How did Super Mario Bros. 3 create this tunnel vision effect?
In a certain section of World 8's map, the screen is black except for a small circle surrounding Mario (as seen below during this speedrun).
After doing a little research, I discovered that the game's cartridge contains a special mapper chip. This mapper, labeled MMC3, allows the generation of raster interrupts which are normally unavailable on the NES. In other words, the CPU can be interrupted, at most, once per scanline. Code may then be placed inside this interrupt to adjust certain PPU registers on a per-scanline basis, allowing for visual effects such as (presumably) the tunnel vision effect seen above.
What I don't understand, however, is how this specific effect was achieved (i.e., exactly what PPU registers the raster interrupts modified, if raster interrupts were even used at all).
nintendo nes
asked yesterday
cschultz2048
25325
add a comment |
In a certain section of World 8's map, the screen is black except for a small circle surrounding Mario (as seen below during this speedrun).
After doing a little research, I discovered that the game's cartridge contains a special mapper chip. This mapper, labeled MMC3, allows the generation of raster interrupts which are normally unavailable on the NES. In other words, the CPU can be interrupted, at most, once per scanline. Code may then be placed inside this interrupt to adjust certain PPU registers on a per-scanline basis, allowing for visual effects such as (presumably) the tunnel vision effect seen above.
What I don't understand, however, is how this specific effect was achieved (i.e., exactly what PPU registers the raster interrupts modified, if raster interrupts were even used at all).
nintendo nes
asked yesterday
cschultz2048
25325
add a comment |
In a certain section of World 8's map, the screen is black except for a small circle surrounding Mario (as seen below during this speedrun).
After doing a little research, I discovered that the game's cartridge contains a special mapper chip. This mapper, labeled MMC3, allows the generation of raster interrupts which are normally unavailable on the NES. In other words, the CPU can be interrupted, at most, once per scanline. Code may then be placed inside this interrupt to adjust certain PPU registers on a per-scanline basis, allowing for visual effects such as (presumably) the tunnel vision effect seen above.
What I don't understand, however, is how this specific effect was achieved (i.e., exactly what PPU registers the raster interrupts modified, if raster interrupts were even used at all).
nintendo nes
asked yesterday
cschultz2048
25325
In a certain section of World 8's map, the screen is black except for a small circle surrounding Mario (as seen below during this speedrun).
After doing a little research, I discovered that the game's cartridge contains a special mapper chip. This mapper, labeled MMC3, allows the generation of raster interrupts which are normally unavailable on the NES. In other words, the CPU can be interrupted, at most, once per scanline. Code may then be placed inside this interrupt to adjust certain PPU registers on a per-scanline basis, allowing for visual effects such as (presumably) the tunnel vision effect seen above.
What I don't understand, however, is how this specific effect was achieved (i.e., exactly what PPU registers the raster interrupts modified, if raster interrupts were even used at all).
nintendo nes
nintendo nes
asked yesterday
cschultz2048
25325
asked yesterday
cschultz2048
25325
asked yesterday
cschultz2048
25325
asked yesterday
cschultz2048
25325
asked yesterday
cschultz2048
25325
25325
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
No MMC3 tricks are used for this effect; just standard background and sprite manipulation. Tiles that are completely invisible are replaced with a blank tile, while black sprites forming a circle outline cover the partially-visible tiles.
We can make the effect more obvious by drawing background and sprites separately (and coloring the circle sprites white instead of black):
answered yesterday
NobodyNada
3,0411428
4
+1 excellent GIF. I was beginning to suspect that this was the case, but I appreciate you confirming my suspicions.
– cschultz2048
yesterday
add a comment |
I can't comment, but here's a link to the "source code" to Super Mario Bros. 3, with comments. https://github.com/captainsouthbird/smb3
answered 4 hours ago
C. Uwakweh
1
New contributor
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'm surprised this is even legal
– ChatterOne
3 hours ago
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
No MMC3 tricks are used for this effect; just standard background and sprite manipulation. Tiles that are completely invisible are replaced with a blank tile, while black sprites forming a circle outline cover the partially-visible tiles.
