Honestly, I was already impressed by the work you are showing about the book, and I enjoyed reading through MD Shock, but this is the first time I’ve taken the time and I’ve really understood how the MD graphics worked. I suppose most of this info already existed on the internet, but this is an awesome newcomer BUT detailed guide. IMO that’s hard to make, as you cannot be 100% technical but you cannot be 100% theorical, and I really think you have nailed it. There are so many concepts I’ve read about on emulation but didn’t fully understand until now…
I’ll forever be grateful for letting me understand my favourite console from youth. Keep doing what you are doing, because it’s hard to find this kind of content. Really thanks and good luck finishing the book!! Really looking forward to reading it!!
It’s good to hear that some sense can be made of all of this! I think a lot of what it takes to understand the hardware is to just see as many examples as possible. I hope to add more examples as time goes, but I’m thankful to all the people online who are already sharing these examples because it takes a lot of effort to spot the more subtle ones.
And I’m glad to hear you’re excited about the book. It’s really a dream come true to be able to write it.
Yes, both shadow and highlight can be applied at the same time to different parts of the screen. There is only one mode for shadow/highlight, and when it is enabled, both can be used. If we’re using sprites to do it, then any sprite pixel that is set to color 15 of palette 3 will shadow the planes under it, and any sprite pixel that is set to color 14 of palette 3 will highlight the planes under it. These can be used simultaneously.
Off the top of my head, I don’t know of any good examples of games that used both at the same time, though.
Thanks for the answer, Jharrison! Your website is incredible and very informative, I hope you continue with the posts.
It is interesting how powerful this technique is, but unfortunately, few games have taken advantage of it.
I’ll try to make an effort to buy the book, but as our currency started to devalue (Real – Brazilian), everything that is bought in dollar is very expensive for us. 🙁
I’ve had a question about S/H since Lucas commented. In Ranger X, are planes A and B low priority, while Shadow is high priority? Or is Plane B the only one with low priority? I ask this because I learned how to use S/H mode in some games that have similar engines to Sonic games, and it’s possible to activate S/H by changing some bytes via emulator. But look what happened, it looks like the plane A tiles break the shadow, even if the tiles are empty. https://imgur.com/gallery/ovVbF46
Can’t plan A have a higher priority than the shadow activated between the planes without these breaks occurring close to the tiles, even if they are empty tiles?
It sounds like you’re talking about plane-based shadowing, so let’s ignore sprite-based shadowing/highlighting for now.
For plane-based shadowing to appear on a particular tile, two things must be true: 1) S/H mode must obviously be enabled, and 2) BOTH Plane A and Plane B must be low priority at that tile location. Once those conditions are met, then the tile will become shadowed. There is no Shadow plane or anything like that (so it’s never the case that ‘Shadow is high priority’).
In the Ranger-X cave stage, both Plane A and Plane B are low priority throughout the stage (so the entire stage is shadowed). When the player shoots the ceiling to let in the light, then one plane becomes high priority, which cancels the shadow effect at that location.
In the case where you enable S/H mode in an emulator, you’ll only see shadow where both planes are low priority. If one plane (A or B) is high priority, even if it is transparent, then shadow will not be applied. For your Dynamite Headdy example, the foreground tiles in question have high priority, so they are not shadowed (even when they are transparent). It might be possible to reduce the high-priority transparent borders around the foreground objects a bit more, but I don’t know specifically.
There’s no way to have foreground tiles at high priority and still use shadow at that tile position. This is one of the disadvantages of S/H mode– you can’t have the player pass behind a shadowed foreground object, for example.
Nice site! Your references are great and line up with a lot of mine, here are some more:
https://www.eecg.utoronto.ca/~moshovos/ECE243-07/?fbclid=IwAR0ah923TBXVkuHV825utexa2JCMslG665ydJmI8HB9QTp8MX0Bvfvepsgo
https://www.chibiakumas.com/68000/#Lesson1
I’m trying to learn and wish to work with the Genesis in the near future.
