Chessboard speed calc?

h0ffman · 13 September 2011, 01:21

I've been looking at chessboards lately. I get how they are done, quite a simple effect. However I'm wondering how you would you can calc the drawing so the zoom speed is constant?

The standard chessboard is drawn by increasing the pixel difference 1 dot at a time. I guess you wold still do that so you have a complete range but pick which line to use differently.

Basically I have and idea for a cooler chessboard but don't really want to give away too much of an idea as to what

Any help would be ace, cheers

Kalms · 13 September 2011, 02:16

First, what you describe is a bit off. The chessboard that you'll get is... well, you get larger squares toward you, but the maths is a bit off. But for the sake of argument, let's say that you like the shape of your chessboard.

Now remove the mask bitplane. Now you'll just have a gang of horizontal stripes, where the upper stripes are thin and they get thicker the further down on screen you get.

So you want to be able to scroll those stripes, slowly. With your current approach, it will be tricky. You will need to approach the problem from another angle.

Currently you have a formula which you use to "paint" lines, that is, "the next N lines should be white, and then <computes> the next N+1 lines should be black, etc". This generator function has worked well for your purposes so far, but now you're stuck.

You need to turn things on its head. You want a transformation where you provide only a Y coordinate, and the result back is either "white" or "black". Can you describe mathematically how to go - directly - from Y coordinate to color? Not using any lookup table? If you can use floating point maths?

If you find it too hard to do for stripes of increasing sizes, can you perhaps do it for stripes of equal sizes first?

And can you somehow make the black+white stripes change size over time, just by changing a scale factor inside of that transformation?

h0ffman · 13 September 2011, 19:35

Hmmm, i'm a little lost by your post if I'm honest, sorry.

I think what I'll do is a basic chessboard first.... then move from there, seeing as I haven't already done so.

h0ffman · 13 September 2011, 21:46

Right, well done the chess board... albeit a tad basic right now. All my own code too without reference

pmc · 14 September 2011, 08:31

Niiiiiice zoomer

StingRay's an expert on these zoomers I'd say, so he could give you some good tips, see here: http://www.pouet.net/prod.php?which=54138

done on a bootblock of course, just to underline that Stinger powah!

13 September 2011, 01:21	#1
h0ffman Registered User Join Date: Aug 2008 Location: Salisbury Posts: 744	Chessboard speed calc? I've been looking at chessboards lately. I get how they are done, quite a simple effect. However I'm wondering how you would you can calc the drawing so the zoom speed is constant? The standard chessboard is drawn by increasing the pixel difference 1 dot at a time. I guess you wold still do that so you have a complete range but pick which line to use differently. Basically I have and idea for a cooler chessboard but don't really want to give away too much of an idea as to what Any help would be ace, cheers

13 September 2011, 02:16	#2
Kalms Registered User Join Date: Nov 2006 Location: Stockholm, Sweden Posts: 237	First, what you describe is a bit off. The chessboard that you'll get is... well, you get larger squares toward you, but the maths is a bit off. But for the sake of argument, let's say that you like the shape of your chessboard. Now remove the mask bitplane. Now you'll just have a gang of horizontal stripes, where the upper stripes are thin and they get thicker the further down on screen you get. So you want to be able to scroll those stripes, slowly. With your current approach, it will be tricky. You will need to approach the problem from another angle. Currently you have a formula which you use to "paint" lines, that is, "the next N lines should be white, and then <computes> the next N+1 lines should be black, etc". This generator function has worked well for your purposes so far, but now you're stuck. You need to turn things on its head. You want a transformation where you provide only a Y coordinate, and the result back is either "white" or "black". Can you describe mathematically how to go - directly - from Y coordinate to color? Not using any lookup table? If you can use floating point maths? If you find it too hard to do for stripes of increasing sizes, can you perhaps do it for stripes of equal sizes first? And can you somehow make the black+white stripes change size over time, just by changing a scale factor inside of that transformation? Last edited by Kalms; 13 September 2011 at 02:44. Reason: same principle, but let's take it in a slightly different direction

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13 September 2011, 19:35	#3
h0ffman Registered User Join Date: Aug 2008 Location: Salisbury Posts: 744	Hmmm, i'm a little lost by your post if I'm honest, sorry. I think what I'll do is a basic chessboard first.... then move from there, seeing as I haven't already done so.

14 September 2011, 08:31	#5
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	Niiiiiice zoomer StingRay's an expert on these zoomers I'd say, so he could give you some good tips, see here: http://www.pouet.net/prod.php?which=54138 done on a bootblock of course, just to underline that Stinger powah!

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