How to overlay direct3d in directshow

I am looking for a tutorial or documentation on how to overlay direct3d on top of a video (webcam) feed in directshow.

I want to provide a virtual web cam (a virtual device that looks like a web cam to the system (ie. so that it be used where ever a normal webcam could be used like IM video chats)

I want to capture a video feed from a webcam attached to the computer. I want to overlay a 3d model on top of the video feed and provide that as the output.

I had planned on doing this i开发者_开发技巧n directshow only because it looked possible to do this in it. If you have any ideas about possible alternatives, I am all ears.

I am writing c++ using visual studio 2008.

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Use the Video Mixing Renderer Filter to render the video to a texture, then render it to the scene as a full screen quad. After that you can render the rest of the 3D stuff on top and then present the scene.

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Are you after a filter that sits somewhere in the graph that renders D3D stuff over the video?

If so then you need to look at deriving a filter from CTransformFilter. Something like the EZRGB example will give you something to work from. Basically once you have this sorted your filter needs to do the Direct 3D rendering and, literally, insert the resulting image into the direct show stream. Alas you can't render the Direct3D directly to a direct show video frame so you will have to do your rendering then lock the front/back buffer and copy the 3D data out and into the direct show stream. This isn't ideal as it WILL be quite slow (compared to standard D3D rendering) but its the best you can do, to my knowledge.

Edit: In light of your update what you want is quite complicated. You need to create a source filter (You should look at the CPushSource example) to begin with. Once you've done that you will need to register it as a video capture source. Basically you need to do this by using the IFilterMapper2::RegisterFilter call in your DLLRegisterServer function and pass in a class ID of "CLSID_VideoInputDeviceCategory". Adding the Direct3D will be as I stated above.

All round you want to spend as much time reading through the DirectShow samples in the windows SDK and start modifying them to do what YOU want them to do.