4 ms·

Author here, happy to answer any questions you might have.

by jix 9y ago

tawayway 9y ago
Congrats (and thanks) for the amazing prod :)
w0utert 9y ago
Absolutely awesome demo, thanks for the writeup of this impressive feat!
sergior 9y ago
I am trying to find my jaw. Haha no questions. Amazing stuff!
faragon 9y ago
Choosing 50 FPS instead of 60 was because needing to dedicate more CPU to each frame, or because another reason? P.S. Impressive demo, kudos :-)
- shinymark 9y ago
  PAL vs NTSC perhaps?
- jix 9y ago
  For the Mega Drive/Genesis the framerate depends on the region, matching the local video standard. The European Mega Drive uses PAL with 50Hz. As the biggest part (but not all) of the demoscene is based in Europe, most demos target PAL hardware. The same is true for our demo group. NTSC ports can be very difficult if not impossible as PAL often does have a slight advantage in CPU cycles per frame. This is also the case on the Mega Drive. Porting the polygon renderer shouldn't be a problem as it renders in an off-screen CPU RAM buffer. In the worst case it would have to skip more frames, having a lower effective framerate. A lot of the other effects have very critical timing though. I've been told that porting some of them to NTSC is just impossible.
- mikejmoffitt 9y ago
  There is a little more CPU time, but the extended vertical blanking interval means there is a huge difference in video memory bandwidth, which is critical for a long DMA transfer from 68000-bus memory to VRAM through the Mega Drive's VDP. 60Hz V-blank DMA: 7524 50Hz V-blank DMA: 17622 That's at 320x224 resolution for both. I don't know how much this affects this one demo in particular, but for other things it can be a little annoying sometimes to be bandwidth-starved.
  - faragon 9y ago
    Thank you very much, with the available DMA bandwidth figures during V-blank you gave, I've found some VDP documentation: http://md.squee.co/VDP http://md.squee.co/VDP
amenghra 9y ago
Great work, congrats!
inDigiNeous 9y ago
Whew. Amazing work. Nothing else to add. Thank you.
panic 9y ago
Were there any alternatives/dead ends you went through to arrive at this technique, or any extensions you wanted to do but didn't find the time? Really amazing work BTW, this might be my favorite demo ever!
- jix 9y ago
  There weren't really any dead ends. Mostly because I started with a very simple naive way to draw polygons and improved it incrementally. I didn't implement all those steps, but convinced myself that they would work. I started with a generic plot-individual-pixels-into-tilemap routine. Going by tile-rows and columns with special casing solid tiles came next. That required "convexity" in x direction but at that point I was only thinking of triangles. Then I noticed that avoiding overdraw and working with a tesselation of the screen is probably faster. A that point I also extended it from triangles to polygons. While fleshing out the details of everything I noticed that I don't have to be exact for right-side edges if I draw the polygons in the right order. There actually was an extension I did, that was scrapped because it just didn't look good. At some point there was support for dithering. That helps with the low color precision of the Mega Drive (3-bit/channel). It only supported 50% checkerboard dither though, which looked odd when animated. I toyed with some ideas on how to improve upon that and discussed them within our demo group, but in the end the decision was to not use dithering.
Nition 9y ago
I had a couple of games on Mega Drive that did basic 3D, or seemed to. One was F1, where a few objects seemed to be true 3D. See the overbridge at 59s and then the long tunnel at 1:01 here for instance: https://youtu.be/qofonsN3Nwc?t=57 https://youtu.be/qofonsN3Nwc?t=57 The long tunnel is made of several short tunnels. The other was Gunstar Heroes, where the first boss is made of 3D cubes. See here at 4:00: https://youtu.be/9v3B1hzMwnQ?t=240 https://youtu.be/9v3B1hzMwnQ?t=240 I'm just interested if you know or can guess anything about how the "3D" might have been done in those.
- MBCook 9y ago
  I don't know about the F1 game but I can take a guess on Gunstar Heroes. I noticed the cubes are always aligned perfectly to the axis. And they have an isomorphic projection so the cube is always the same height (although that shouldn't be strictly necessary) as it's rotating. I also noticed the cubes never seem to get smaller if they are closer to the background. Because of this you could just have a series of sprites each showing the cube in a different angle of rotation. Now all you need to do is properly position a bunch of sprite (16 cubes + head) and it looks like a bunch of cubes that are actually drawn in 3-D. It wouldn't surprise me if they have some small table of the X/Y positions of the cubes precomputed so they don't have to do that in real time. In fact since every cube is always rotated at the same angle you could just have one sprite in the system table and update it every frame. That's my guess anyway. Clever sprite trickery. It wouldn't surprise me if F1 uses something closer to what is described in the article (although much less capable).
  - niftich 9y ago
    Your analysis appears correct, as several sources write that Gunstar Heroes uses multi-sprite bosses [1][2]. F1 on the Mega Drive owes its existence to an earlier game for the Atari ST, Vroom [5]. The brainchild behind that game, "Dan McRae", talks in a video interview [3] about how he arrived at that particular version of the game from his earlier revisions on older platforms -- where techniques shown in Lou's Pseudo 3d Page [4] apply, to more advanced techniques [6] similar to the ones presented in this submission. F1 on the Mega Drive was done by the same dev studio that collaborated with McRae on Vroom, and at least one of the same programmers, but presumably had to do some advanced tilemap trickery specific to the console. Unfortunately, compared to other games in this series, there is very little information on the technical aspects of the Mega Drive version. [1] http://www.hardcoregaming101.net/gunstarheroes/gunstarheroes.htm http://www.hardcoregaming101.net/gunstarheroes/gunstarheroes... [2] http://www.racketboy.com/retro/sega/genesis/best-sega-genesis-graphics-sound http://www.racketboy.com/retro/sega/genesis/best-sega-genesi... [3] https://youtu.be/ZTd-fFScLGA https://youtu.be/ZTd-fFScLGA [4] http://www.extentofthejam.com/pseudo/ http://www.extentofthejam.com/pseudo/ [5] https://youtu.be/ZTd-fFScLGA?t=7m33s https://youtu.be/ZTd-fFScLGA?t=7m33s [6] https://youtu.be/ZTd-fFScLGA?t=10m28s https://youtu.be/ZTd-fFScLGA?t=10m28s
deleted 9y ago
[deleted]
JohnBooty 9y ago
Not a question. But I just wanted to say that this sort of thing is amazing to me. I literally: 1. Saw this article headline about a polygon rendering engine on the Mega Drive 2. Thought, oh this is going to be good 3. Made some tea 4. Settled in to enjoy it. Not only did I love the demo and your article, you cleared up a longstanding mystery to me. I know that Another World (aka Out of This World) and Flashback (intro only) used similar techniques to render "canned" or "pre-baked" polygon animations on the Mega Drive, but I knew literally nothing about how that was possible. Thanks to you, now I have some kind of idea. Were you inspired by those games, to pull off this awesome effect in your demo? (BTW, you achieved a much better frame rate AND did it without borders... totally badass) Last but not least, thank you for the inspiration. I'm not a graphics programmer but I am a programmer and I have always been inspired by demos ever since the days of Future Crew. Coders like you inspire coders like me to better ourselves and be unafraid of challenges.
vanderZwan 9y ago
I don't write in Rust myself, but I'm sure many here would love to hear more about your experience with it
- jix 9y ago
  For this project I don't really have to say much about the rust side of it. There were no surprises. The only thing special I can think of is the excellent cross-compiling support. That came in handy as I had to produce windows binaries for the 3D artists.

