D3DXIntersectTri function (D3DX9Mesh.h)
Computes the intersection of a ray and a triangle.
Syntax
BOOL D3DXIntersectTri(
_In_ const D3DXVECTOR3 *p0,
_In_ const D3DXVECTOR3 *p1,
_In_ const D3DXVECTOR3 *p2,
_In_ const D3DXVECTOR3 *pRayPos,
_In_ const D3DXVECTOR3 *pRayDir,
_Out_ FLOAT *pU,
_Out_ FLOAT *pV,
_Out_ FLOAT *pDist
);
Parameters
-
p0 [in]
-
Type: const D3DXVECTOR3*
Pointer to a D3DXVECTOR3 structure, describing the first triangle vertex position.
-
p1 [in]
-
Type: const D3DXVECTOR3*
Pointer to a D3DXVECTOR3 structure, describing the second triangle vertex position.
-
p2 [in]
-
Type: const D3DXVECTOR3*
Pointer to a D3DXVECTOR3 structure, describing the third triangle vertex position.
-
pRayPos [in]
-
Type: const D3DXVECTOR3*
Pointer to a D3DXVECTOR3 structure, specifying the point where the ray begins.
-
pRayDir [in]
-
Type: const D3DXVECTOR3*
Pointer to a D3DXVECTOR3 structure, specifying the direction of the ray.
-
pU [out]
-
Type: FLOAT*
Barycentric hit coordinates, U.
-
pV [out]
-
Type: FLOAT*
Barycentric hit coordinates, V.
-
pDist [out]
-
Type: FLOAT*
Ray-intersection parameter distance.
Return value
Type: BOOL
Returns TRUE if the ray intersects the area of the triangle. Otherwise, returns FALSE.
Remarks
The D3DXIntersect 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, the value of [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 represents a change in coordinate systems. What holds true for Cartesian coordinates holds true for barycentric coordinates.
Barycentric coordinates define a point inside a triangle in terms of the triangle's vertices. For a more in-depth description of barycentric coordinates, see Mathworld's Barycentric Coordinates Description.
Requirements
| Requirement | Value |
|---|---|
| Header |
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| Library |
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See also