outer glow

Jan 13, 2009 at 12:44 PM
Edited Jan 13, 2009 at 12:44 PM
Hi there,

Is there any technical reason why this library doesn't include outerglow?
I mean, I don't want to push anyone to do it, I'm very very grateful for all this stuff but I've being looking for this shader effect over the net and I can't find it. So before I try to do it by myself I'd like to know if there is any kind of trouble or limitation.

Thanks in advance.
Jan 13, 2009 at 7:24 PM
Hi I don't have the answer to your question but,
you can almost have the same effect with the Drop Shadow effect, if you just set direction or distance to zero.
Jan 13, 2009 at 8:29 PM
The fact is that a full-blown outer-glow (as was available in the first WPF release) is not really doable with what we have currently access to in the WPF Effect API.
Even the WPF built-in DropShadow and Blur are "hacks". They are implemented using direct calls to milcore in order to implement a multipass effect.
The public API only lets you write a single-pass shader to build your effect, and that's a hard limitation when it comes to effects such as OuterGlow, DropShadow or Blur.

As Mo0gles wrote, you should try to get away faking the outer glow with a Drop Shadow having distance = 0. It's not as flexible but at least it works now.
Jan 14, 2009 at 9:14 AM
I had already tried the shadow hack but does not fit what I need.
So, the limitation is that the shader can do only 1 pass. Ok, I'm gonna try to acumulate effects, one for each pass.

Thank you so much.
Nov 15, 2009 at 8:10 PM


Did you managed to do outerglow using shaders?

Thank you!