We can make the effect more obvious by drawing background and sprites separately (and coloring the circle sprites white instead of black):
answered yesterday
NobodyNada
3,0411428
4
+1 excellent GIF. I was beginning to suspect that this was the case, but I appreciate you confirming my suspicions.
– cschultz2048
yesterday
add a comment |
No MMC3 tricks are used for this effect; just standard background and sprite manipulation. Tiles that are completely invisible are replaced with a blank tile, while black sprites forming a circle outline cover the partially-visible tiles.
We can make the effect more obvious by drawing background and sprites separately (and coloring the circle sprites white instead of black):
answered yesterday
NobodyNada
3,0411428
4
+1 excellent GIF. I was beginning to suspect that this was the case, but I appreciate you confirming my suspicions.
– cschultz2048
yesterday
add a comment |
No MMC3 tricks are used for this effect; just standard background and sprite manipulation. Tiles that are completely invisible are replaced with a blank tile, while black sprites forming a circle outline cover the partially-visible tiles.
We can make the effect more obvious by drawing background and sprites separately (and coloring the circle sprites white instead of black):
answered yesterday
NobodyNada
3,0411428
No MMC3 tricks are used for this effect; just standard background and sprite manipulation. Tiles that are completely invisible are replaced with a blank tile, while black sprites forming a circle outline cover the partially-visible tiles.
We can make the effect more obvious by drawing background and sprites separately (and coloring the circle sprites white instead of black):
answered yesterday
NobodyNada
3,0411428
answered yesterday
NobodyNada
3,0411428
answered yesterday
NobodyNada
3,0411428
answered yesterday
NobodyNada
3,0411428
3,0411428
4
+1 excellent GIF. I was beginning to suspect that this was the case, but I appreciate you confirming my suspicions.
– cschultz2048
yesterday
add a comment |
4
+1 excellent GIF. I was beginning to suspect that this was the case, but I appreciate you confirming my suspicions.
– cschultz2048
yesterday
4
4
+1 excellent GIF. I was beginning to suspect that this was the case, but I appreciate you confirming my suspicions.
– cschultz2048
yesterday
+1 excellent GIF. I was beginning to suspect that this was the case, but I appreciate you confirming my suspicions.
– cschultz2048
yesterday
add a comment |
I can't comment, but here's a link to the "source code" to Super Mario Bros. 3, with comments. https://github.com/captainsouthbird/smb3
answered 4 hours ago
C. Uwakweh
1
New contributor
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'm surprised this is even legal
– ChatterOne
3 hours ago
add a comment |
I can't comment, but here's a link to the "source code" to Super Mario Bros. 3, with comments. https://github.com/captainsouthbird/smb3
answered 4 hours ago
C. Uwakweh
1
New contributor
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'm surprised this is even legal
– ChatterOne
3 hours ago
add a comment |
I can't comment, but here's a link to the "source code" to Super Mario Bros. 3, with comments. https://github.com/captainsouthbird/smb3
answered 4 hours ago
C. Uwakweh
1
New contributor
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I can't comment, but here's a link to the "source code" to Super Mario Bros. 3, with comments. https://github.com/captainsouthbird/smb3
answered 4 hours ago
C. Uwakweh
1
New contributor
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 4 hours ago
C. Uwakweh
1
New contributor
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 4 hours ago
C. Uwakweh
1
answered 4 hours ago
C. Uwakweh
1
1
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C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
C. Uwakweh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'm surprised this is even legal
– ChatterOne
3 hours ago
add a comment |
I'm surprised this is even legal
– ChatterOne
3 hours ago
I'm surprised this is even legal
– ChatterOne
3 hours ago
I'm surprised this is even legal
– ChatterOne
3 hours ago
add a comment |
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