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I'm struggling with this idea of creating two particles in 3d and draw a tube between them. I can't figure out how to properly set the angle of the tube. I've used two approaches:

  1. calculating the angle with the square root dot product divided by the length of the vectors.
  2. cartesian to polar function which calculates the y and z rotation values

I'm obviously missing something (and I'm not that good in math). So what's my approach?

Thanks in advance! See below what I have so far. enter image description here

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    $\begingroup$ Ill give you a hint, use cross product. $\endgroup$ – joojaa Jun 25 '16 at 7:01
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The simplest solution is to use a lookat matrix. This is a matrix calculated from a "eye" point, a "target" point and an up vector.

The resulting matrix will then make the Z axis point from the eye to the target and the y axis in the general direction of up.

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  • $\begingroup$ Could you expand on how this can be used to determine the angle of the tube? Sorry if I'm missing something obvious... $\endgroup$ – trichoplax Jun 26 '16 at 0:09
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    $\begingroup$ @trichoplax you don't even need the angle. You rarely, if ever, do for setting up geometry. You can nearly always skip getting the angle explicitly because 99% of the time you will be feeding it into a sin or cos right after you get it from a asin or acos. $\endgroup$ – ratchet freak Jun 26 '16 at 0:20

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