Introduction:

This tutorial describes a method of creating internal corners in rockwalled areas such as caves and trenches. Specifically, creating irregular floor-wall interfaces is discussed with respect to avoiding automatic brush deformation.

Create a rockwall as in tutorial 2. Copy and paste the wall and rotate it by 90° to create the floor and ceiling. Texture the visible surfaces with a suitable shader.

Move the vertices to create an uneven surface as in tutorial 2 but leave the corner vertices. The corner vertices need to be moved in pairs as described below.

In the images below, the selected vertex has been moved down by five grid units from it's original position. The circled vertex has been moved automatically in order to keep the brush convex.

The vertices of a quad remain coplanar when pairs of adjacent vertices are translated together thus keeping the brush convex without intervention.

Hence this is the method that is used to introduce irregularities into the corner brushes of the cavern.

It is possible to obscure the wall-floor-ceiling boundaries in this way as shown below.

Again, this brushwork can be kept as a prefab for future use. The in-game screenshots show the cavern with phong shading.