From guest Tue Feb 22 09:33:04 1994 From: Bernd Froehlich Message-Id: <9402221633.AA09760@viswiz.gmd.de> Subject: Transparency To: info-performer@sgi.sgi.com Date: Tue, 22 Feb 94 18:18:09 MET Status: OR Hello, how is transparency realized in Performer? In GL one has to render the opaque polygons first, then the transparent ones in decreasing order of distance from the eyepoint. Sorting is usually too expensive, so just drawing the opaque polygons first and the transparent ones last is ok for most cases. Is this supported in Performer and how? Thanks --Bernd bernd@viswiz.gmd.de From guest Tue Feb 22 10:36:31 1994 Message-Id: <9402221835.AA17909@surreal.asd.sgi.com> To: Bernd Froehlich Cc: info-performer@sgi.sgi.com Subject: Re: Transparency In-Reply-To: Your message of "Tue, 22 Feb 94 18:18:09 +0700." <9402221633.AA09760@viswiz.gmd.de> Date: Tue, 22 Feb 94 10:35:04 -0800 From: Jim Helman Status: O By default, Performer draws all transparent geosets and billboards (which are usually transparent) last. The rendering order is less important when using multisample transparency (msalpha == screendoor) than when using blendfunction. But with blended alpha, you pick up the color of the last thing drawn behind the partially transparent object, which is often not the correct backdrop. Fortunately, msalpha is our default on Reality Engine. The downside is fewer alpha levels. Note that node draw callbacks disable the draw-last feature since the geometry in the subgraph rooted at that node must be drawn within the scope of its pre/post draw callbacks. If anyone has a need for better sorting, e.g. someone needs lots of blended alpha billboards, they should contact us. We have ways. rgds, -jim helman jimh@surreal.asd.sgi.com 415/390-1151 From: Bernd Froehlich Subject: Transparency To: info-performer@sgi.sgi.com Date: Tue, 22 Feb 94 18:18:09 MET Hello, how is transparency realized in Performer? In GL one has to render the opaque polygons first, then the transparent ones in decreasing order of distance from the eyepoint. Sorting is usually too expensive, so just drawing the opaque polygons first and the transparent ones last is ok for most cases. Is this supported in Performer and how? Thanks --Bernd bernd@viswiz.gmd.de From guest Mon Apr 11 11:13:01 1994 Date: Mon, 11 Apr 94 13:05:32 CDT From: reedwhit@skips.dseg.ti.com (Reed Whittington) Message-Id: <9404111805.AA28700@skips.dseg.ti.com> To: iris-performer@sgi.sgi.com Subject: Alpha/Trans Defaults Status: OR I'm making enhancements on some gl code and trying to get alpha texture rendering tuned on an RE2 to work as well as Performer's defaults. I would like to know Performers defaults for mssize, msalpha, blendfunction/afunction ... to enable the "best looking" alpha/transparency rendering for a Onyx (5.2 IRIX) RE2 w/ 4RMs. Thanks, Reed --------------------------------------------------------------------- Reed Whittington reedwhit@dseg.ti.com Texas Instruments Visual Simulation Technology Development ---------------------------------------------------------------------