[Bf-committers] water painting

[Robert Wenzlaff]

On Friday 26 November 2004 13:51, Jeremy Wall wrote:

> implemented as a rendering plugin it makes sense. blender already has
> toon style and traditional raytracing renders why not a watercolor
> style. or as a postprocess plugin for the compositor which would
> probably fit the code he wrote better.

Toon is a shader because Toon needs to be a shader.

 Toon shading is a 3D effect, even if it tends to obscure the 3D data with 
minimalistic shading.  It still uses the 3D data to calculate that effect and 
thus could not be implimented as a sequence plug-in.

As I understand it, the watercolor effect being spoke of is a 2D effect. 
Not only does the watercolor effect not use 3D info, I'm not sure it can be 
implimented as a shader.  A shader does not determine the color of a pixel 
directly.  Shaders determine what each object's color is at a given vector 
from the lights/camera.  The pixel is then colored with a weighted average of 
all the objects that intersect there.   

Color boundaries would bleed in watercolor reguardless of their object's 
separation on the Z axis.  This bleed is done on a pixel to pixel basis 
without reguard to where the object is in the scene.  There is no mechanism* 
in the shading system to allow an object to effect the color of a pixel that 
does not intersect the object.  You would end up with a nice, photo sharp 3D 
scene where it looked like all the objects were covered in watercolor....

Anyway, it can be done now as a sequence plugin.  I've always thought that a 
single image (or single + static image(s)) sequence plugin should be allowed 
to be specified as a post-process.  This would make things like zblur much 
easier to use.

*OK, Radiosity does this (and glow effects if we ever get them), but it  is 
still a 3D effect (volume based), and requires a lot of special code.  Why 
add a lot of special code to the 3D shading tree, when the watercolor effect 
can be done so simply in 2D?
-- 
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Robert Wenzlaff                  rwenzlaff at soylent-green.com