Re: Merging CSS Shaders proposal into Filter Effects

From: "Tab Atkins Jr." <jackalmage@gmail.com<mailto:jackalmage@gmail.com>>
Date: Fri, 4 Nov 2011 00:43:39 -0700
To: Robert O'Callahan <robert@ocallahan.org<mailto:robert@ocallahan.org>>
Cc: Dean Jackson <dino@apple.com<mailto:dino@apple.com>>, Chris Lilley <chris@w3.org<mailto:chris@w3.org>>, Adobe Systems <vhardy@adobe.com<mailto:vhardy@adobe.com>>, Patrick Dengler <patd@microsoft.com<mailto:patd@microsoft.com>>, Dirk Schulze <vbs85@gmx.de<mailto:vbs85@gmx.de>>, "public-fx@w3.org<mailto:public-fx@w3.org>" <public-fx@w3.org<mailto:public-fx@w3.org>>
Subject: Re: Merging CSS Shaders proposal into Filter Effects

On Fri, Nov 4, 2011 at 12:27 AM, Robert O'Callahan <robert@ocallahan.org<mailto:robert@ocallahan.org>> wrote:
One crazy idea I just had to implement event coordinate transformation:
create a 256x256 texture, set each pixel's R value to the X coordinate and G
value to the Y coordinate, apply the vertex shader with an identity fragment
shader, and save the result. To transform an event coordinate, extract from
the result the color value at the pixel you care about, and recover the
original X and Y values from the R and G channels.

That's not so crazy.  I think Greg Tavares had the same idea.

This was discussed during yesterday's FX F2F and Johannes Behr talked about approaches with picking shaders that use the R/G/B channels to store picking information. He showed a demo during the break. From your and Johannes' description, it seems to be similar. I have cced Johannes so that he can comment. I have an action to further research this and add a proposal to the spec.

Vincent