View Full Version : Blurry glowing halo effects on objects

09-14-2009, 01:50 PM
How do you get a halo kind of effect on an object like a cube or other object?

Here is an example and probably not even opengl but I like the effect. The lines and some of the objects in the screen are "blurred" to give a kind of glowing/halo effect.


Ilian Dinev
09-14-2009, 01:53 PM
It doesn't need any special post-processing, there they just use pre-blurred RGBA textures.

09-14-2009, 03:52 PM
This looks more like screenspace blur as postprocess.
glCopyTexSubImage gets data from framebuffer to a texture.
Sample texture with a blur shader.
Draw fullscreen quad with additive transparency.

09-14-2009, 04:48 PM
i have to agree with Ilian here, those are just pre blured textures with some form of alpha blending, they aren't even filtered, i would use (GL_ONE,GL_ONE) blending, it gives the most bang for the buck.
Also you have to remember that this is probably for a iPhone game, so one cant use all the latest stuff in there.

09-15-2009, 07:48 AM
Yep, note that each object has it's own unique blur radius. So there is no effect or postprocessing here. Objects are just blurred textures.

09-16-2009, 06:11 PM
You can perform a convolution (or separable convolution) by feeding the image back into a texture with multiple taps (render to texture helps here), however there are simpler cheaper ways depending on your application, as everyone has already said the example shown could easily be done by adjusting the content to include a glow effect in the textures used and applying a suitable blend function to accumulate it during rendering.