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using Manic Miner and Jet Set Willy game engines
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Message: 6995
Author: rushforthian
Date: 27/12/2016
Subject: Re: Mirror MM/JSW / MM - JSW Conversions
One final thought - where there are horizontal AND vertical guardian instances in a game which utilise the same set of sprites (e.g the Rolling Atlases in original JSW, which is a horizontal guardian in 'The Bathroom' and 'To the Kitchens / Main Stairway', but there is an instance of one that moves vertically in 'On a Branch over the Drive'), then it isn't possible to get absolute lateral inversion AND get the timing of the start-frame correct in both cases.
That's because laterally-inverting a four-frame, unidirectional horizontal guardian involves swapping the position of the sprite-frames around, as well as horizontally reflecting their pixel-patterns. Whereas laterally-inverting a vertical guardian only involves the latter process.
So in order to faithfully replicate perfectly-timed lateral inversions of both, you would have to use a separate half-page of guardian sprite-frames (copying them over from the originals, but with the order inverted).
Having said that, in the original game the vertical instance of the Rolling Atlases isn't very elegant in the way it is animated anyway. So if you have space in the code to replicate the existing four sprite-frames, you might as well 'fix' the jerky animation by giving its vertical incarnation eight sprites (thereby allowing it to go either 'round and round', or 'side-to-side', in a much smoother manner).
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