Fragment Program and Pixel Locations

Guys, behave, I’ve had to detete the flames in this thread and that’s no fun.

@michaelgl, as knackered gently (and correctly) pointed out you should take a break between posts and maybe wait for a reply or try an edit or two. If readers see a whole series of posts from one poster it merges into a rambling monologue that nobody will read. Yes this is cool stuff, but take a breather between posts and read the posts of others in the thread to get a discussion going.

Hello all, sorry I haven’t checked in for a while, but I thought it was pretty much sewn up with the fact that there’s really no way for the fragment shader to affect pixel position. Why was trying this? Basically if I render to an FBO I have an image stored on the graphics card. If I then want to do some kind of image based rendering using that (or more) images I may need to arbitrarily rearrange them. So far the only thing that works is rendering a mesh of vertices the size of the screen (one vertex per pixel) and then using displacement mapping, as stated early in the thread. I was hoping there would be some faster/easier way.

This is not the only way, see fpo’s recent post where he itterates a parabola through a tangent space height map with negative bump displacement relative to his mesh.

Also the image based pass described in my post above could use dependent reads for the final fetches based on a shaded displacement vectors (or at least tangent space partial derivatives). As I said that could be an itterative search.

I don’t understand why folks are posting to every thread but the interesting one where fpo actually presents a working solution.

potmat, just a guess, but are you sure you can’t just render a single quad on the second pass and do the fragment displacements entirely in the frag shader somehow… at the least that would avoid the geometry overhead.

sorry dorbie, but i’m not much for self regulation. first of all if i tried to second guess myself i’m sure i would noever go anywhere. i have enough trouble getting through the day under the radar. as for the delete posts you didn’t delete anything i’ll miss. ii’m not going to let someone step on toes, but if you had deleted the negative posting before anyone caught wind of it no one would’ve had to reply to it.

michaelgl, I have better things to do with my time than nanny flamers all day long :-). The reason I deleted the flamefest was because I thought it directed unfair criticism at you, if I’d read it sooner I’d have deleted it sooner.

As for self regulation, it’s your reputation, not mine. You’re obviously a smart guy, that gets lost on some when you make a multi-post monologue, post without reading the contents of your own links, download something but post redundant questions before your download is done, or don’t check the contents of the thread you hastily post to.

Don’t let me cramp your style :slight_smile:

Happy posting.

P.M. me if you want to discuss this.


no problem, your points are taken, and i hope you didn’t get the impression that i was faulting you for any reason… i just ‘if’ as in literally ‘if’… not as in implying you are at any fault.

sorry i’m very literal… my brain isn’t adapted well i’m afraid for unexplicit meaning.

as for my posting irregularities and lazyness… a great deal of it is lazyness, i also like to think that the first words out of the horses mouth are the most honest, but mostly its just my 300mhz internet terminal and a weak internet connection. moving about the internet for me is clunky, and can get distracting as i move my attention to other machines.

unfortunately having development machines on the internet is a security risk. but i’m expecting a new (second hand) 1.5ghz internet terminal any day now as much as i hate to further demote my beloved portable. (i really need to put linux on it but the only solution on the market is a comercial app PartitionMagic).

and this is the last i have to say. i don’t want to muck up any thread, but would also prefer to air these grievances publicly. a little personal banter never hurt anyone even in a discressionary public forum.

basicly i have to do things my way or no way. i like it here… most comfortable bbs i’ve encountered so far. i’m confrontational and acccustomed to taking flak. i’m used to it so please forget it.

thanks for the ‘smart guy’ bit as well… i’m flattered really. i try my best to keep my priorities in order.

just for the record:

post redundant questions before your download is done, or don’t check the contents of the thread you hastily post to.
i’ve never posted any redundant questions (go ahead and try to fault me), and as for checking contents and hasty posting there are a lot of people in this forum who have been guilty of so much… especially when a thread gets grueling, its easy to make an oversight. and if you have a thought, get it out before you lose it is my motto.

i’ve never posted any redundant questions

“i’m downloading… just because you didn’t say so explicitly, do these demos demonstrate proper silhouettes?”