Author here, happy to answer any questions you might have.

by jix 9y ago

Author here, happy to answer any questions you might have.

tawayway 9y ago

Congrats (and thanks) for the amazing prod :)

w0utert 9y ago

Absolutely awesome demo, thanks for the writeup of this impressive feat!

sergior 9y ago

I am trying to find my jaw. Haha no questions. Amazing stuff!

faragon 9y ago

Choosing 50 FPS instead of 60 was because needing to dedicate more CPU to each frame, or because another reason? P.S. Impressive demo, kudos :-)

shinymark 9y ago
PAL vs NTSC perhaps?
jix 9y ago
For the Mega Drive/Genesis the framerate depends on the region, matching the local video standard. The European Mega Drive uses PAL with 50Hz. As the biggest part (but not all) of the demoscene is based in Europe, most demos target PAL hardware. The same is true for our demo group. NTSC ports can be very difficult if not impossible as PAL often does have a slight advantage in CPU cycles per frame. This is also the case on the Mega Drive. Porting the polygon renderer shouldn't be a problem as it renders in an off-screen CPU RAM buffer. In the worst case it would have to skip more frames, having a lower effective framerate. A lot of the other effects have very critical timing though. I've been told that porting some of them to NTSC is just impossible.
mikejmoffitt 9y ago
There is a little more CPU time, but the extended vertical blanking interval means there is a huge difference in video memory bandwidth, which is critical for a long DMA transfer from 68000-bus memory to VRAM through the Mega Drive's VDP. 60Hz V-blank DMA: 7524 50Hz V-blank DMA: 17622 That's at 320x224 resolution for both. I don't know how much this affects this one demo in particular, but for other things it can be a little annoying sometimes to be bandwidth-starved.
- faragon 9y ago
  Thank you very much, with the available DMA bandwidth figures during V-blank you gave, I've found some VDP documentation: http://md.squee.co/VDP http://md.squee.co/VDP

amenghra 9y ago

Great work, congrats!

inDigiNeous 9y ago

Whew. Amazing work. Nothing else to add. Thank you.

panic 9y ago

Were there any alternatives/dead ends you went through to arrive at this technique, or any extensions you wanted to do but didn't find the time? Really amazing work BTW, this might be my favorite demo ever!

jix 9y ago
There weren't really any dead ends. Mostly because I started with a very simple naive way to draw polygons and improved it incrementally. I didn't implement all those steps, but convinced myself that they would work. I started with a generic plot-individual-pixels-into-tilemap routine. Going by tile-rows and columns with special casing solid tiles came next. That required "convexity" in x direction but at that point I was only thinking of triangles. Then I noticed that avoiding overdraw and working with a tesselation of the screen is probably faster. A that point I also extended it from triangles to polygons. While fleshing out the details of everything I noticed that I don't have to be exact for right-side edges if I draw the polygons in the right order. There actually was an extension I did, that was scrapped because it just didn't look good. At some point there was support for dithering. That helps with the low color precision of the Mega Drive (3-bit/channel). It only supported 50% checkerboard dither though, which looked odd when animated. I toyed with some ideas on how to improve upon that and discussed them within our demo group, but in the end the decision was to not use dithering.

