Building an Alpha-Shadow Animation

PNG/MNG Construction Set and the newly-updated animation plugins with alpha-channel support – the 3D Effects #1 plugin set, as of this writing – allow the creation of animations with sophisticated translucent shadows. Place such an animation over a textured surface or a photograph and its shadow will darken the details of its background, but not obscure them.
You’ll need PNG/MNG Construction Set 2.0a patch 77 or better to create these animations, and the 3D Effects #1 plugin set patch 17 or better.
Here’s how to create one:
- Open one of the 3D Effects #1 plugins from PNG/MNG Construction Set.
- Enable Alpha Transparency.
- Disable Alpha Background so you can choose the background color.
- Click on the Background button and set the background color to black. The background color will become the color of your shadow.
- Set up the other controls in the plugin to your liking and click on OK to build an animation.
- When the animation is complete and open in a PNG/MNG Construction Set document window, select Shadow from the Chunk menu.
- Configure the controls in the Shadow window to your liking. The Shadow Opacity control will adjust the density of your shadow – higher values will result in deeper shadows. Click on OK to complete the animation.
Your completed animation will show as having a black background in its PNG/MNG Construction Set document window, but it will display with a correct shadow if you click on View. By default, it will display against the current background color as defined by the Default Background Color button in PNG/MNG Construction Set’s Setup dialog. You can see it against another color by changing this, or by adding a BACK chunk to your animation.

At such time as you place this animation in a document – importing it into Animation Workshop or Presentation Wizard, for example – the background will become whatever it’s placed over. Note that not many non-Alchemy Mindworks applications support MNG animations with alpha-channel transparency.
If you’d like to create an animation like this for use on a web page – as we did for the example animations in this posting – you’ll need to reduce the true-color animation you’ve just built to a GIF file. This will remove its transparency – you won’t be able to place it over any background you like and have its shadow display flawlessly – but as long as you built it with a background to match that of your web page, it will look excellent.
Here’s how to reduce an alpha-shadow animation to a GIF file in PNG/MNG Construction Set.
- Add a BACK chunk to your alpha-shadow animation and set its color to the background you want for your animation. In the case of the animations for this page, it was set to white.
- Select Reconstruct from the Chunk menu of PNG/MNG Construction Set to render your alpha-shadow animation to a 24-bit animation with a solid background.
- Select Export to GIF from the File menu of PNG/MNG Construction Set to create a GIF animation.
Because the shadows in an alpha-shadow animation are generated as 32-bit objects, they look more convincing than the same shadows generated by the Shadow function in GIF Construction Set Professional.
You might want to see the general overview of alpha-channel animations at this blog as well.







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