public Interface GroupStrategy

This class provides hooks which are invoked by DecalBatch to evaluate the group a sprite falls into, as well as to adjust settings before and after rendering a group.

A group is identified by an integer. The beforeGroup() method provides the strategy with a list of all the decals, which are contained in the group itself, and will be rendered before the associated call to afterGroup(int).
A call to beforeGroup() is always followed by a call to afterGroup().
Groups are always invoked based on their ascending int values. Group -10 will be rendered before group -5, group -5 before group 0, group 0 before group 6 and so on.
The call order for a single flush is always beforeGroups(), beforeGroup1(), afterGroup1(), ... beforeGroupN(), afterGroupN(), afterGroups().

The contents of the beforeGroup() call can be modified at will to realize view frustum culling, material & depth sorting, ... all based on the requirements of the current group. The batch itself does not change OpenGL settings except for whichever changes are entailed DecalMaterial#set(). If the group requires a special shader, blending, getGroupShader(int) should return it so that DecalBatch can apply it while rendering the group.