D3DXIntersectTri

Returns the intersection of the specified ray with the specified triangle, if they intersect.

BOOL D3DXIntersectTri(
  CONST D3DXVECTOR3* p0,
  CONST D3DXVECTOR3* p1,
  CONST D3DXVECTOR3* p2,
  CONST D3DXVECTOR3* pRayPos,
  CONST D3DXVECTOR3* pRayDir,
  FLOAT*             pU,
  FLOAT*             pV,
  FLOAT*             pDist
);

Parameters

p0

[in] Pointer to a D3DXVECTOR3 structure, describing first triangle vertex position.

p1

[in] Pointer to a D3DXVECTOR3 structure, describing second triangle vertex position.

p2

[in] Pointer to a D3DXVECTOR3 structure, describing third triangle vertex position.

pRayPos

[in] Pointer to a D3DXVECTOR3 structure, specifying the position of the ray.

pRayDir

[in] Pointer to a D3DXVECTOR3 structure, specifying the direction of the ray.

pU

[out] Pointer to a barycentric hit coordinate, U.

pV

[out] Pointer to a barycentric hit coordinate, V.

pDist

[out] Ray-intersection parameter distance.

Return Values

Returns TRUE if the ray intersects the area of the triangle. Otherwise, returns FALSE.

Remarks

The D3DXIntersectTri function provides a way to understand points in and around a triangle, independent of where the triangle is actually located. This function returns the resulting point by using the following equation: V1 + U(V2-V1) + V(V3-V1).

Any point in the plane V1V2V3 can be represented by the barycentric coordinate (U,V). The parameter U controls how much V2 gets weighted into the result and the parameter V controls how much V3 gets weighted into the result. Lastly, 1-U-V controls how much V1 gets weighted into the result.

Barycentric coordinates are a form of general coordinates. In this context, using barycentric coordinates simply represents a change in coordinate systems. What holds true for Cartesian coordinates holds true for barycentric coordinates.

Requirements

  Header: Declared in D3dx8mesh.h.
  Import Library: Use D3dx8.lib.