Question

I’m trying to build a thing that renders point cloud data stored in a specific way to a canvas using Javascript.

The data is stored as (JSON, where -> represents a range of values including the two extremes)

{“xangle”:-Math.PI*2 -> Math.PI*2,”yangle”: -Math.PI*2 -> Math.PI*2,”disntancefromorigin”:10,”colour”:blue}

I’ve been having some trouble working out what the maths should be for turning the xangle, which represents the angle away from the x axis the line is and the yangle, which is the same but from the yaxis, and the distance from the origin into a “3d” point.

I’ve been running code which generates a large array of points the same distance from the origin with the same distance and trying to manually brute force the algorithm till i got it right – but that didn’t help much.

thanks for any help, if I’ve not made something clear or you want to see the code just ask.

EDIT: I should add, I’m just going for an Orthographic representation (at least till I can get that working)

Answer 1

r = distancefromorigin
y=r*cos(yAngle)
x=r*cos(xAngle)
z=+-r*sqrt( 1-cos^2(yAngle) - cos^2(xAngle) )

Edit: Last equation is from x^2 + y^2 + z^2 = r^2

You cannot say if you have to pick + or – because your problem is ill defined!