Smoke Environment

Medo Mex · 2013-04-21T08:35:17

I'm creating a smoke environment, I notice a problem when the smoke particles intersect the terrain. [attachment=14960:smoke env.png] How do I fix it?

Graphics and GPU Programming Programming

Started by Medo Mex April 18, 2013 07:56 AM

13 comments, last by L. Spiro 11 years ago

ATEFred

1,700

April 19, 2013 06:19 AM

In D3D9, you can't use (normal) depth buffers as textures (readable), only as surfaces (writable).

One workaround is to use MRT during your normal rendering, and manually write depth to a second render target. This however, requires editing all our shaders, and is inefficient.

Another workaround (that I'd recommend) is to create an "INTZ" texutre. This texture is a readable depth texture, and you can get its surface in order to use it as your depth/stencil target (instead of your regular depth buffer).
The only downside to this approach is that creating an INTZ texture will fail on any GPU older than a GeForce 8, so it raises your minimum requirements.

If I remember correctly from back then, you can use RawZ on older NV gpus.

Medo Mex

891

Author

April 21, 2013 04:57 AM

I'm still a bit confused.

Do I have to use the pixel shader directly when rendering the particles?

Or do I have to get the depth information with the fixed functions and then pass it to the pixel shader?

L. Spiro

25,818

April 21, 2013 05:35 AM

The depth values are stored in a texture which your pixel shader will access.

L. Spiro

I restore Nintendo 64 video-game OST’s into HD! https://www.youtube.com/channel/UCCtX_wedtZ5BoyQBXEhnVZw/playlists?view=1&sort=lad&flow=grid

Medo Mex

891

Author

April 21, 2013 06:54 AM

@L. Spiro: Any code sample for creating depth buffer texture in D3D9?

Also, I want a pixel shader example for soft particles, I have checked some links but couldn't find a complete sample.

L. Spiro

25,818

April 21, 2013 08:35 AM

There are no code samples because this is extremely dependent on your engine.

Hodgman mentioned the valid point that writing depth to a special texture other than the main depth surface (which normally cannot be read) requires all shaders be modified to write that information, which really will be quite a nuisance when you have a ton of basic shaders that all have to be hand-written.

My engine’s shader system works on permutations based on macros within a single shader, so for me to add this tactic (which is what I did) is nothing.

If you want to do something similar it will really take a huge amount of work and you have to really focus your shader system on a macro-based system. Macros help with permutations, obviously. But implementing your own system really takes a lot of work, and getting to the point where you can use macros may require a whole rewrite of your shader system.

So it is up to you how to proceed.

L. Spiro

I restore Nintendo 64 video-game OST’s into HD! https://www.youtube.com/channel/UCCtX_wedtZ5BoyQBXEhnVZw/playlists?view=1&sort=lad&flow=grid

Smoke Environment

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