"Scroll" or "offset" the cubemap ...

Questions & Answers
1

Here’s one …

Imagine a shiny car with a cubemap sky. You see the “clouds” on the car.

The car and the camera are simply static.

Now, I want the clouds to move over the surface.

How the heck would you do that? You really can’t “offset” a cubemap. Is there a way?

Essentially, I want to scroll the top image of the cubemap (or perhaps all four of them on the tunnel sides). In this way, it would look like the clouds (say) are moving along.

      • Somewhat related issue:

grab the car and tumble it on it’s x axis (or indeed, just move the camera around)

The way a cubemap is rendered on an object depends on the bearing of the camera to the object.

I guess there’s essentially a quat that gives that relationship.

So with the camera and object static… how can I manually 'scroll" that relationship??

(TBC, this would make it look as is if the distant world was “tumbling around” the car - even though the car was sitting still.) {Could be very useful for eg. space effects etc.}

To be concrete, in both these questions, say we’re using everyday Reflective/Bumped Diffuse

Again, what I really wanna do is part A … in a word, scroll some clouds (or whatever) over the surface.

(I have to believe this is a fairly common need ??)

Cheers!!! PS pls don’t mention renderToCubemap in this :slight_smile:

caption contest …

4482-box.jpg

“where the hell are the offset fields?”

2

I don’t think that’s possible since you can’t scroll a cube map even when it consits only of tilable textures because 3 textures meets in one corner. reflection mapping is ment for “static” reflections.

If you want to “fake” this effect it’s probably easier to write a simple shader that maps another cloud texture onto your car ;). Could be done as detail map or in screen space. See image 5 and 6. It might a bit tricky to make it look like a reflection.

btw, by the camera and the car are “static”, do you mean they stay in position but can rotate or are really static?