Getting normal of a plane

[danielv]

Hello everyone!

 

First post!

 

I have been playing around with bablyon (you can guess, I am not a pro graphics programmer) and the first issue I bumped into is: is there a simple way to get the normal of a surface?

 

If not, I was thinking on using the following to calculate the normal of a plane.

P---Q|   |R---T

Take (P-T) × (Q-R). Basically have the cross product of the plane's diagonals.

 

Is it at all a good solution? Is there a better or simpler way to do this?

 

Thanks

 

 

[GameMonetize]

Welcome

 

You are right. Just do the following:

var v1v2 = Q.subtract(P);var v2v3 = T.subtract(Q);var normal = BABYLON.Vector3.Cross(v1v2, v2v3);

[dsman]

So I have exact four corner points of plane mesh.  (Not just any point on plane mesh . But real corner points) . Assume P,Q,R,T

 

Resulting normal from both of follow code block A  and code block B   is different. Why is it so ? 

 

CODE BLOCK A : 

var v1v2 = P.subtract(T);var v2v3 = Q.subtract(R);var normal = BABYLON.Vector3.Cross(v1v2, v2v3);

CODE BLOCK B : 

var v1v2 = Q.subtract(P);var v2v3 = T.subtract(R);var normal = BABYLON.Vector3.Cross(v1v2, v2v3);

In case of BLOCK B I get normal = (0,0,0)

 

Am I being dumb here ?

[jerome]

Cross product of two collinear (parallel) vectors is null.

Check your vector (or points) order.