More than one camera?

To do this you need to render to target. This will save the scene to a texture.
In your case you would do 2 render stages one rendering to say the left side of the target texture and the other to the right. then you simply copy that texture to the back buffer and your done!

You don't need to render to texture. http://www.codesampler.com/dx9src.htm check the viewports demo. Basically, you need to render the scene taking up the whole render space first, then set the viewport to only render into where you want the other camera to render to.

Hth and sorry it's a bit brief :P

You can definetly do it either way. However, I think each is better used in different situations.

Overlayed rendering, where the world is rendered on top of the other render (ie the progress of some vehicle), can best be implemented with render targets. This is because you can render the overlay to a texture, and they render that texture to any place on the screen.

Split-screen rendering (ie multiplayer games), can best be implemented with viewports. This is because the two rendering areas aren't overlapping at all.

Thanks for the help guys. The application is more likely to be using 'windows' from other camera's on top of the normal graphic output, so it looks like render targets are the way forward.

Thanks again.

Mark Coleman

I don't know about DirectX, but I'm pretty sure you'd use the same method as you would in (for instance) openGL.

You can't render to multiple cameras at the same time, you have to render one after the other.

Set the camera parameters up for one camera (including viewport params, like clip region, possibly stencil etc). Then draw your objects.

For each other camera, just do the same thing again. If you're using z-buffering it might be necessary to clear the zbuffer in between (if the regions overlap in the accum. buffer). You'll want to reset the zbuffer params anyway seeing as the different views may want different params.

If you use stencil buffering (if indeed, that's what it's called in DirectX), you can use non-rectangular regions (Example: oval rear-view mirrors)

Mark

Quote:

Original post by circlesoft You can definetly do it either way. However, I think each is better used in different situations. Overlayed rendering, where the world is rendered on top of the other render (ie the progress of some vehicle), can best be implemented with render targets. This is because you can render the overlay to a texture, and they render that texture to any place on the screen. Split-screen rendering (ie multiplayer games), can best be implemented with viewports. This is because the two rendering areas aren't overlapping at all.

Huh? I thought viewports could overlap if you wanted them to, is that not true?

Quote:

Original post by Pipo DeClown Huh? I thought viewports could overlap if you wanted them to, is that not true?

Perhaps you can, I've never really gone in-depth and tried it. However, render targets seem to be much more suited for window-like rendering. For one, I think it's much easier to deal with rendering a texture, than to deal with setting up viewports and such. Also, if you already have render targets set-up, you can apply some cool post-processing effects.

A viewport is pretty trivial to set up and I would be shocked if it had a significantly lower cost that setting a render target, rendering and then copying.

In general I'd say that viewports are the way to go. If however you do want post-processing or if the small image can be cached (only updated occasionally) then a render target would be a better choice.

A render target is definitely the most flexible choice, but whether it's the right one depends on exactly what you want to accomplish.

Quote:

Original post by circlesoft Quote: Original post by Pipo DeClown Huh? I thought viewports could overlap if you wanted them to, is that not true? Perhaps you can, I've never really gone in-depth and tried it.

You can have overlapping viewports.
It's easier to setup but less flexible than mutliple render targets.
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Ok. DH already covered that a few seconds earlier [smile]
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