clean up default shader

[chiefcll]

Remove Extra params - and double texture2d call which wasn't used. The vertex logic matches the batched shader logic.

[jfboeve]

Code looks like it should work. However the test is stuck on after a linear gradient test.

[chiefcll]

This was needed
v_nodeCoords = a_nodeCoords;

Other shaders use the default vertex shader... good to know 😅