Blender Git Loki

[T40792] Optimisations for FCurve Drawing - Lower sampling precision when "High Quality" drawing disabled

When the "High Quality Line Drawing" option (View menu) is disabled,
the sampling rate (i.e. the size of timesteps to use when sampling
the FCurve for drawing it in most cases now) is set to be quite low
(i.e. at 0.1 frame increments). This amounts to at most 10 sub-steps.

In one test file (with a wide window), this had the effect of improving
the performance by over 3x. It's still not as good as a sampling-free
approach, but for this functionality is still needed for FModifiers,
so it's better that we can optimise this.