Poll of the Day > Hey programming people; is it possible to render a hologram onto a texture?

(+) Yeah! (+)

https://en.wikipedia.org/wiki/Holography#/media/File:Holographic_autoportrait,_Sofia.jpg

It's an effect I've NEVER seen in a video game
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Possible, yes, but it would take somewhere in the realm of 500K displays to actually work.

Questionmarktarius posted...

Possible, yes, but it would take somewhere in the realm of 500K displays to actually work.

wouldn't it just required a pair of parallax lightmaps and a sinusoidal displacement map? Or is there more to it than that?

EDIT: And I do mean by using the same technique as real holograms... not just using a 3d cubemap with a 3d model in it
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Lokarin posted...

Questionmarktarius posted...

Possible, yes, but it would take somewhere in the realm of 500K displays to actually work.

wouldn't it just required a pair of parallax lightmaps and a sinusoidal displacement map? Or is there more to it than that?

EDIT: And I do mean by using the same technique as real holograms... not just using a 3d cubemap with a 3d model in it

You'd have to replicate the light field imaging that makes holograms work, which would take a pretty ridiculous display resolution.
https://upload.wikimedia.org/wikipedia/commons/a/a5/Holographic_recording.jpg

Lokarin posted...

https://en.wikipedia.org/wiki/Holography#/media/File:Holographic_autoportrait,_Sofia.jpg

It's an effect I've NEVER seen in a video game

A video game mirror.

what exactly is the effect? reading about it it just sounds like it's a 3D image recorded onto a 2D surface (ie: in such a way that it changes depending on perspective). so yeah, a mirror in a game, or even just 3D graphics as a whole, which generate 2D representations of 3D models. it's more like that 3D graphics are already doing what holograms are doing so much better that you don't even notice.

Lokarin posted...

EDIT: And I do mean by using the same technique as real holograms... not just using a 3d cubemap with a 3d model in it

that's like saying "using the same technique as real photographs, not just using a 2d image". are you looking for a full light-ray simulation or something? you could maybe do holographic ray-tracing, where you generate ray-tracing results from multiple perspectives. the result would have to be a gif or like one of those 360 degree videos or something.

thinking about it, maybe you mean that the result is literally 3D to the viewer? so moving the viewer's head changes what the image in front of him looks like? I've seen that done before with motion controls, so that the game knows where the viewer's head is:

https://www.youtube.com/watch?v=Jd3-eiid-Uw" data-time="
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Sahuagin posted...

that's like saying "using the same technique as real photographs, not just using a 2d image". are you looking for a full light-ray simulation or something? you could maybe do holographic ray-tracing, where you generate ray-tracing results from multiple perspectives. the result would have to be a gif or like one of those 360 degree videos or something.

Consider reflections in games. The easiest way to do them is to clone the terrain and flip it on the other side of the mirror.... very VERY few (virtually none) do reflections via radiosity.
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Lokarin posted...

Consider reflections in games. The easiest way to do them is to clone the terrain and flip it on the other side of the mirror.... very VERY few (virtually none) do reflections via radiosity.

when you say "radiosity" are you using that term to mean something specific or you're just using words that sound vaguely like what you're trying to describe?

"cloning the terrain" doesn't really sound like the right way to describe a reflection effect (it's close I guess). I haven't implemented a reflection before but it would I think use the same geometry with some kind of geometrical transformation applied, so that you'd see the same thing from a different angle, and then it would be rendered to a sub-region of the screen.

it sounds like maybe you're asking for real-time ray tracing? at some point it starts to be "six of one, half dozen of the other". 3d rendering works by (very roughly speaking) transforming models and drawing them on to a 2d surface, keeping track of whether the pixels being drawn should or should not be drawn on top of the previous pixels (z-buffering).

ray-tracing sort of works in reverse: for each pixel in the resulting image, figure out what color it should be by following the path a light ray would have taken to get there, keeping track of everything that was hit along the way, and using various math formulas to compute how they should affect the color. if a ray cast from the pixel immediately hits a red object, then it should be red. if it goes off into space, then it should be the background. etc.

ray tracing is traditionally very slow, though if you google it you can find some modern examples of real-time ray tracing:

https://www.youtube.com/watch?v=J3ue35ago3Y" data-time="

I guess basically you need to be more specific
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Sahuagin posted...

when you say "radiosity" are you using that term to mean something specific or you're just using words that sound vaguely like what you're trying to describe?

https://en.wikipedia.org/wiki/Radiosity_(computer_graphics)
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Lokarin posted...

https://en.wikipedia.org/wiki/Radiosity_(computer_graphics)

yes, I was reading that, but it seems to be just one particular lighting algorithm that doesn't have anything to do with holograms.

so, I guess you're asking for a full light-simulation including having a holographic material in the scene that will appear holographic to the game character (which is possible only via the full light-sim)? (and it would not be holographic to the external viewer?)
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No, radiosity has nothing to do with holograms... it has to do with reflections, which I was making analogy to
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well I can't figure out what you're specifically asking for. depending what you mean, the answer could be anywhere from "3d games already do that" to "that's impossible to compute in real-time".
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well, what I mean is that I want to get a fake 3d effect from using only 3 (or more) lightmaps INSTEAD of just putting a 3d model in a cube
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Lokarin posted...

well, what I mean is that I want to get a fake 3d effect from using only 3 (or more) lightmaps INSTEAD of just putting a 3d model in a cube

if you want to do something like have a bunch of textures, which are all the different ways of seeing the hologram, and then render the particular texture to the flat surface depending on the angle between the camera and the surface, that would be "very easy" to do.
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doesn't battlefront 2 already do that with the character selection?

or they used to
then people started bitching about the scan lines
that made me so tight

RoboXgp89 posted...

doesn't battlefront 2 already do that with the character selection?

or they used to
then people started bitching about the scan lines
that made me so tight

Not sure, I never played Battlefront 2
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Portal 2 does this by rendering the scene from a different angle and culling it to the viewport you can see through the portal.

If you actually want combine light diffusion you would probably have to find a way to combine the scenes so they can share the light diffusion. How you want to do that depends on if you're working with baked lighting or dynamic. They would also have to follow the rules of your viewport, and that sounds like some specific functionality you would have to code into the game engine itself.

You have a very specific definition of a "hologram in a video game" that involves illumination by light diffusion exclusively.

3D bitmaps are a thing, too. Those have been a thing for a while, that might fit your definition of a 'holographic texture'.
https://www.virtual-lands-3d.com/assets/images/articles/displacement-tests.jpg