5 ms·

Guide to implementing 2D platformers (2012)

122 points by vvoruganti 2y ago

jonathanyc 2y ago
I like the idea of a guide like this. Reminds me of “Implementation of Hex Grids,” another high quality game-related guide: https://www.redblobgames.com/grids/hexagons/implementation.html https://www.redblobgames.com/grids/hexagons/implementation.h... and before that, “Beej’s Guide to Network Programming”: https://beej.us/guide/bgnet/ https://beej.us/guide/bgnet/
matheusmoreira 2y ago
> I believe that Mega Man actually employs infinite acceleration, that is, you’re either stopped or on full speed Yeah, acceleration is essentially infinite. https://tasvideos.org/GameResources/NES/Rockman/Data https://tasvideos.org/GameResources/NES/Rockman/Data When moving horizontally there's very small lag at the start and then he accelerates to full speed pretty much instantly. When moving vertically by jumping, his speed is straight up set to some constant. There is downwards deceleration by gravity though, leading to "fall faster" tricks: https://tasvideos.org/GameResources/NES/Rockman#FallingFaster https://tasvideos.org/GameResources/NES/Rockman#FallingFaste...
henning 2y ago
For making the game more fun, you can then add features that are now standard/expected like coyote time. https://www.youtube.com/watch?v=97_jvSPoRDo https://www.youtube.com/watch?v=97_jvSPoRDo
deleted 2y ago
[deleted]
dang 2y ago
Related. Others? Guide to implementing 2D platformers (2012) - https://news.ycombinator.com/item?id=31450218 https://news.ycombinator.com/item?id=31450218 - May 2022 (37 comments) A guide to implementing 2D platformers - https://news.ycombinator.com/item?id=10202275 https://news.ycombinator.com/item?id=10202275 - Sept 2015 (32 comments) The guide to implementing 2D platformers - https://news.ycombinator.com/item?id=4065033 https://news.ycombinator.com/item?id=4065033 - June 2012 (2 comments) The Guide to Implementing 2D Platformers - https://news.ycombinator.com/item?id=4005883 https://news.ycombinator.com/item?id=4005883 - May 2012 (2 comments)
- naveen99 2y ago
  [flagged]
moth-fuzz 2y ago
I’ve implemented platformer collision dozens of times now and the only way I’ve found it to be genuinely smooth is to do it one pixel at a time, just like the author suggests. But something always bugs me about that - we know the closest edge of the closest obstacle, we know the vector of the player’s motion, by all accounts we should be able to calculate the point of contact in one go without doing any substeps. And yet, doing it in one pass always seems to result in a myriad of edge cases (literal!) that break the whole thing, unless you do heavy preprocessing, converting your tiles to a graph of lined surfaces, etc etc.
teddyh 2y ago
> Type #1: Tile-based (pure) > Character movement is limited to tiles, so you can never stand halfway between two tiles. […] > Examples: Prince of Persia That is absolutely false. You can stand on any pixel in Prince of Persia. It’s when I find stupid errors like these that I start to question the entire article they appear in.
- nurettin 2y ago
  As I remember, when you step slowly from the middle of a tile, you always end up on the edge of that tile. And if there is a chasm and you try to step once again, you almost trip and regain balance. If there is no chasm, you step to the middle of the next tile.
  - teddyh 2y ago
    IIRC, you can adjust your position quite precisely by crouching, which has a side effect of making you move forward a tiny little bit. Yes, stepping towards a chasm will make you stop at the edge, but that does not alter the fact that your position is definitely not clipped to fixed steps, as the article erroneously claims.
deleted 2y ago
[deleted]

122 points by vvoruganti 2y ago

I like the idea of a guide like this. Reminds me of “Implementation of Hex Grids,” another high quality game-related guide: https://www.redblobgames.com/grids/hexagons/implementation.html https://www.redblobgames.com/grids/hexagons/implementation.h... and before that, “Beej’s Guide to Network Programming”: https://beej.us/guide/bgnet/ https://beej.us/guide/bgnet/

matheusmoreira 2y ago

> I believe that Mega Man actually employs infinite acceleration, that is, you’re either stopped or on full speed Yeah, acceleration is essentially infinite. https://tasvideos.org/GameResources/NES/Rockman/Data https://tasvideos.org/GameResources/NES/Rockman/Data When moving horizontally there's very small lag at the start and then he accelerates to full speed pretty much instantly. When moving vertically by jumping, his speed is straight up set to some constant. There is downwards deceleration by gravity though, leading to "fall faster" tricks: https://tasvideos.org/GameResources/NES/Rockman#FallingFaster https://tasvideos.org/GameResources/NES/Rockman#FallingFaste...

henning 2y ago

For making the game more fun, you can then add features that are now standard/expected like coyote time. https://www.youtube.com/watch?v=97_jvSPoRDo https://www.youtube.com/watch?v=97_jvSPoRDo

deleted 2y ago

[deleted]

dang 2y ago

Related. Others? Guide to implementing 2D platformers (2012) - https://news.ycombinator.com/item?id=31450218 https://news.ycombinator.com/item?id=31450218 - May 2022 (37 comments) A guide to implementing 2D platformers - https://news.ycombinator.com/item?id=10202275 https://news.ycombinator.com/item?id=10202275 - Sept 2015 (32 comments) The guide to implementing 2D platformers - https://news.ycombinator.com/item?id=4065033 https://news.ycombinator.com/item?id=4065033 - June 2012 (2 comments) The Guide to Implementing 2D Platformers - https://news.ycombinator.com/item?id=4005883 https://news.ycombinator.com/item?id=4005883 - May 2012 (2 comments)

naveen99 2y ago
[flagged]

moth-fuzz 2y ago

I’ve implemented platformer collision dozens of times now and the only way I’ve found it to be genuinely smooth is to do it one pixel at a time, just like the author suggests. But something always bugs me about that - we know the closest edge of the closest obstacle, we know the vector of the player’s motion, by all accounts we should be able to calculate the point of contact in one go without doing any substeps. And yet, doing it in one pass always seems to result in a myriad of edge cases (literal!) that break the whole thing, unless you do heavy preprocessing, converting your tiles to a graph of lined surfaces, etc etc.

teddyh 2y ago

> Type #1: Tile-based (pure) > Character movement is limited to tiles, so you can never stand halfway between two tiles. […] > Examples: Prince of Persia That is absolutely false. You can stand on any pixel in Prince of Persia. It’s when I find stupid errors like these that I start to question the entire article they appear in.

nurettin 2y ago
As I remember, when you step slowly from the middle of a tile, you always end up on the edge of that tile. And if there is a chasm and you try to step once again, you almost trip and regain balance. If there is no chasm, you step to the middle of the next tile.
- teddyh 2y ago
  IIRC, you can adjust your position quite precisely by crouching, which has a side effect of making you move forward a tiny little bit. Yes, stepping towards a chasm will make you stop at the edge, but that does not alter the fact that your position is definitely not clipped to fixed steps, as the article erroneously claims.

deleted 2y ago

[deleted]