Nition 9y ago

I had a couple of games on Mega Drive that did basic 3D, or seemed to. One was F1, where a few objects seemed to be true 3D. See the overbridge at 59s and then the long tunnel at 1:01 here for instance: https://youtu.be/qofonsN3Nwc?t=57 https://youtu.be/qofonsN3Nwc?t=57 The long tunnel is made of several short tunnels. The other was Gunstar Heroes, where the first boss is made of 3D cubes. See here at 4:00: https://youtu.be/9v3B1hzMwnQ?t=240 https://youtu.be/9v3B1hzMwnQ?t=240 I'm just interested if you know or can guess anything about how the "3D" might have been done in those.

MBCook 9y ago
I don't know about the F1 game but I can take a guess on Gunstar Heroes. I noticed the cubes are always aligned perfectly to the axis. And they have an isomorphic projection so the cube is always the same height (although that shouldn't be strictly necessary) as it's rotating. I also noticed the cubes never seem to get smaller if they are closer to the background. Because of this you could just have a series of sprites each showing the cube in a different angle of rotation. Now all you need to do is properly position a bunch of sprite (16 cubes + head) and it looks like a bunch of cubes that are actually drawn in 3-D. It wouldn't surprise me if they have some small table of the X/Y positions of the cubes precomputed so they don't have to do that in real time. In fact since every cube is always rotated at the same angle you could just have one sprite in the system table and update it every frame. That's my guess anyway. Clever sprite trickery. It wouldn't surprise me if F1 uses something closer to what is described in the article (although much less capable).
- niftich 9y ago
  Your analysis appears correct, as several sources write that Gunstar Heroes uses multi-sprite bosses [1][2]. F1 on the Mega Drive owes its existence to an earlier game for the Atari ST, Vroom [5]. The brainchild behind that game, "Dan McRae", talks in a video interview [3] about how he arrived at that particular version of the game from his earlier revisions on older platforms -- where techniques shown in Lou's Pseudo 3d Page [4] apply, to more advanced techniques [6] similar to the ones presented in this submission. F1 on the Mega Drive was done by the same dev studio that collaborated with McRae on Vroom, and at least one of the same programmers, but presumably had to do some advanced tilemap trickery specific to the console. Unfortunately, compared to other games in this series, there is very little information on the technical aspects of the Mega Drive version. [1] http://www.hardcoregaming101.net/gunstarheroes/gunstarheroes.htm http://www.hardcoregaming101.net/gunstarheroes/gunstarheroes... [2] http://www.racketboy.com/retro/sega/genesis/best-sega-genesis-graphics-sound http://www.racketboy.com/retro/sega/genesis/best-sega-genesi... [3] https://youtu.be/ZTd-fFScLGA https://youtu.be/ZTd-fFScLGA [4] http://www.extentofthejam.com/pseudo/ http://www.extentofthejam.com/pseudo/ [5] https://youtu.be/ZTd-fFScLGA?t=7m33s https://youtu.be/ZTd-fFScLGA?t=7m33s [6] https://youtu.be/ZTd-fFScLGA?t=10m28s https://youtu.be/ZTd-fFScLGA?t=10m28s

deleted 9y ago

[deleted]

JohnBooty 9y ago

Not a question. But I just wanted to say that this sort of thing is amazing to me. I literally: 1. Saw this article headline about a polygon rendering engine on the Mega Drive 2. Thought, oh this is going to be good 3. Made some tea 4. Settled in to enjoy it. Not only did I love the demo and your article, you cleared up a longstanding mystery to me. I know that Another World (aka Out of This World) and Flashback (intro only) used similar techniques to render "canned" or "pre-baked" polygon animations on the Mega Drive, but I knew literally nothing about how that was possible. Thanks to you, now I have some kind of idea. Were you inspired by those games, to pull off this awesome effect in your demo? (BTW, you achieved a much better frame rate AND did it without borders... totally badass) Last but not least, thank you for the inspiration. I'm not a graphics programmer but I am a programmer and I have always been inspired by demos ever since the days of Future Crew. Coders like you inspire coders like me to better ourselves and be unafraid of challenges.

vanderZwan 9y ago

I don't write in Rust myself, but I'm sure many here would love to hear more about your experience with it

jix 9y ago
For this project I don't really have to say much about the rust side of it. There were no surprises. The only thing special I can think of is the excellent cross-compiling support. That came in handy as I had to produce windows binaries for the 3D artists.