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Re: Hey Josh would this help with the imposteor transitions?

#5
N810 wrote:Oh this articly from Nvidia looks somewhat usefull as well... although I don't see any code.
http://http.developer.nvidia.com/GPUGem ... _ch21.html
it definatey has to do with making good imposters of astroids though.
The is the paper to which I alluded and will probably end up trying. IMO it's the most promising technique :)
vfxguy wrote:How about volumetric billboards for imposters? Source :http://phildec.users.sourceforge.net/Re ... boards.php That looks quite intriguing and definetly might just work as LOD for asteroids or even all LOD objects.
Looked at it and not impressed, honestly seems like lazy brute force (and the results seem pretty underwhelming (not surprising considering, again, there's nothing clever going on here))
Vartul wrote:Will this help?-
https://www.youtube.com/watch?v=vJs9anEbHRc

This is a Unity plugin, but maybe Josh could discuss imposter problems with the creator?
This is the first technique I tried, a classic three-billboard imposter. Results are underwhelming, especially in space where the third plane is a lot more visible and annoying :P
“Whether you think you can, or you think you can't--you're right.” ~ Henry Ford
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Re: Hey Josh would this help with the imposteor transitions?

#6
Oh, that's what you mean by imposters... I thought you were still trying to billboard. I figured the thing to do would be just slap up a two-triangle plane with an image on it, and shade it so that it was lit correctly (e.g. facing towards the star it would be shaded to imitate being in shadow, facing away it would look bright, etc). I didn't figure that you'd see them up close... I'd just fade them out and fade the real stuff in when the player got close enough. I didn't think you were actually trying to make fully-functional fakes. :P Any help I've given has been useless, then. lol

I feel so stupid. :oops:
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Re: Hey Josh would this help with the imposteor transitions?

#7
Talvieno wrote:Oh, that's what you mean by imposters... I thought you were still trying to billboard. I figured the thing to do would be just slap up a two-triangle plane with an image on it, and shade it so that it was lit correctly (e.g. facing towards the star it would be shaded to imitate being in shadow, facing away it would look bright, etc). I didn't figure that you'd see them up close... I'd just fade them out and fade the real stuff in when the player got close enough. I didn't think you were actually trying to make fully-functional fake. :P Any help I've given has been useless, then. lol

I feel so stupid. :oops:
I mean you're right - that's the general idea. They won't be viewed from up close. But still, you need a way of representing the object roughly correctly from a distance, and a single, static image can't do that - because one image can only capture one angle of the object. So the real problem is that you need for this image to change according to the camera angle to the object. That change can of course be rough and inaccurate - but if you have a bunch of distant asteroids with the same model but rotated at different angle, you need for them not to all look like the exact same billboarded image :)
“Whether you think you can, or you think you can't--you're right.” ~ Henry Ford
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Re: Hey Josh would this help with the imposteor transitions?

#8
JoshParnell wrote:
Talvieno wrote:Oh, that's what you mean by imposters... I thought you were still trying to billboard. I figured the thing to do would be just slap up a two-triangle plane with an image on it, and shade it so that it was lit correctly (e.g. facing towards the star it would be shaded to imitate being in shadow, facing away it would look bright, etc). I didn't figure that you'd see them up close... I'd just fade them out and fade the real stuff in when the player got close enough. I didn't think you were actually trying to make fully-functional fakes. :P Any help I've given has been useless, then. lol

I feel so stupid. :oops:
I mean you're right - that's the general idea. They won't be viewed from up close. But still, you need a way of representing the object roughly correctly from a distance, and a single, static image can't do that - because one image can only capture one angle of the object. So the real problem is that you need for this image to change according to the camera angle to the object. That change can of course be rough and inaccurate - but if you have a bunch of distant asteroids with the same model but rotated at different angle, you need for them not to all look like the exact same billboarded image :)
Well, yeah, ideally that'd be what you'd do, but that requires quite a bit of math even at the simplest level. Most games - even Crysis and the CryEngine, for example - do billboarding by taking a single static image of the object and shading it. They'd it up between a number of pre-taken static images, too, and not do one image for all objects.

I've never actually heard of any games that do it the way you're trying to. :P I guess that's the source of my initial confusion. I'm sure you can manage it, though it might take you a while to figure it out if you haven't already. There isn't likely to be much documentation on this stuff lying around.

edit:
Yet again I spent a few hours on them today, and with great success! I revisited the classic three-billboard approach, but this time used a little magic to cull pieces of the billboards that aren't really appropriate to render (specifically, those that are almost at an oblique angle to the camera). The result is a whole lot cleaner than the previous result! It actually looks...really good! Combine that with adding in proper surface normal transformation so that the lighting is now globally correct, and you've got something that looks really darn convincing. Like, even at fairly close range! Ships and asteroids both look great using this technique. I haven't tried stations yet, but those will probably always be rendered with real geometry anyway.
Bravo, Mr. Parnell, bravo. :clap:
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Re: Hey Josh would this help with the imposteor transitions?

#9
Hi Josh did you check this site out : http://www.ericrisser.com/ ?

This guy seems to be the inventor of the technique which you want to use. He has other interesting artikles like this http://www.ericrisser.com/stuff/Renderi ... apping.pdf , which explains it in more detail. You could probably ask this guy if you have trouble with implementation. This one has a code sample at the end http://tr.eecs.ucf.edu/47/1/True_Impostors.pdf

Found another article on impostors as well : https://software.intel.com/en-us/articl ... -made-easy

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