Fixed Backgroud Image

Unity Engine
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1

I am pretty ignorant when it comes to writing shaders (amongst other things…) so this might be an easy one (then again it might not be…)-
How do I use a fixed background image that is :

  • unaffected by camera movement and orthographic size
    (for an orthographic camera) or if it is impossible for a perspective camera.

  • only one pass ,
    when I use skybox , it uses 6 passes when I only need a fixed image , when I try to modify the Skybox shader to remove the remaining textures I get psychedelic smears on the iphone (pretty cool ones I might add…)
    :shock:

2

The rig I’m using for now is:

  • make a new plane a child of your camera
  • rotate it to face the camera
  • move it as far as needed from the camera
  • scale it to fill the camera view
  • apply a "self-illum/Difuse"material containing your image

When the camera is rotated the plane moves with it.

This is far from perfect because of the following reasons:

  • the image quality is pretty bad. I guess it’s due to the non-pixel perfect scaling
  • if you zoom your camera dynamically then no good
  • I’m not sure you can change the image dynamically (but I’m quite new to Unity so it might still be possible after all)

If someone has a better solution I would use it gladly.

3

Thanks Arrakis, that’s pretty much what I’m doing , but The reason I would prefer to use a skybox is to avoid the clear camera phase and clear directly to the image.
Every draw call matters when it comes to the iphone.