Preliminary tests on the actor made clear the necessity for anti-aliasing within the program.
Patches within Isadora vary in density based on the amount and size of media within it. A patch that shows still images with be slightly faster than those that have video files. The same is true for patches with a combination of both along with various effects. Having a high level of anti-aliasing can slow the computers processing and cause lag. It is imperative that in live performances cues trigger at the precise moment they are meant to. Too much lag in a heavy media show could lead to eventual crashing of Isadora or the computer itself. To help compensate for the diverse types of performances and machines, 8 different levels of anti-aliasing were incorporated into the actor depending on the needs of the event. The levels range on a scale from 0-7. Zero meaning no anti-aliasing is being applied to the map. From there the number of tests that are performed in the code increases exponentially. The number of tests are based on jitter point arrays for 2,3,4,8,15,24 and 66 jitters.
Anti-aliasing is only performed when the map is initially drawn and when there are any subsequent changes to it. When mapping a still image this effect can not be observed. However, if anti-aliasing were constantly being applied, mapping a video file with changing frames would dramatically slow down the playback because the map would have to redraw every frame. Even though the anti-aliasing is applied only when the map is drawn or redrawn, it is recommended that when mapping in Isadora the anti-aliasing be set to zero to avoid any issues. Changing anti-aliasing value temporarily slows the media down to allow for recalculation of the alpha mask. At the very least, mapping at 7 optimization is discouraged since the number of tests being performed on the pixels is substantially higher than the other levels.
Here is a picture comparing the different angles of an image with no anti-aliasing and fully optimized level 7 anti-aliasing with 66 jitter points.
Here is a time-lapse video showing the 8 different states of anti-aliasing used in the Isadora Actor.
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