Dark Bit Factory & Gravity
PROGRAMMING => General coding questions => Topic started by: spathi on August 31, 2014
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Wondering how "spiral copper" effects are done, where it will appear that several copper bars are twining together in a double or triple helix. There are also a lot of other effects that use this, like square columns that seem to be twisting and untwisting, that sort of thing.
Here is an example of a crazy effect using this, starts at 14:50 or so:
https://www.youtube.com/watch?v=pssH6moTGLc
Obviously the individual columns of a bitmap are being shifted based on a sine wave to get the cylindrical effect, but how exactly?
Perhaps I am being foolish and it isn't really being mapped onto a cylinder...
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That's a pretty cool effect, and a neat demo thanks for posting the link.
I agree its probably a sine distortion in the y direction of some kind but I'm terrible at this kind of mapping stuff. Moving pixel rows up and down out of phase and using positive/negative values to determine if its the front or the back and then adding some white or dark highlights near the 0 values of the sine.
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It could very well just be a non-perspective horizontal shift. Perhaps the shifting produces a forced perspective effect.