Hello,
I'm confused on the very principle of what's meant by "scanlines." I think part of my problem is I come from a video background rather than a computer science background, so when I read "scanline" I've been envisioning something similar to a "scan line" on a CRT screen. In other words, for the NES I'm envisioning a horizontal scanline being a line of pixels 1 pixel high by 256 pixels wide, and there would be 240 of these sequentially layered top to bottom of the screen.
However, the more I read the more I'm starting to think it's something a bit different. Mostly, it's the "8 sprites per scanline at one time" rule that's really throwing me. I understand that each sprite is 8x8 pixels (or, rarely, might be 8x16). But as I look at screenshots of various NES games, it seems there are way more than 8 different sprites on the same line, even counting the many that get repeated.
Again, my first conclusion is that I do not properly understand what a scanline is taken in the context of the NES display output. But if I do, could someone please tell me what I'm missing with the "8 sprites per scanline rule"? Perhaps there's some trick I'm not aware of? Or perhaps extra hardware on the cartridges allows there to be more? Perhaps I'm not looking at the my these screenshots correctly?
I'm reading Patrick Deskin's NES System Doc and these forums and just barely getting my feel wet (as everyone can tell). I haven't found a thread discussing a basic definition of scanlines yet but if there is one 1. I apologize and 2. please point me to it.
And thanks folks for what you do on this site. It's all really fascinating.
I'm confused on the very principle of what's meant by "scanlines." I think part of my problem is I come from a video background rather than a computer science background, so when I read "scanline" I've been envisioning something similar to a "scan line" on a CRT screen. In other words, for the NES I'm envisioning a horizontal scanline being a line of pixels 1 pixel high by 256 pixels wide, and there would be 240 of these sequentially layered top to bottom of the screen.
However, the more I read the more I'm starting to think it's something a bit different. Mostly, it's the "8 sprites per scanline at one time" rule that's really throwing me. I understand that each sprite is 8x8 pixels (or, rarely, might be 8x16). But as I look at screenshots of various NES games, it seems there are way more than 8 different sprites on the same line, even counting the many that get repeated.
Again, my first conclusion is that I do not properly understand what a scanline is taken in the context of the NES display output. But if I do, could someone please tell me what I'm missing with the "8 sprites per scanline rule"? Perhaps there's some trick I'm not aware of? Or perhaps extra hardware on the cartridges allows there to be more? Perhaps I'm not looking at the my these screenshots correctly?
I'm reading Patrick Deskin's NES System Doc and these forums and just barely getting my feel wet (as everyone can tell). I haven't found a thread discussing a basic definition of scanlines yet but if there is one 1. I apologize and 2. please point me to it.
And thanks folks for what you do on this site. It's all really fascinating.