Walls are crucial in most of our problem setups and hence we have a variety of walls to suit the needs of our users.

Infinite Wall

Infinite wall

A standard wall is a plane defined as {x: normal*x=position}, with normal being the outward unit normal vector of the wall. A particle touches a standard wall if position-normal*x<=radius. Given the normal, a wall can be placed at any given position.
The black strip denotes the inner side of the wall. The particles interact with the wall along the blue strip.

Finite Wall

A block of wall formed by set of infinite walls.

Finite wall is basically a set of infinite walls or A finite wall is convex polygon defined by a set of normals normal_i and positions position_i. For example, to create a polygonal obstacle (in 2D or 3D), we consider the a set of infinite walls and create the obstacle as an intersection of all the infinite walls. See above figure corresponding to finite walls.