🚀 go-pugleaf

Hi,

I have a problem with a program I am trying to write:

Does anyone know how to find the intersection of a line and plane
in simple x,y and z cartesian coordinates.  I have a model made
up of facets, each facet being defined by 4 points.  The working
envelope that this model is in, is then scanned from the bottom
to the top.  However I can't work out how to calculate the z
coordinate along the scan line that may intersect with a facet.

The scanning line is always horizontal and is defined with the
x and y coordinates remaining the same, with one end of the line
minus z and the other end positive z. As an example at what point
does the line whose start point is (54,46,-100) and whose end
point is (54,46,100) intersect with a plane facet defined by 4
points in a anti-clockwise direction point 1 (40,20,-70),
point 2 (40,60,-40), point 3 (120,60,-40) and point 4 (120,20,-70).

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