The transparency of stencil shadows can be set through mtl_shadow.alpha (default = 50), and their color can be set through mtl_shadow.diffuse_blue, mtl_shadow.diffuse_green, and mtl_shadow.diffuse_red (default = 0,0,0 = black).

mat_shadow.alpha = 10; // brighter
mat_shadow.alpha = 90; // darker
Default is 50.

Z-pass stencil shadows are faster than z-fail shadows, but don't allow to move the camera into a shadow volume. They are the best method for elevated 3rd person cameras, like in an isometric game. In first person mode the player's shadow is automatically switched off when z-pass stencil shadows are activated.
Z-fail stencil shadows are a little slower than z-pass shadows, but more robust. They are independent of the camera position and allow LOD models to differ greatly from the original model, which would otherwise cause shadow faults with the z-pass algorithm. Z-fail shadow volumes are columns rather than cones, although the difference is only visible with close lights, and can lead to disconnected shadows of connected meshes in such a case . A script can be used for tracing a ray from a light source to the camera, and automatically switching to z-fail shadows when the ray hits an obstacle.