Thanks, Kent! Those look like great references.
Best of luck in working with the Genesis!
Honestly, I was already impressed by the work you are showing about the book, and I enjoyed reading through MD Shock, but this is the first time I’ve taken the time and I’ve really understood how the MD graphics worked. I suppose most of this info already existed on the internet, but this is an awesome newcomer BUT detailed guide. IMO that’s hard to make, as you cannot be 100% technical but you cannot be 100% theorical, and I really think you have nailed it. There are so many concepts I’ve read about on emulation but didn’t fully understand until now…
I’ll forever be grateful for letting me understand my favourite console from youth. Keep doing what you are doing, because it’s hard to find this kind of content. Really thanks and good luck finishing the book!! Really looking forward to reading it!!
It’s good to hear that some sense can be made of all of this! I think a lot of what it takes to understand the hardware is to just see as many examples as possible. I hope to add more examples as time goes, but I’m thankful to all the people online who are already sharing these examples because it takes a lot of effort to spot the more subtle ones.
And I’m glad to hear you’re excited about the book. It’s really a dream come true to be able to write it.
You’ve done so-o huge and intresting work here. Thanks!
Hi!
Can the shadow and the highlight be applied to specific parts of the screen at the same time? Or while I use one, can’t I use the other one?
Lucas,
Yes, both shadow and highlight can be applied at the same time to different parts of the screen. There is only one mode for shadow/highlight, and when it is enabled, both can be used. If we’re using sprites to do it, then any sprite pixel that is set to color 15 of palette 3 will shadow the planes under it, and any sprite pixel that is set to color 14 of palette 3 will highlight the planes under it. These can be used simultaneously.
Off the top of my head, I don’t know of any good examples of games that used both at the same time, though.
Thanks for the answer, Jharrison! Your website is incredible and very informative, I hope you continue with the posts.
It is interesting how powerful this technique is, but unfortunately, few games have taken advantage of it.
I’ll try to make an effort to buy the book, but as our currency started to devalue (Real – Brazilian), everything that is bought in dollar is very expensive for us. 🙁
Hello guys, great article, I liked it a lot!
I’ve had a question about S/H since Lucas commented. In Ranger X, are planes A and B low priority, while Shadow is high priority? Or is Plane B the only one with low priority?
I ask this because I learned how to use S/H mode in some games that have similar engines to Sonic games, and it’s possible to activate S/H by changing some bytes via emulator. But look what happened, it looks like the plane A tiles break the shadow, even if the tiles are empty.
https://imgur.com/gallery/ovVbF46
Can’t plan A have a higher priority than the shadow activated between the planes without these breaks occurring close to the tiles, even if they are empty tiles?
Thanks for listening!
Hi Hamilton,
It sounds like you’re talking about plane-based shadowing, so let’s ignore sprite-based shadowing/highlighting for now.
For plane-based shadowing to appear on a particular tile, two things must be true: 1) S/H mode must obviously be enabled, and 2) BOTH Plane A and Plane B must be low priority at that tile location. Once those conditions are met, then the tile will become shadowed. There is no Shadow plane or anything like that (so it’s never the case that ‘Shadow is high priority’).
In the Ranger-X cave stage, both Plane A and Plane B are low priority throughout the stage (so the entire stage is shadowed). When the player shoots the ceiling to let in the light, then one plane becomes high priority, which cancels the shadow effect at that location.
In the case where you enable S/H mode in an emulator, you’ll only see shadow where both planes are low priority. If one plane (A or B) is high priority, even if it is transparent, then shadow will not be applied. For your Dynamite Headdy example, the foreground tiles in question have high priority, so they are not shadowed (even when they are transparent). It might be possible to reduce the high-priority transparent borders around the foreground objects a bit more, but I don’t know specifically.
There’s no way to have foreground tiles at high priority and still use shadow at that tile position. This is one of the disadvantages of S/H mode– you can’t have the player pass behind a shadowed foreground object, for example.
Hope that helps!