Hello

c_trace fills the "normal" vector
I am a little rusty in math
Is it alwayes possible to define one and one only "normal" vector for any point of a surface ?
In case of a regular surface, for example a sphere or something similar such as a smooth hill, the answer is of course positive
It is the vector perpendicular to the plane tangent to the sphere in the point
What about irregular surfaces , for example some extremely irregular terrains ?

what do you mean with extremely irregular terrains? in math, every point of a surface has exactly one and only one normal (and the -normal which is normal * (-1)). the surface structure doesn't matter. but note that you can't derive some surface equations (mostly natural surfaces, artificial ones are easyer) so nearly all normals are just an approximation. this doesn't apply to computer games because there all surfaces are artificial...

joey.

edit: i'm speaking of normals with the length 1 here, just in case you were wondering...

what I know, normal it's just result of c_trace from entity central and using line, not box. So it's just angle of pixel. So doesn't matter how irregular terrain is.

Consider a cone, for example
You can not define a normal for the top vertex of the cone , because it is not possible to define a plane tangent to the surface of the cone in that point.
These points are called "singularities"
My question is
Given a surface, does alwayes one and one only normal exist(one only tangent plane) for each "non singular" vertex or some surfaces can have vertices with more than one normal ( more than one tangent plane) ?

in 3d graphics the normal of a vertex usually is the average of the normals of the faces the vertex is part of. this way you can also get the normal at the tip of a cone without problems.

Ah, yes, of course ,thanks