11 replies to this topic

[starstutter]

Hi, I have been googling a simple question that so far doesn't really appear to have an answer (well a straight forward one anyway), and part of the problem is that I need specific commands.

Is there a way to render just a normal scene to a regular 2D render target, than take that render target and copy it to a "slice" of a volumetric texture in directX 9? If so, what are the steps to follow. I need the functions specificly, since volume textures seem to make no reference to regular 2D surfaces, such as GetSurfaceLevel().

Also, locking the volume texture itself and transfering pixel-by-pixel is not an option I'm afraid. The target framerate for this is about 40 fps, anything less would be unacceptable.

Thanks in advance.

EDIT: also, I don't think this is possible, but are you able to take a slice of a volume texture and directly make it a render target? I know there's a way to in DX10, but I'm not using that.

[XVincentX]

I tried to make a deep research in documentation, but i did not found nothing that can help you.
You should try asking at official XNA forum.

[Goz]

TBH I had a look at it too and I just couldn't see any way to do it as you require. Would be easy using a Texture Array under DX10 ... but thats not much help, alas :(

[starstutter]

**sigh**
Well, thanks anyway guys

[Kenneth Gorking]

Does it have to be a volume texture? Couldn't you use a series of 2D textures instead?

[starstutter]

could you expand on that? My target resolution is 64x64x64. Are you suggesting I have an array of 64 textures? I guess that would be fine for resource management but how on earth would I make use of that in the shader? There are no shader-based texture arrays in DX 9 of course.

Thanks for any advice.

EDIT: wait, I just got an idea and maybe this is what you were saying. I could place the 64 (64x64) slices on a single 512x512 texture! Each one coule be treated like its own texture using rect bounds and careful control of UV coordinates.
:D
This just might work! Thank you so much! (whether you meant to say that or not :) )

[Reedbeta]

Even easier to use a 4096x64 texture, if your card lets you use dimensions that large. Also, you of course won't get any filtering along the texture 'z' axis this way, unless you do it yourself, but I assume you already considered that.

[starstutter]

Reedbeta said:

Even easier to use a 4096x64 texture, if your card lets you use dimensions that large.

yup, it does, but I perfer to keep the dimentions even and powers of 2 whenever possible (at least I'm told its faster). Plus, according to most its just good practice.

Quote

Also, you of course won't get any filtering along the texture 'z' axis this way, unless you do it yourself, but I assume you already considered that. :)

Well, no free filtering anyway. I can always manually interpolate the texels. Its not nearly as fast of course but I'm so thrilled that I actually found a way I couldn't care less =D

[Kenneth Gorking]

Yeah that was what I meant, glad to see you pieced it together from my sparse comment :)

I don't now if POW2 textures are faster anymore (and I couldn't care less about 'good practice'), but managing the UV coordinates are simpler when using a 4096x64 texture.

Either way, good luck

[Reedbeta]

starstutter said:

yup, it does, but I perfer to keep the dimentions even and powers of 2 whenever possible

4096 and 64 are powers of two. I don't think there's any speedup involved with using a square texture over a rectangular one, though.

[JarkkoL]

Beaware of filtering issues in the horizontal edges of the images if you go with 4096x64 texture and that it doesn't tile horizontally like volume textures either. Might not be an issue in your case though.

[starstutter]

Reedbeta said:

4096 and 64 are powers of two. ;) I don't think there's any speedup involved with using a square texture over a rectangular one, though.

hmm, didn't know that actually, thanks. Now its looking like a good option.

JarkkoL said:

Beaware of filtering issues in the horizontal edges of the images if you go with 4096x64 texture and that it doesn't tile horizontally like volume textures either. Might not be an issue in your case though.

Nope, and come to think of it actually, that may be a good thing. The lack of filtering across z slices though is still a downer, but can be easily fixed.