some general questions about creating filters

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brynn
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some general questions about creating filters

Postby brynn » Mon Nov 22, 2010 1:02 am

Hi Friends,
Here and there I've tried to learn how to make a filter, with mostly poor results. I know that some instructional material is available, but I seem to be lacking in some certain knowledge that might allow me to understand it better. But I have no way of knowing what I'm missing :? :shock:

  1. One thing that's confusing is that some filters look very different on different shapes -- so that while they might look great on a 0.25 x 4 inch rectangle, they look nothing like it on a 2 x 3 inch rectangle. Some look great on large shapes, but icky on text, and vice versa. Or they might look great on a half inch object, but awful on a 3 inch object, or vice versa.

    Here's a screen shot to illustrate:
    Image
    #2, 4, 6, 9 and 10 are all the Non-Realistic 3d Shaders: Chrome filter. Maybe the term "non-realistic" should be my clue, lol. But # 6 and 4 actually do look like realistic chrome, while #2, 9 and 10 really aren't close.

    1.a. At first I was guessing that the difference had to do with distortion as if they had been scaled. But #7 is actually #2 scaled down to the height of #5 and 6, and appears actually less "distorted"
  2. What are the Filter General Settings? No matter where I place a filter on the canvas, or on what object, or where the object is or what it's size, the Coordinates and Dimensions settings never change. And they're the same for everything I apply a filter to, any filter. I have tried changing those settings once I've applied a filter, and changes are apparent on that object or filter at that time. But for example, the Coordinates and Dimensions values are identical for objects 2, 4, 6 and 9. The values for Coord. is -0.25 and Dim is 1.50. And if I draw a large square 2 inche above these objects, and use the 3d Wood filter, the values are the same!
  3. Probably the MOST frustrating thing for me is where to draw those connecting lines. I know the first one goes horizontally from the first primitive to Source Graphic. But after that, I don't know how to use that part of the editor. In most if not all filters, one of the latter primitives line is drawn up to connect to a primitive 2 or 3 levels up. Or sometimes this happens twice (or maybe more presumably), with different primitives, or sometimes another horizontal line is drawn back over to Source Graphic.

    One thing I've been doing to study how they're made, is to recreate existing filters by going back and forth from an existing filter to my new one, making sure I have the exact same settings in my new one, and watching how the filter develops. I just can't figure out how the creator knew where to draw these lines, or which primitive to connect together. If it's altogether trial and error, it's no wonder what I've noticed in #1 above, where different sized or shaped objects look differently with the same filter applied! But seriously what do these connecting lines represent, and how should they be used?

Thank you very much for any help.
All best :D

chriswww
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Re: some general questions about creating filters

Postby chriswww » Tue Nov 30, 2010 8:49 am

from my short experience playing with the inkscape filters, they work best with objects approx 100 pixels or bigger. later scaling the result down doesn't look too bad, still much better than applying the filter to 10 pixels object. i played with the general filter setting for x/y scale, but applies to all effects of the filter equally, so not really usable in that respect. from my past experience playing with povray raytracer, in that you could scale any filter/texture, separately from scaling an object.

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brynn
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Re: some general questions about creating filters

Postby brynn » Fri Dec 10, 2010 5:11 am

bump: ivan?

ivan louette
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Re: some general questions about creating filters

Postby ivan louette » Fri Dec 10, 2010 8:15 am

Hi Brynn,

I will try to reply more in depth tomorrow or next days because I am a little bit sick at the moment. We lack definitely a filters resizing tool, that's right and I am waiting for that too !

On the other hand, do you compile Inkscape 0.48 devel ? If you do it you will find some new custom filters there are already a bunch of them regrouped into an "Experimental" submenu. Soon the "Non realistic shaders" will be grouped in only one customizable filter. I will ask Nicolas Dufour (who makes the custom filters UI's) if we could technically introduce a resizing tool at this level but I am not sure. For me the best should be if this tool was placed in the Filters Editor or in the Stroke and Fill dialogs. The same is true for rotating and squeezing filters.

ivan

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brynn
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Re: some general questions about creating filters

Postby brynn » Fri Dec 10, 2010 8:43 am

Thanks ivan :D

No rush. I actually have a bit of a head cold myself :(

ivan louette
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Re: some general questions about creating filters

Postby ivan louette » Tue Dec 14, 2010 10:03 am

For those who want test them here are the new "Non realistic shaders".

They are a little bit heavier to handle for the hardware... but they include some novelties like the ability to be filled (by the Flood primitive). Most adjustment to the shapes sizes should be made by the two blurs, the first one for the effect size and the second one for the fill blur.

In next time they will be grouped in only one custom filter.

Have fun !

ivan
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