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Newbie Shader Question on masks.

Discussion in 'Shaders' started by Fluzing, Apr 5, 2014.

  1. Fluzing

    Fluzing

    Joined:
    Apr 5, 2013
    Posts:
    815
    Hi All,

    I am building a space game and I am designing the GUI now for the ship status. I am trying to create a shield status effect (in blue in the picture. As the shield of the ship goes down, the blue line gets thinner. I figured the easiest way to decrease the blue line would be to shrink the scale of a circle. However, if I simply use a circle with a black hole in it, the hole would shrink too.

    I figured a simple mask that cuts out the hole would be the best solution, but is it possible to achieve what I want using a simple mask? How would I do this? I tried finding a way to lay a mask onto a texture, but I can't find anything on this subject. Is what I want possible?

    Below the picture. The hole is supposed to be the same size in both instances.

    $shield.jpg
     
    Fluzing, Apr 5, 2014
    #1

  2. bricevdm

    bricevdm

    Joined:
    Nov 4, 2009
    Posts:
    34
    the easy way would be to do a flip book, where you have various steps of the animation side by side which play like a series of frames.
    Since this is only a circle and you only want to change the outline you could look into "signed distance fields" and create an animated mask by clamping a blurred version of your circle. (this involves some custom shaders tough, but it's not too complicated)
    https://www.youtube.com/watch?v=CGZRHJvJYIg
    http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf
     
    bricevdm, Apr 9, 2014
    #2