02-04-2016, 06:20 PM
By default orientation is calculated automatically using an enhanced Parallel Transport Frame (PTF) algorithm. That's why it changes slightly when you add/remove CP's. To prevent that flag some CP's (at least one before your visible "track", one behind) as OrientationAnchors. PTF then takes this anchors as start/end conditions, thus calculating only a smooth path between those anchors. Just play with anchors in the editor to see it at work and get the idea.
Note that when you enable an anchor, the current orientation (usually auto-calculated) is set, but you can rotate the transform to alter that.
Also note that this has a nice performance side effect, because when you change the spline, only orientation of the affected anchor group (segments between two anchors) needs to be recalculated. Say we have a spline with 1000 CP's. When you change the first CP, whole orientation needs to be recalculated. If you set CP 500 to be an anchor group, only the first 500 CP need an orientation update. But that's just spline refreshment magic happening behind the scenes...
Note that when you enable an anchor, the current orientation (usually auto-calculated) is set, but you can rotate the transform to alter that.
Also note that this has a nice performance side effect, because when you change the spline, only orientation of the affected anchor group (segments between two anchors) needs to be recalculated. Say we have a spline with 1000 CP's. When you change the first CP, whole orientation needs to be recalculated. If you set CP 500 to be an anchor group, only the first 500 CP need an orientation update. But that's just spline refreshment magic happening behind the scenes...
