[GEM-dev] alpha blending of patterns

[IOhannes m zmoelnig]

Conor Higgins wrote:
> Hi I am having a slight problem and cant seem to find the remedy for  
> it just yet...
> 
> What I am doing is creating an optical illusion system for an artist.  
> The idea is that when the person is moving then they will appear in  
> the pattern as a silhouette, but will have a pattern on them, and when  
> their movement is minimal then they will disappear into the canvas  
> again. It is a simple idea but there is one thing catching me out.
> 
> I am trying to map a pattern to just the colour black but alas am  
> having no good results. Has anyone got an idea of how to just overlay  
> on a single colour?
> 

e.g. use [pix_movement] to convert frame-differences into RGBA 
(obviously in RGBA colorspace) and [pix_takealpha] to use this 
alpha-mask for your pattern-image to do the blending.

fgamsdr
IOhannes