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slowly changing noise

Unread postPosted: Wed Aug 12, 2020 3:46 am
by bvz2000
Is there a way to generate slowly changing noise?

I.e. I want a light to dance around a bit as though it were a candle flame. I have been using this function in the translate x field. But it changes too rapidly (i.e. I am getting a true random noise it appears when I want a slowly modulating noise).

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I'm afraid that my math skills aren't up to figuring out how I could smooth out a noise function so that the light source slowly moves from one point to the next vs. jumping around frame to frame.

(Bonus question: I am controlling the light intensity based on a sample image of a real fire - a sequence of images. Could I somehow reference the intensity of a pixel in this map to control the translate values for the light?)

Re: slowly changing noise

Unread postPosted: Wed Aug 12, 2020 9:58 am
by dcourtois
You want something like this:

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multiplier = 0.1;
cellnoise(T * 0.1)

Just make multiplier lower to slow down even more.
Also, F is the frame number, and T is the time in second (e.g. if your scene is setup at 24 FPS, if F == 12, T == 0.5, so it's usually easier to use T for slowly varying stuff)