You could do a function on the XYZ coordinates of the ray as it travels through the volume, to 'irregularise' the rendering. If that makes sense. Never tried it. Of course, since you're doing this per-pixel/per-ray-step, you could find things slowing to a crawl rather quickly.
a|x On 1 Nov 2011, at 14:45, Chris Wood wrote: > Hi George > > I'm on training just now, but quick reply on that first point re rasterise or > trace/march: depends ;) > > With raymarching or tracing you can only handle shapes you create in the > shader at speed. Using a model of any sort gets *very* tricky. But if u can > define shapes as a distance function (or trace the surface) it can be quite > fast, and reflections shadows etc become easy. > > With mod() you just repeat a value, so if you use mod on the ray position the > ray loops through the same block of space. I.e any geometry inside that space > gets repeated. It's hard to do non-regular repeats though, and geometry > overlapping repeat areas gets glitchy. > > So, I guess raymarch if your geometry is complex but easy to generate as a > distance function. Anything else, rasterise it. > > Chris > > > > On 1 Nov 2011, at 13:34, George Toledo <gtole...@gmail.com> wrote: > >> Chris... >> >> >> After going through some investigations on using pixel shaders more, looking >> at stuff like the Raymarching/Raytracing for beginners thread at pouet, and >> IQ's website, I've wondered.... >> >> If I want to draw a bunch of little "squares" that have texture on them, >> does it make more sense to just be doing this in the pixel shader? I've >> heard some good arguments, and I'm starting to wonder about the CPU route >> (throwing a bunch of verts/triangles) at stuff (yeah, I know this isn't >> strictly CPU), vs. the pixel shader route. I don't have it worked out yet >> because I haven't quite got a handle on that mod=makes stuff repeat function >> (but I also haven't even sat down to). >> >> When I look at those amazing shadertoy shaders they're totally amazing (I'd >> suggest you look at them, or dl "my" zip of them off of kineme - nothing >> against cybero, but he hooked up a bunch of stuff that has nothing to do >> with the actual shaders). >> >> Also, what do you think about the idea of an app that simply pushes images >> through a CI filter chain and/or GL ES, writing the GL ES to a texture I >> guess? Then allowing one to write a- pictures, or b- movie clips? I think >> that the more I think about VUO, the more another part of me thinks about >> what I just described. >> _______________________________________________ >> Do not post admin requests to the list. They will be ignored. >> Quartzcomposer-dev mailing list (Quartzcomposer-dev@lists.apple.com) >> Help/Unsubscribe/Update your Subscription: >> http://lists.apple.com/mailman/options/quartzcomposer-dev/psonice%40gmail.com >> >> This email sent to pson...@gmail.com > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Quartzcomposer-dev mailing list (Quartzcomposer-dev@lists.apple.com) > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/quartzcomposer-dev/the_voder%40yahoo.co.uk > > This email sent to the_vo...@yahoo.co.uk _______________________________________________ Do not post admin requests to the list. They will be ignored. Quartzcomposer-dev mailing list (Quartzcomposer-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/quartzcomposer-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
