how to use the knife tool ?

[Andy]

That surface is black because the first three vertices of the complicated polygon form an obtuse angle and that is causing a problematic surface normal calculation (surface-normals are used for lighting). It's best to break up the surface - triangulate will do this. You can also use Surface->change vertex order (one or more times) on polygons like that.



There's no edge selection in AC3D, since edges are essentially pairs of vertices. There are some functions which work on edges (selected vertices). The most useful is - after selecting two vertices, pressing 'l' to select a loop - which is just like a loop select in other software.



Loop select also works with surfaces - select some adjacent surfaces and press l to select a loop of surfaces - very handy.

[dvdl]

Hi Andy

will watch out next time - that was an issue in another software too where triangulating helped.

with edge selection that will do, just needed to know

thanks for the help