I'm trying to make the effect of random flickering triangles.
For exampe i have a layer with grid of triangles (or another pattern)
and bottom layer with fractal noise. And i need to take the lightness of BG layer to triangles.
Triangles must be flat shaded.
Is any one know how to do this? Or maybe there's a simpler way?
I'm having a hard time understanding what you're trying to do but I'll take a stab at it. It sounds like you can use a Track Matte (luma matte) to get the effect you're after. So you'll want to do the following:
1: place your fractal noise layer above the triangles (or other pattern) 2: set the triangle layer to 'Luma Matte' under 'TrkMat' in the timeline.
If you can't see that option in your timeline, try pressing 'Toggle Switches / Modes' at the bottom of the timeline and it should reveal that property.