POV-Ray : Newsgroups : povray.binaries.images : Using "transmit all" with an image map : Re: Using "transmit all" with an image map Server Time
17 Apr 2024 18:31:51 EDT (-0400)
  Re: Using "transmit all" with an image map  
From: Dave Blandston
Date: 30 Dec 2022 22:05:00
Message: <web.63afa698eaa53b9ca65171949334df62@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> This seems to be very weird behaviour.  Have you checked somehow to see that the
> alpha channel isn't as fully transparent as you think or is corrupted in some
> way?
> A graphics editor with an eyedropper tool usually displays the rgbt values.
> Not sure if this well help, and it's a hacky workaround, but maybe you can use
> different image mapped shapes - like a cylinder or disc for the ABBA image?  Or
> use intersection or difference?  Just a thought.
> Also make sure your scene is set up correctly.   Not sure about that background
> statement.   I'd kill that and put up a plane or other object, just to see if
> there isn't some strange under-the-hood thing going on with those
> angle-independent keywords.
> Good luck,
> BE

Placing an object in the background doesn't change anything unfortunately. The
problem first appeared with a box {} as a background.

I hadn't thought of the possibility that the image editing program I'm using
(Paint.net) might be doing something weird with the alpha channel so I made a
test image with Photoshop and it didn't work either.

The ABBA image is just a random image for demonstration. The goal is to be able
to supply an image of a website element (button, logo, et cetera) and make it
fade in and out during an animation sequence. It's working great except for
images with transparent portions. It gets even weirder sometimes - I tried the
following layers, from back to front: A totally opaque box (the frame of a
video), an image with opaque areas and transparent areas (animated text), a
white box that was fading from opaque to transparent with "transmit all" to
reveal the objects behind it, a box with opaque and transparent areas (video
player controls), a box with a transparent window for the video to show through,
then another box with a transparent window that represents a web browser frame.
Out of all these objects, I don't think there was one certain one that wrecked
the scene but a combination, since other combinations do work. But this
particular combination resulted in very odd transparency areas. I think there's
just something strange going on with how POV-Ray handles .png alpha channels.

I'll attach a sample image using most of the items in the list above (everything
except the fading white box, which I removed) so maybe it will make more sense.

Have a great day!

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