# How do I get the point in the triangle intersected with a ray

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akira32    112
How do I get the point in the triangle intersected with a ray? The dist is the distance between the intersected point in trainagle and the origin of the ray? D3DXIntersectTri(&v_tri[0],&v_tri[1],&v_tri[2],&originW,&dirW,&U,&V,&dist);

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Evil Steve    2017
Quote:
 Original post by akira32How do I get the point in the triangle intersected with a ray?
U and V are the Barycentric coordinates of the intersection point.

Quote:
 Original post by akira32The dist is the distance between the intersected point in trainagle and the origin of the ray?
Yes.

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akira32    112
D3DXIntersectTri(&v1,&v2,&v3,&originW,&dirW,&U,&V,&dist);D3DXVECTOR3 vec1=originW+dist*dirW;float W=1-(U+V);D3DXVECTOR3 vec2;//intersected point in trianglevec2.x=(v1.x*W)+(v2.x*U)+(v3.x*V);vec2.y=(v1.y*W)+(v2.y*U)+(v3.y*V);vec2.z=(v1.z*W)+(v2.z*U)+(v3.z*V);

Is the vec1 equal to vec2?

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Buckeye    10747
Yep.

FYI, you don't need to do the coordinates separately. D3DXVECTOR3 overloaded operators allow:

vec2 = v1*W + v2*U + v3*V;

Be aware: dist may be negative, which means dirW is pointing away from the triangle.

Also, be aware of the return value of D3DXIntersectTri. If false, that represents the condition where dirW is parallel to the plane of the triangle.

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