Inserting a 3D Point on 3DLine

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giskumar

Inserting a 3D Point on 3DLine

in General Discussion • Other • 10 months ago

Hi All,

I am having a 3D Line withcoordinates of P1 (x1,y1,z1), P2 (x2,y2,z2).

I also know an another point P on same line P (X,Y).

Please anybody let me know how can i calculate the Z value for point P.

Thanks,

Kumar

Replies(2)

asimes

Re: Inserting a 3D Point on 3DLine

10 months ago

Assuming you know how "far" it belongs on the line (midpoint, a quarter of the distance from P1 to P2, etc) you can use the parametric representation. The variable, t, is usually used to represent the parametric value for the point on the line you want. It's normal range is from 0.0 (P1) to 1.0 (P2) but it can go off the line segment with negative values or values greater than 1.0.

If you wanted to find the midpoint, you set t = 0.5 and do this:

float p3x = p1x+t*(p2x-p1x);
float p3y = p1y+t*(p2y-p1y);
float p3z = p1z+t*(p2z-p1z);

Edit: If you don't know how far you'd like it to be, you'll probably have to use the plane equation by plugging in your values of x, y, and the surface normal to calculate z.

Chrisir

Re: Inserting a 3D Point on 3DLine

10 months ago

yes, point can take 3 parameters, x,y and z.

Also look at lerp in the reference

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