[PD] Possible to mask a rectangle with a rectangle using GEM?
ch at chnry.net
Sat Jun 12 09:25:14 CEST 2010
i may have misunderstood the question, because i think there is a much simple solution using rendering order.
Le 12/06/2010 07:05, patko a écrit :
> hi again,
> after reflexion, I don't think it's a good idea to snap and apply alpha
> when you want to apply a texture on the outer rectangle, some pixels might
> disappear when they have the same amount of color that is supposed to disappear on the masking process.
> It might be possible to apply a texture mapping on vertices drawn with openGL functions rather,
> but I've no clue about how it could be done yet.
> Or just use the method proposed by jack that is about using four rectangles if you don't use a texture, you can connect them together like this:
> [translateXYZ -1 0 0]
> [rectangle 0.2 1]
> [translateXYZ 0.8 1 0]
> [rectangle 1 0.2]
> Just loading an image containing the alpha hole, like attached would be cpu wise, very simple to do with an image editor,
> and wouldn't add artefacts on your texture.
> I've attached an example patch and the gimp image, on gimp just draw the two rectangles, select the inner rectangle, go to Colors menu,
> and then choose "Color to alpha".
> I've choosen the tiff format because it works on most platforms, unlike png.
> Patrice Colet - 06 32 66 03 57
> ----- "Jack"<jack at rybn.org> a écrit :
>> You have several possibilities to do what you are looking for :
>> - use (as Patrick describe) two rectangles to create a mask (with
>> [gemframebuffer], [pix_snap] and [pix_buffer], [pix_buffer_read],
>> [pix_buffer_write]) then [pix_mask] or [pix_multiply];
>> - use four [rectangle]s to build 'lines' of the rectangle;
>> - use GLSL to create the mask and the final image.
>> Surely, there are other ways (like openGL objects with GEM for
>> See in help> browser> examples> GEM (in Pd-extended) to understand
>> what this objects do.
>> Hope that helps somewhat.
>> Le vendredi 11 juin 2010 à 10:03 -0700, Ryan Trigg a écrit :
>>> Thanks for your reply, sounds like interesting options (especially
>>> snapping two rectangles together)...could you be more specific with
>>> instructions on what objects to use? Pardon my novice GEM skills.
>>> On Fri, Jun 11, 2010 at 9:49 AM, patko<colet.patrice at free.fr>
>>> you can put an image texture with a rectangle made of
>>> or draw an alpha rectangle using gridflow and then load
>>> as a texture
>>> with #to_pix,
>>> or snap two rectangles with different colors,
>>> and turn to alpha all pixels matching the inner rectangle.
>>> Patrice Colet - 06 32 66 03 57
>>> ----- "Ryan Trigg"<ryan.trigg at gmail.com> a écrit :
>>> > I am trying to mask [rectangle] using GEM with another
>>> > [rectangle] (that controls the first rectangle's alpha
>>> > it is placed) in order to create an adjustable rectangle
>>> outline (that
>>> > has a border of my desired thickness). I noticed that you
>>> can choose
>>> > [draw line( and [width $1( for a rectangle but the
>>> > of the line is much too small. Does anyone have any
>>> or ideas?
>>> > Or maybe there's an object like [disk] (using 4 segments)
>>> but with the
>>> > ability to adjust the height and width just like
>>> > Cheers!
>>> > Ryan
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