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 <[email protected]> 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 ([email protected]) > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/quartzcomposer-dev/psonice%40gmail.com > > This email sent to [email protected] _______________________________________________ Do not post admin requests to the list. They will be ignored. Quartzcomposer-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/quartzcomposer-dev/archive%40mail-archive.com This email sent to [email protected]
