[Scilab-Dev] SEP #16: anti-aliasing

[François Vogel]

Hi,

Having AA activation control in Scilab sounds like a very good idea.

Some comments from my side:

- I think you should state explicitly that you are talking about 
hardware AA, and you are not implementing oversampling and filtering 
of the figures at the Scilab software level. You are merely using the 
AA feature of the graphics board. Thus AA levels will depend on the 
capability of the graphics board the user has. This may sound obvious 
to you, but stating it clearly will not hurt.


- You will have to check for graphics board capabilities when setting 
the AA level requested by the user. For instance the hardware 
configuration I'm running right now only has 2x, 4x and 6x but not 8x. 
Warnings should be written in the console when the user requested 
level of AA is not available from the hardware, and proper fallback be 
used.


- In SEP#16 you say:
"A property “anti_aliasing” will be added to figure handles. This 
property value can be one of the following: “off”, “2x”, “4x”, “8x”, 
“16x”. If the property is set to “off”, anti-aliasing is disabled. 
Otherwise, the value stands for the anti-aliasing quality.
An other approach would be to have only two or three possible values, 
more understandable by the user. The value could be chosen between 
“off” or “on” (actually setting quality to “4x”) or between “off”, 
“performance” (quality “4x”) and “quality” (quality “8x”).
"

I'm strongly in favor of the first option. If a user has enough 
knowledge in graphics to know what is anti-aliasing (and especially 
FSAA) and to use this feature, then this user must also know how this 
works (oversampling 4x == 4 sub-pixels and so on) and that this 
feature can be adjusted to different levels.
Naming the AA levels "quality" or performance" or whatever would just 
add to the confusion. Everybody calls this 2x, 4x, 8x etc, why would 
Scilab have its own different names?
The tradeoff between AA level and graphics performance is real but 
should be reminded in the help page for the new property (help figure?).


- FSAA (multisampling) has no effect on texture aliasing. What about 
providing access to anisotropic filtering at the same time? Textures 
in 3D views would look better (hem... I can't remember: is it possible 
to apply textures on a mesh at all in Scilab? Right now I'm not sure 
anymore)


Francois


Jean-Baptiste Silvy said on 18/02/2009 09:43:
> Hello,
> 
> We've just added a new SEP describing how anti-aliasing can be
> introduced to enhance Scilab graphics.
> 
> SEP #16 is located in the SEP folder of the git master branch.
> 
> All questions and comments are highly welcomed.
> 
> Jean-Baptiste Silvy
> 
> 
> 
>