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Krill
Registered: Apr 2002
Posts: 2855 |
Bobby Border
One of the most impressive pieces of code (and design!) on this platform is still Glasnost 's part in Camel Park - the one from the screenshot, particularly the side-border DXYCP scroller.
Now, i've never really gotten around to analyse it thoroughly.
And being lazy... How? :) |
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Krill
Registered: Apr 2002
Posts: 2855 |
Anyways, what i'm wondering about is how the scroller seems so... variable in Y-positioning the characters, while there are obviously very tight restrictions regarding multiplexing, especially with open sideborders.
My guess is that the entire movement and positioning was precalculated, and then some kind of best-fit algorithm (maybe with some manual tweaking) squeezed all individual frames into the corset of hardware limitations.
(There seem to be some artefacts regarding the positioning.) |
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HCL
Registered: Feb 2003
Posts: 717 |
@Krill: I think you know all the tech that is behind that part(s). It's just executed to perfection. Sprites are on constant y-position and only moves in x-direction. Since it's moving rather quickly, i assume a few 256-byte tables for d010 are sufficient. Then the d011-stretcher effect in the background, you know how to do it.. but it has to be rather table-driven in order to not waste rastertime outside the timing, and the timing for it sort of comes for free.. |
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Krill
Registered: Apr 2002
Posts: 2855 |
The raster tricks themselves are not the question to me, indeed. :)
(I'm that guy who likes to respond to the old "Sprites or chars?" question with "Yes.") |
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Oswald
Registered: Apr 2002
Posts: 5031 |
fix Y coordinate of the virtual bobs explains what you wanted to know I guess. |
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Oswald
Registered: Apr 2002
Posts: 5031 |
framestepping it at YT, it seems like it is rather fixed in X, that makes the Xcoo "changes" easy :) so its basicly an only Y mover bob routine plotted into sprites with fixed X coo baked into sprite x changes. |
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Krill
Registered: Apr 2002
Posts: 2855 |
Quoting Oswaldfix Y coordinate of the virtual bobs explains what you wanted to know I guess. That much is obvious from just looking at it. What do you mean by "virtual"? |
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Oswald
Registered: Apr 2002
Posts: 5031 |
Quote: Quoting Oswaldfix Y coordinate of the virtual bobs explains what you wanted to know I guess. That much is obvious from just looking at it. What do you mean by "virtual"?
so what you wanted to know then, when you know how everything works?
individual sprites are teared up into virtual sprites with the xcoo changes. |
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Krill
Registered: Apr 2002
Posts: 2855 |
Quoting Oswaldso what you wanted to know then, when you know how everything works?
individual sprites are teared up into virtual sprites with the xcoo changes. More high-level: If/how the virtual character positions are mapped to the available slots.
"My guess is that the entire movement and positioning was precalculated, and then some kind of best-fit algorithm (maybe with some manual tweaking) squeezed all individual frames into the corset of hardware limitations.
(There seem to be some artefacts regarding the positioning.)" |
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Oswald
Registered: Apr 2002
Posts: 5031 |
yeah the positional "bugs" with the scroller its somehow more visible. anyway you just sit down and use some high level language to try out sinuses, find best fit, fix those few issue remaining by hand I guess. |
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Krill
Registered: Apr 2002
Posts: 2855 |
Quoting Oswaldanyway you just sit down and use some high level language to try out sinuses, find best fit, fix those few issue remaining by hand I guess. Wonder how that looked like in 1994. |
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