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MOnsDaR
New Participant
September 16, 2013

DirectX 9 Integration

I'm currently diving into developing with the Rift. I've got access to a closed source branch of the Arma 1 engine (VBS2) where it is possible to get the D3Device (Doc Link).

I've done my first steps with DirectX, but I can't wrap my head around what I need to do for rendering my scene with different viewports and and applying the shaders.

Are there any open source examples or even tutorials out there, showing how to do that?

I found some topics and projects related to that, but I'm not able to get it all together.

    6 replies

    cybereality
    Inspiring
    September 16, 2013
    What you need to do is render the scene to a frame buffer (render to texture) instead of the back buffer. So you can create one of these for each eye. Then render to them with a different view matrix that is offset to the side (to simulate the spacing between the eyes). You will then want to render these to a full screen quad the size of the screen. Before this step you would run it through a distortion/pre-warp pixel shader. That is one way to do it.
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    Falambo
    New Participant
    March 5, 2014
    I am currently trying to integrate Oculus Rift support into one of my own applications.

    The problem I currently have is that I am unsure how to combine the two Eye Render Targets into one Texture. Should I do that in a pixel shader?
    cybereality
    Inspiring
    March 5, 2014
    You can do that in a pixel shader, it's not that hard.

    You can also just have 2 quads (one for each eye) and that can work as well.
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    owenwp
    Up and Coming
    March 5, 2014
    What you probably want is to use SetViewport. This lets you render into a specific rectangular area.

    Also rendering directly into a texture is not ideal in D3D9, because then you cant use antialiasing. Typically you should render to the backbuffer as usual, then copy the backbuffer to a texture which you can use for your shader.

    I believe the OVR SDK shows how to do all of this.
    Falambo
    New Participant
    March 12, 2014
    Ok thank you for your answers.

    Another question I have is concerning the Direct3D10 distortion pixel shader in the sdk overview document. For a DirectX11 shader I would combine the variables for scaling into a constant buffer and then update the whole thing instead of doing it for each variable individually like in the example, right?
    owenwp
    Up and Coming
    April 17, 2014
    You could, but that isn't really necessary because D3D will automatically make a single constant buffer for all global constants. Doing it explicitly is only important when you have constants that vary at different rates, like per frame vs per object.
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