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EnigmA Amiga Run 1998 July
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EnigmA AMIGA RUN 29 (1998)(G.R. Edizioni)(IT)[!][issue 1998-07 & 08].iso
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Genlock
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1998-02-17
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Date: Sat, 15 Nov 1997 13:26:51 -0500
From: "Martin J. Conlon" <mconlon@ENGSOC.CARLETON.CA>
Subject: Re: [IML] Quest: Brushmap as decal
On Sat, 15 Nov 1997, Richard Gowland wrote:
> I've been wanting to add a brushmap of some text to an object without the
> background overlaying the textures already on it. I've heard you can use a
> genlock feature in the brushmap but I don't know how to create it! If anyone
> knows how to do this with either paintshop pro or X-res I'll be eternally
> grateful.
You just need to make the background of the text a solid colour than
doesn't appear in the rest of the decal. Choose a colour close to your
object colour so the anti-aliased edges of the decal blend in.
Then apply the brushmap to your object and check the "use genlock" box on
the notebook page.
When you hit "render" and the dialog pops up, go to the last page and set
the genlock colour to whatever you chose. (It's the coloured box in the
bottom corner.)
Note: If you've got IFW 1.3.4, you've got IFF support.... IFF's can
store a genolck colour, but I don't know if either of your paint programs
will write them.
---------------------------------
Date: Tue, 16 Dec 1997 11:06:52 +0100
From: Torgeir Holm <torgeir@GIL.NO>
Subject: [IML] IFW: AADecal (was: Amiga: Transparent Brushmaps)
At 01:18 16/12/97 -0700, you wrote:
>Thanks to all the great replies. It was very simple and easily overlooked.
>Add the brush to the object and select USE GENLOCK. This sets color 0
>(0,0,0) to transparent.
Actually, when using index colored images color 0 can be any color. It's
just the first color in the palette.
One problem with the genlocking is that imagine interpolates the pixels in
the brushmap past the clipping. For example, if you have map with a red
circle on a black background, and you genlock this onto a white object, the
red circle will have a dark "halo" because it the red pixels are
interpolated towards black.
This is why I now use Mark Willis' AAdecal IFW texture for all this. It
lets you use Targa files with alpha channels, instead of the less than
perfect genlock clipping.
Check out the texture at the site below, they're well worth registering!!
http://www.mindspring.com/~maw01/aatxt/index.htm
---------------------------------
Date: Wed, 24 Sep 1997 22:05:09 +0400
From: Charles Blaquière <blaq@INTERLOG.COM>
Subject: Re: [IML] IFW: Genlock & Alpha Channel Problems
Roy Baker wrote:
>
> The problem is that the text has a black "outline" around it when I render
> the object. Im placing light colored text onto a light colored surface. The
> black outline is not acceptable for my work. Ive tried creating the text in
> several paint programs (being sure that "anti-aliasing" is turned off the
> text has jaggies and no blurring around the edges).
Roy,
first of all, welcome! I don't recall if the IML "welcome" message
mentions this, but you can search an archive of all past IML messages at
http://MAELSTROM.STJOHNS.EDU/CGI/wa.exe?S1=imagine
It's a great way to answer many questions, if you're worried about
posting a FAQ. Another great resource is Conny Joennsen Digestive IML, a
compendium of selected messages -- kind of a "IML greatest hits". The
URL:
http://MAELSTROM.STJOHNS.EDU/CGI/wa.exe?S1=imagine
Now, on to the topic at hand. Imagine's Genlock feature is strictly
on/off; on the other hand, Imagine anti-aliases all brushmaps. As a
result, the background bleeds into the bottom and left border pixels in
your text. (On the top and right sides, the Genlock kicks in _before_
anti-aliasing gets a chance to begin, so you don't see the border
effect) Having this outline appear on two adjoining sides does make it
look like a drop shadow; good observation.
The only way to avoid this is to bypass the Genlock feature entirely.
Instead, duplicate the object surface you're applying the brushmap to,
and move it off the object by a fraction of an Imagine unit. Then, make
a greyscale version of your text, in black over a white background, and
apply this to the floating surface, as a filter map. Imagine's Filter
attributes works like this: 0 = opaque, 255 = fully transparent. You can
see how your text will be opaque, while outside the text, the floating
surface will disappear.
You can now color the text by applying attributes and/or color
textures/brushmaps to the floating object. As a pleasant side effect,
you now have 256 levels of transparency, rather than the simple on/off
used by Genlock. This allows for transparency gradients or, better yet,
fully anti-aliased edges on your text! You can happily reactivate
anti-aliasing in your paint program.
A better way would be for Imagine to support 32-bit images with an
embedded alpha channel (this would remove the need to use a separate
floating object -- you could apply the 32-bit brushmap directly to the
original object), but for now this is the best you can do. By the way,
when Impulse mentioned "alpha channel support", I seem to recall they
meant as an output feature, to allow post-processing programs to
differentiate between objects and background in a finished Imagine
render. Supporting alpha channels in brushmaps may also have been talked
about, but I don't recall that.