Use an image as a "flat" backdrop in OpenGL sketch?

Core Library Questions

scmurray

Use an image as a "flat" backdrop in OpenGL sketch?

in Core Library Questions • 2 years ago

In a 2D sketch, it's easy to use a PImage as the background, and have everything drawn on top of it.

I'm doing something in 3D with the OpenGL renderer, which seems to want to position everything in space. Is there way to tell OpenGL to use a PImage as a "flat" backdrop, meaning the image would always render in relationship to the sketch window, while any other elements would render "on top" or "in front" of that, per normal OpenGL/3D rules?

My current workaround is to place the PImage in 3D space, but tweak the camera settings so it looks like it's lined up with the sketch window.

Replies(2)

amnon.owed

Re: Use an image as a "flat" backdrop in OpenGL sketch?

2 years ago

Put this at the beginning of the draw() loop:

hint(DISABLE_DEPTH_TEST);
camera();
image(bg,0,0,width,height);
hint(ENABLE_DEPTH_TEST);
// then do other camera() stuff, draw your 3D shapes etc.

This also works for placing 2D imagery (images, gui, etc.) on top of 3D stuff by the way.

If you have trouble with a 'dark image' in the latter case, then you also need to add noLights();

scmurray

Re: Use an image as a "flat" backdrop in OpenGL sketch?

2 years ago

Perfect! Thank you, Amnon!

I knew it had something to do with depth, but was spacing out on the answer.

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