How to paint a portion of a mesh with a brush?

Blitz3D Forums/Blitz3D Programming/How to paint a portion of a mesh with a brush?

Ah I found it! Never seen the demo..

But meanwhile I realised I'm aiming for a wrong course.
It's better to add a sprite beneath the players feet.
But...the mesh ain't flat. Basicly I need to know the steepness of a certain section.
I can Linepick for the Y coordinate: left top, left right, bottom left, bottom right.

But then I need to use the four coordinates to calculate the rotation of the sprite.

Eg: I am standing on a hill, and I want to place a sprite aligned to the steepness of the hill.