90 lines
6.9 KiB
Groff
90 lines
6.9 KiB
Groff
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|For those of you who don't know how the SNES does do it's graphics, it |
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|uses tiles (surprise surprise!). |
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|There are different MODEs on the SNES; the most famous being MODE 7. |
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|Most people think that $2106 (Screen Pixelation: Look in SNES.1 for an ex- |
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|planation on this register) is MODE 7. *** THIS IS NOT MODE 7!!! ***. |
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|So, the next time the pixels get really "big" (almost making them look like |
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|look like IBM-clone 320x200x256 MODE 13h graphics), and your friend says |
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|"WOW! MODE 7 is really awesome," punch him/her in the nose for me. Just |
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|joking. :-) |
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|I'll be explaining MODE 1. I know how MODE 7 works, but since i've never |
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|used it, don't plan on me explaining it in the near future. Sorry to those |
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|who were looking for a MODE 7 document. Look elsewhere... |
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|MODE # of BGs MaxColour/Tile Palettes Colours |
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|0 4 4 8 32 |
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|1 3 16/16/4 8 128 |
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|MODE 0 is good for geometric shapes (if you were going to rotate a wire- |
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|frame cube, or something like that), basic star scrolls, or a very 'bland' |
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|text scroller... it's pretty cool and doesn't take up much space. |
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|I'm going to explain MODE 1, since MODE 0 is the same thing but with less |
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|bitplanes. :-) |
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|MODE 1 is really best for things; detailed star scrolls, text scrollers, |
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|geometric shapes, and filled objects. It's the most common used MODE in the |
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|the professional SNES programming world. |
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|You need to "setup the plane" to tell it what tile goes where. If you want |
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|demo-code, check out 'test.asm' in 'test.lzh'. |
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|----------------------------------------------------------------------------|
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|So, lets assume we have a character (a 8x8 tile) which we want to work with |
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|to figure out the SNES's colour scheme: |
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|TestCHR1 dcb $00,$00,$00,$00,$00,$00,$00,$00 ; '@' |
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|TestCHR2 dcb $00,$3C,$4E,$5E,$5E,$40,$3C,$00 ; '@' |
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|You're probably wondering how the two lines above turn into actual graphic |
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|data on your monitor or television set. Very simple. Consider each byte |
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|(each new $xx statement) a new pixel line. Tile size is 8x8. |
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| %00000000 = $00 |
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| %00000000 = $00 This is TestCHR1 |
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| %00000000 = $00 |
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| %00000000 = $00 |
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| %00000000 = $00 |
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| %00000000 = $00 |
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| %00000000 = $00 |
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| %00000000 = $00 |
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| |
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| %00000000 = $00 |
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| %00111100 = $3C This is TestCHR2 |
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| %01001110 = $4E |
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| %01011110 = $5E |
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| %01011110 = $5E |
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| %01000000 = $40 |
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| %00111100 = $3C |
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| %00000000 = $00 |
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|The at-symbol ('@') is visible in TestCHR2. Now you're probably wondering |
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|"Well, that tells me how to define a pixel on and off; what about the colour|
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|itself!" Once again, very simple, but a tad more complex: |
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|If you have a 0 for bitplane 0, a 0 for bitplane 1, a 0 for bitplane 2, |
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|and a 0 for bitplane 3, you get color #0; eg.: |
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| 0000 = Color #0 |
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| ||||___________Bitplane 0 |
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| |||__________Bitplane 1 |
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| ||_________Bitplane 2 |
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| |________Bitplane 3 |
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|So, now, think about a 0 for bitplane 0, a 1 for bitplane 1 and 2, and a 0 |
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|for bitplane 3: |
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| 0110 = Color #6 |
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| ||||___________Bitplane 0 |
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| |||__________Bitplane 1 |
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| |_________Bitplane 2 |
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| |________Bitplane 3 |
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|Keep in mind, this is the best explanation i've ever seen done about SNES |
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|pixel color definition. Until I see better, I'd have to say this is the |
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|best it's gonna get. |
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|The result above gives you the color # per pixel; it's interesting. It's an |
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|"overlay" method, so-to-speak, not to confuse this w/ main and sub-screens. |
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