implement a shader-based pipeline

[brandonborkholder]

Initial work has already been done on a shader-based pipeline, see e9db0c1. We should extend this to cover the entire functionality of java.awt.Graphics2D.

[ghost]

In your humble opinion, which functionalities are particularly difficult to implement in the fixed pipeline but very easy to implement in the shader based pipeline? I hope you won't drop the former.

[brandonborkholder]

I haven't found anything that easier to implement in a shader than it is on
the CPU. However, I'd like to build a shader pipeline so that glg2d is
usable on mobile devices with OpenGL ES. I also think that some things can
be faster in a shader than on the GPU. For example,
StrokeShader.ghttps://github.com/brandonborkholder/glg2d/blob/master/src/main/java/glg2d/impl/shader/StrokeShader.gtakes
a path and draws it using the properties for a BasicStroke object.
This could be optimized even more using NVidia's Path api.

Graphics2D.setPaint(Paint) is one method that may be easier with a shader
(if you give it some non-constant color). But I haven't implemented this
yet and am not sure that's true.

However, rest assured I'm not dropping the fixed function pipeline (using
GL2 profile). I know that some people using glg2d are using it on old
hardware and don't have the latest video hardware.

[ghost]

You speak about mobile devices. Is it possible to build GLG2D without AWT?

[brandonborkholder]

Not without AWT. I'm assuming that you have the full JVM, but only OpenGL
ES2.