Comments on: (Shader Library) Cross Stitching Post Processing Filter in GLSL

By: errric

errric — Fri, 21 Sep 2012 16:21:03 +0000

What would the code be if i don’t want to use rt_w and rt_h? i want to apply on whole image, not half. How can i do this, please help.

By: kaoD

kaoD — Wed, 14 Dec 2011 21:09:24 +0000

I see all your shaders are full of branches. You may not be aware of it, but branching is extremely expensive in GPUs. You should consider (if you care about performance, which you may not) using mix and step for “branching”.

By: JeGX

JeGX — Tue, 26 Apr 2011 07:03:10 +0000

@Nathan: sorry for the delay in my replay.

time uniform is not used, it’s only the result of some copy/paste operations 😉

“invert” is initialized by the Lua script in the GeeXLab demo (see the complete source code).

rt_w and rt_h are the dimensions of the render target, here the size of the demo (1024×576). Both variables are GeeXLab built-in uniforms.

By: Nathan

Nathan — Thu, 21 Apr 2011 09:04:45 +0000

I’m trying to convert this into HLSL and I’m a little confused at some of the values used.

You send over “time”, but it is never used. Was this intentional? Does it have a use?

You initialise “invert” to be 0, but then check if it is 1. I’m not familiar with GLSL, but I’m presuming you would have to send the value 1 over to the shader under certain circumstances? What would these be?

There’s probably a naming convention I’m unaware of, but what do rt_w and rt_h stand for?

By: Korvin77

Korvin77 — Sat, 09 Apr 2011 00:44:28 +0000

it looks cool! I didnt even know about PixelBender, thanks for remembering