You need a new motto :slight_smile:

FWIW, I’m not coming down on you just offering some friendly advice, and you’re right this is off topic but my intent is to nip this in the bud.

P.S. I do see the contributions you make that’s why the personal attack I deleted here was so unfair. More people could benefit from your contributions if you kept your powder dry, that’s why both knackered and I went to your defense and offered the advice we did. Thanks for listening, neither of us are perfect, heck if knackered and I are offering you advice on netiquette then maybe there’s something behind it :slight_smile:

“i’m downloading… just because you didn’t say so explicitly, do these demos demonstrate proper silhouettes?”

honestly i thought it would be useful for anyone reading the threads to know what was in the demos without having to download them… they are decent downloads and since i don’t have the hardware to just up and run them the only way i could verify this without asking would be to get around to picking the shaders apart myself or maybe pick apart the discussion for hints (whatever might be easier, a straight statement would’ve been easier for everyone)… plus at the same time i was kind of making it known that some people would like to see demos with silhouettes even if they aren’t perfect. as soon as i get my hands on some hardware that can run this stuff you can bet i will give some thought to perfecting the silhouettes if someone doesn’t beat me to it… i’m also curious if the silhouettes are just ‘not good enough’ for extreme displacement, or if they work well enough for suddle displacement… personally the screens all look really good to me whenever the surfaces are not obsessively displaced.

FWIW, I’m not coming down on you just offering some friendly advice, and you’re right this is off topic but my intent is to nip this in the bud.
believe i try to keep everyone happy. but its easier for you to sit back and complain, but for me its difficult to empathize with you because i can’t really grasp what your issues are or even how i would begin to reform my behavior without driving myself crazy.

all i expect of people is personal empathy. you can’t force people to behave a certain way without asking really too much of them psychologicly. i wouldn’t inflict anything on anyone here that i wouldn’t inflict on myself… and i don’t expect more than that of anyone.

i will try to keep people happy… but my reality/culture doesn’t really resemble silicon valley office etiquete or an american sitcom (both of which i find equally confounding) so its personally difficult for me to relate. but i try never the less.
i’m not going to let people’s requests of me warp my brain though. so if i’m really too much to handle, i can just walk away, or resort only to antiseptic language, which will undoubtedly limit my interaction with this community purely to a one of absolute necessity as opposed to comfort and outgoing support.

i’m all for healthy bbs communities… unfortunately in my experience most bbs communities do not really meet this criterion. this bbs so far is quite bareable and informative. i’m really shocked how much i’ve frequented this forum since i registered and in relative comfort.

for now though this is enough words on such matters for me. lets move forward please. not that these sorts of diversions are not a necesarry part of a healthy introspective bbs community.

i would be very happy to discuss silhouette conformant relief mapping in here as well as other inverse fragment sampling techniques in this thread as far as potmat and others would allow it.

i really believe a derivative of this technique will be a major cornerstone of low-level ‘image synthesis’ in the years to come and i would be happy to discuss it in any sort of divergeant fashion.

i’m mostly intrested in harnessing the technique for sub vertex smoothing and not just merely detail displacement mapping. preferably i would like to see a sub vertex smoothing technique that is indapendant of the linearity of the base geometry… ie. the displacement map should not reflect the linear nature of the aproximated geometry it is applied to.

you can easilly generate a displacement map by projecting a high resolution model onto a low resolution model, but how could you use a displacement map designed to be applied to a ‘perfect’ aproximation of the geometry, even when the geometry is less than perfect.

also interested in better techniques for producing per vertex curvature aproximations, especially generating consistant curvature data given a control mesh and a parametric sampling technique. ie. nurbs

PS: still interested in what is a fragment ‘KIL’ operation and where can i read about it (i have looked)… not in my dated Cg docs best i can tell, and i can’t figure out what to give a browser to work with. should i just download new docs?

EDIT: found DISCARD operator in a Cg frag program.

Sigh, I could kick myself for encouraging this.

Please keep your ill-founded stereotypes to yourself and no more threadjacking.