Commits on Sep 10, 2014

1. Simplify rectangular texture program …

   Share most of the code between rectangular and texture programs by
   using a texture space transformation which modifies texture coordinates
   per-vertex. This also allows the elimination of the flipped texture
   coordinates, further simplifying things. This is a preliminary step
   to make it easier to implement masking to layer boundaries.

   

   mrobinson committed Sep 10, 2014
   612c604

2. Abstract shader compiler into ShaderProgram struct …

   This simplifies things slightly and better encapsulates the shared
   logic of shaders.

   

   mrobinson committed Sep 10, 2014
   9f375c0

3. Set the SolidLineProgram texture space transform …

   Things seem to function properly without this, but this is more correct.

   

   mrobinson committed Sep 10, 2014
   7543bb1

4. Eliminate z-coordinate in vertex position attributes …

   The z-coordinate is always 0, so we can just make it a constant in the
   shader. This should result in less data streaming to the GPU when the
   vertex coordinates change with clipping support.

   

   mrobinson committed Sep 10, 2014
   19ff34e

5. Do not pass texture coordinates to shader …

   This can always be inferred from the unit rectangle coordinates, so we
   simply omit them from the list of attributes passed to the shader.

   

   mrobinson committed Sep 10, 2014
   d14f4de