minor changes on Font class.
refactoring
refactoring
refactoring
Revert "refactoring"

This reverts commit a57737823ab48ac90d481b44c1ea5cd242d77647.
refactoring
nicer interface for GLSL pre-processors. Shader class allows now to specify custom pre-processor pipeline.
nicer interface for GLSL pre-processors. Shader class allows now to specify custom pre-processor pipeline.
using state stacks for texture parameters.
using state stacks for texture parameters.
using state stacks for texture parameters.
using state stacks for texture parameters.
using state stacks for texture parameters.