3d normal calculations

[zawran]

Is the following a correct way of calculating the normal of a triangle surface?

Code: [Select]

1
|\
| \
|  \
|___\
2    3

Local ax:Float = x2-x1
Local ay:Float = y2-y1
Local az:Float = z2-z1
Local bx:Float = x3-x1
Local by:Float = y3-y1
Local bz:Float = z3-z1
Local nx:Float = (ay*bz) - (az*by)
Local ny:Float = (az*bx) - (ax*bz)
Local nz:Float = (ax*by) - (ay*bx)
Local length:Float = Sqr(nx*nx + ny*ny + nz*nz)
nx :/ length
ny :/ length
nz :/ length

x1-x3, y1-y2, z1-z3 are the position vectors of the three points of the triangle. Nx,ny,nz are the final normals (hopefully).

[hellfire]

Looks fine.
See cross-product:

Some sort of oop-structure for 3d vectors usually helps to get such things running straight.

[zawran]

I had made a question to why a light was shining wrong, but it turned out, that it was me not understanding that a directional light, its not a position but a vector of the direction of the light that it gets. So I got the light to behave as I wanted. One less thing to worry about

[Shockwave]

It's nice when things resolve themselves like that