performed and number of hits is counted.
If number of hits is even (1, 3, 5, etc.) then the position is inside the mesh. If number of hits is odd (0, 2, 4, etc.) then the position is outside the mesh.
When number of hits is even, then the accuracy of the result is confirmed by doing another check with ray in SecondaryRayDirection. This prevents false positive results when the ray just touches the mesh in one position.
When checking if another mesh is intersecting the mesh that was used to create this MeshCollider, then each position in the mesh is checked for intersection. To speed up this process first ten positions that are equally distributed in the mesh are checked. If no intersection is found, then all other positions are checked (duplicate positions are checked only once). The first intersected position stops the check. The index of this position is written to LastIntersectionPositionIndex property.
To make hit testing significantly faster, an OctTree is generated from the mesh that was used to create this MeshCollider.
MeshCollider does not support transforming the mesh that was used to create this MeshCollider. To achieve that you need to transform the mesh by yourself. For WPFs' MeshGeometry3D this can be done by using the Ab3d.Utilities.MeshUtils.TransformMeshGeometry3D method. The DXEngine's mesh can be transformed by transforming each position by Vector3.Transform method and normals by Vector3.TransformNormal method.
See Also