[Bf-committers] NDC (Normalized Device Coordinates) in Render Nodes (was: Render Layers and render size problems (50%, 25%, ...) to be addressed in 2.5?)

[Dalai Felinto]

Hello,
inspired by the Winter Camp I decided to bring this topic back.

Matt (aka broken) told in IRC that a better design for dealing with
coordinates in the Compositor, UV mapping, ... would be implementing NDC
(Normalized Device Coordinates).

He even has a lot of thoughts on this subject:
http://wiki.blender.org/index.php/User:Broken/BreakingRenderCompatibility#Compositor

Mainly we would be using 0.0 to 1.0 as relative values to crop, offsetting,
blurring (radius), ... That way we would have way more consistent results
between the preview renders (25%, 50%) and the final one (100%).
The side-effect is loosing back-compatibility with old files :/

Matt, are you planning to bring this to the table during Winter Camp ?

Cheers,
Dalai

2009/1/12 Roger Wickes <rogerwickes at yahoo.com>

> Well, if the input image is different from the render resolution, there is
> a two step issue the compositor has to face. 1) if the input image is higher
> res than the output, but the aspect ratios are different, the input has to
> be cropped or stretched. If cropped, then it is arbitrary and up to the
> compostior to choose an area of the input image that makes it into the final
> render. 2) if the input image is smaller resolution, then the image has to
> be letterboxed which presently is completely automatic - :) or translated so
> it is an element over another image.
>
> Presently, the Scale node, when Absolute is chosen, uses the Render
> settings and scales the image to the "proper" resolution.  There is a Screen
> Size % option, but I cant figure it out :( Either way, it's a human
> decision.
>
> I *would* like the image node to give you resolution info about the image,
> like the texture panel does.
>
> ----------------
> Sent by Roger Wickes for intended recipient. If you are not the intended
> recipient, please delete this message and contact Mr. Wickes immediately.
>
> ------------------------------
> *From:* Dalai Felinto <dfelinto at gmail.com>
> *To:* bf-blender developers <bf-committers at blender.org>
> *Sent:* Sunday, January 11, 2009 11:02:29 PM
> *Subject:* [Bf-committers] Render Layers and render size problems (50%,
> 25%, ...) to be addressed in 2.5?
>
> Hello,
>
> As some of you may know, the Render Layer system always use absolute
> values for its tools.
>
> For example, if you use a Crop node cutting half of the image, once
> you change the render size to 50%, the result will be completely
> different.
> The same problem happens with Translate node, and when you use an
> external image as Input (according to the size of the render,
> different parts of the image will be displayed). I guess Blur node is
> also affected by this (the scale of the blur radius).
>
> I'm not familiar with the Render Nodes code, but it looks like we
> would need to use a transformation factor (0.5, 0.25,...) relative to
> the render size *everytime* we are using absolute values (or at least
> in the cases above).
>
> The reason I'm writing it, it's because I'm wondering if this is the
> kind of think that could/should be solved while porting render nodes
> to 2.5. Specially if the solution may be structural, it could avoid
> re-work later.
>
> Sorry if this is not priority or the focus of 2.5 now, but I felt like
> writing :)
>
> Cheers,
> Dalai
> http://blenderecia.orgfree.com
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