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PostPosted: Mon Jan 23, 2006 10:40 pm 
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Another advantage to 2x2 meta tiles is that collision detection is SO much easier, since there aren't more than $FF meta tiles on screen at once. You can read the bytes of maps easier, you can just read map,x to read any tile on the screen, due to there only being $FF tiles. This is why making my NES meta tile layer was so easy to do.


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PostPosted: Mon Jan 23, 2006 10:49 pm 
The NTSC C64 has 262 lines, with 200 of them being addressable screen.


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PostPosted: Tue Jan 24, 2006 9:57 am 
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Celius wrote:
Another advantage to 2x2 meta tiles is that collision detection is SO much easier, since there aren't more than $FF meta tiles on screen at once. You can read the bytes of maps easier, you can just read map,x to read any tile on the screen, due to there only being $FF tiles. This is why making my NES meta tile layer was so easy to do.

What you say here is a nonsense. Having 2x2 or 4x4 collision detection changes strictly nothing to how easy or hard collision detection is. And how much metatiles on screen at once there is, your engine determine it totally independantly of the meatile size. I've done collision detection without trouble with my block system I descibed above.

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PostPosted: Tue Jan 24, 2006 10:09 am 
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LocalH wrote:
The NTSC C64 has 262 lines, with 200 of them being addressable screen.

These lines consist of roughly 20 lines of border, 200 lines of picture, 20 lines of border, and 22 lines of vblank. Some hardware producers don't like a lot of border.


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PostPosted: Tue Jan 24, 2006 4:23 pm 
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Bregalad wrote:
What you say here is a nonsense. Having 2x2 or 4x4 collision detection changes strictly nothing to how easy or hard collision detection is. And how much metatiles on screen at once there is, your engine determine it totally independantly of the meatile size. I've done collision detection without trouble with my block system I descibed above.


I disagree. When doing collision detection with a 32x30 map, it really complicates things, because you have to deal with changing the high byte of the map address. You usually load bytes with indirect indexed addressing, and you have to do many routines with comparing Y positions, and changing high bytes. Okay, it's a little hard to explain, but my collision detection code for 32x30 was WAY longer and WAY more complicated than my 16x15 map. You don't have to use indirect indexed addressing for such a thing. Well, you probably should to be a little more relative with the routines, but you could just say map,x to load any byte of the map, where as you cannot with 32x30 maps, because there are more than $FF bytes.


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PostPosted: Tue Jan 24, 2006 6:26 pm 
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Celius is right by saying it is easier to work with the maps if you can access the whole screen by modifying only the index register and not the base address.

But then again, any block size from 16x16 up will grant you that possibility, and not many games will work at the tile-level, as it wastes a lot of space. I think only really old, static screen kind of games used tile-level maps. Anything newer than that will most likely use 16x16 or more.


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PostPosted: Tue Jan 24, 2006 7:33 pm 
tepples wrote:
LocalH wrote:
The NTSC C64 has 262 lines, with 200 of them being addressable screen.

These lines consist of roughly 20 lines of border, 200 lines of picture, 20 lines of border, and 22 lines of vblank. Some hardware producers don't like a lot of border.

On the other hand, the C64 has a huge horizontal border - quite a few more pixels per line outside of blanking as compared to something like the Genesis. Also, the 262 line C64's are only the earlier ones with 64 cycles per line - the newer 65-cycle NTSC VIC-IIs have 263 lines. And, for completeness, the PAL C64 has 63 cycles per line and 312 lines.


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PostPosted: Wed Jan 25, 2006 10:57 am 
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Celius wrote:
I disagree. When doing collision detection with a 32x30 map, it really complicates things, because you have to deal with changing the high byte of the map address. You usually load bytes with indirect indexed addressing, and you have to do many routines with comparing Y positions, and changing high bytes. Okay, it's a little hard to explain, but my collision detection code for 32x30 was WAY longer and WAY more complicated than my 16x15 map. You don't have to use indirect indexed addressing for such a thing. Well, you probably should to be a little more relative with the routines, but you could just say map,x to load any byte of the map, where as you cannot with 32x30 maps, because there are more than $FF bytes.

So that means that having 8x8 metatiles is harder than having 16x16 metatiles, wich I agree with you. However, 16x16 metatiles aren't in any way easier or harder than 32x32 metatiles at this level, they're just different.
In an advanced RPG, you'll want to have large scrolling maps, so even with 16x16 metatiles, the larger maps will easily get larger than 256 bytes once decompressed. It sure is a bit more odd to handle, but no programmer should flee against difficulty anyway.

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