How do you do this effects?

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Zamuel_a
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How do you do this effects?

Postby Zamuel_a » Thu Jan 24, 2013 9:32 pm

I have always been amazed by the effects done by the Overlanders in Froggies over the fence demo and wonder how they could do it. Effects like pixel precise dist in both x and y and the image that zooms and rotates or the 4 bitplanes zoom scrollers. I guess they must be using some clever tricks since a simple "plot pixel" routine wouldn't do it :wink:

The effects I was talking about starts at about 3:45 in the video

http://www.youtube.com/watch?v=HQ0VCg_K5UY
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troed
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Re: How do you do this effects?

Postby troed » Thu Jan 24, 2013 10:13 pm

Zamuel_a wrote:Effects like pixel precise dist in both x and y and the image that zooms and rotates or the 4 bitplanes zoom scrollers.


My immediate guess as to how the dists are done is precalculation of the permutations in a regular 8 pix wide (or 16, but I think they'd need too much mem) movep dist. Memory usage is halved if you only need it to be 2 pix wide instead of 1 etc.

The effects I was talking about starts at about 3:45 in the video


Trivia: You can link directly to a specific timestamp in a Youtube vid :) http://www.youtube.com/watch?v=HQ0VCg_K5UY&t=3m45s

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nativ
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Re: How do you do this effects?

Postby nativ » Fri Jan 25, 2013 12:04 am

I have some example code... in GFA.. it's either in the Spriteworks pack or I found it somewhere else.

it's easy I think using the blitter, you are applying some sine waves to the bitmap data.
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Zamuel_a
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Re: How do you do this effects?

Postby Zamuel_a » Fri Jan 25, 2013 6:14 am

This is a ST demo so they don't use any blitter :wink:
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