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Drawing Effects Past The Viewport

Posted: Thu Jun 03, 2021 11:29 am
by Zetboi
Heyas!
I've been experimenting a whole bunch with things for a while now, but I always find that if I want an effect to do something specifically off my viewport, the effect stops drawing. So the viewport itself isn't just a camera, but a drawing angle?

Here's an example:


This is something simple just for examples sake. It doesn't matter what the effect is, as it applies to any given situation.

In the example, there's an image of a circle with Trails, having a sine moving the Y-axis up and down through a Translate. Very simple.
As the video shows, when I move the image out of the viewport/out of view, it stops drawing the trail, and if I wanted to crop that start image of the circle away, I don't really see any possible solutions to do so.

Now, is it possible to have effects being used out of view?

Re: Drawing Effects Past The Viewport

Posted: Thu Jun 03, 2021 1:15 pm
by Sadler
crop-frame.jpg
crop-frame.jpg (50.46 KiB) Viewed 2477 times

Re: Drawing Effects Past The Viewport

Posted: Thu Jun 03, 2021 3:06 pm
by Zetboi
Sadler wrote:
crop-frame.jpg
Thanks once again Sadler... You and Eric are truly Grandmasters in music visuals ;)
But back to the original question.. Is the viewport just a drawing angle, then? Won't this little trick essentially overwork the GPU if used on basically everything in a scene with multiple inputs? Kinda like the Anti-alias module.

Re: Drawing Effects Past The Viewport

Posted: Thu Jun 03, 2021 5:46 pm
by Sadler
Yes, it does overwork the computer a little and use a bit more memory but I don't think as much as the AntiAlias module. Eric can confirm this with more authority. I imagine the output window as a viewport into another world, especially when dealing with 3D and media greater than the output resolution.

Re: Drawing Effects Past The Viewport

Posted: Fri Jun 04, 2021 4:50 pm
by Magic
Yes I think the analogy of an output window into a world is a good one. Imagine being in a room and you're looking out the window. The world outside is the 3D world with objects in it. But the 2D window itself is important too. Pixels have no meaning in the outside world, but they do have meaning on the window. Everything in the outside world eventually gets represented as pixels on the window. In effect, when you render something, you are tracing the outside 3D world on the 2D window. So the idea of a 2D effect like Trails has no meaning outside the window.

What Sadler suggested is a reasonable way around it, which is to have another window outside. That is, another 2D window in the 3D world. So basically, you're looking through two windows instead of one. Yes, it uses a bit more processing, but there's really no other way to do it.