shader: use array indices when reading from gl_TessLevel*
gl_tessLevelOuter
and gl_TessLevelInner
don't support swizzles, but must be accessed as arrays.
Closes: #230 (closed)
gl_tessLevelOuter
and gl_TessLevelInner
don't support swizzles, but must be accessed as arrays.
Closes: #230 (closed)