The tessellation control is the ability to see the wireframe of the geometry after displacement calculations. that feature does exist in mental ray, however, Softimage chose not to implement it as it required the use of contour shaders which Softimage also did not implement until XSI 7 or later.
Refresh optimization was implemented as "pixel tagging" which worked in early versions of Sumatra/XSI. It was very buggy and removed around XSI 2 or 3. In order for the feature to work, shaders had to implement specific routines to communicate with the renderer core. There were also problems for certain types of shaders, such as rayswitch or sprite where the shader would either modify or bypass the ray counters throwing off mental ray's internal state of what was happening. This lead to situations where pixels would either be falsely tagged or not tagged at all. In the end, it was more work to figure out which pixels to tag than to just render the images brute force. the idea to tag the pixels was more for cases where you'd render the entire scene in a single pass. With the introduction of passes, pixel tagging wasn't as high of a priority. Matt Date: Sat, 28 Jul 2018 00:30:15 +0200 From: “Sven Constable” <[email protected]> Subject: RE: Friday Flashback #345 To: "'Official Softimage Users Mailing List. Nice read. The features were amazing at the time (many of them are still by today). However, two features were not accomplished I think :) User Interface “Tesselation Control: Display of tesselated geometry used in rendering (e.g. for displacement mapping)” Maybe they referred to subdees. If so, it's kinda correct but didn't include displacement mapping by mental ray. Interactive Rendering “Refresh Optimization: Re-renders only the pixels affected by tuning” I don't think so. Mental ray introduced a feature called “incremental echo”, to speed up scene translation. Was demoed by someone from Softimage and I still have the video. But it was several years after Twister was announced. Also that feature wasn't per pixel based, to my knowledge. Other than that it still amazes me how ahead of it's time Softimage was. Sven ------ Softimage Mailing List. To unsubscribe, send a mail to [email protected] with "unsubscribe" in the subject, and reply to confirm.
