- use 'const float *' and array size in some function declarations. - replace macros for BLI_math functions INPF, VECCOPY, VECADD etc. - remove unused VertRen.clip struct member. - remove static squared_dist() from 2 files, replace with BLI_math function len_squared_v3v3(). - use vertex arrays for drawing clipping background in the 3D viewport.