The Physics behind Video Games
By Laurin Fisher
Nov
26
Slopes/Stairs
There are actually a crazy amount of different ways to do stairs, and it really varies which way is better for which type of game.
For example, in a first person shooter game you want stairs to be realistic, but in reality the player isn't really paying much attention to the physics of the stairs. They are paying attention to not getting shot! You can't see the character's feet in this case, and snapping to each stair would prove to be a hindrance. It is far better in this case to treat stairs as a slope, something the computer has less trouble computing and is way faster for character movement.
0. Treat Stairs as slopes
This method is just like it sounds. It is actually not a bad method in video games. Yes it might seem cheap, but in reality it is used for really good reasons.
Just like the first person shooter game mentioned above, this method is usually used in terms of speed and smoothness.
Game Example: Nintendo calculates slopes as stairs in at least two of their Zelda games. In Windwaker I asked my brother to stand his character on the stairs and give me a good side view angle.
(Picture of my brother playing Windwaker, taken by me)
As you can see, his leg goes through the stairs as if he is walking up a slope instead. I asked him to do the same for his new favorite game, Hyrule Warriors (also a zelda game). He was surprised it did the same and it was just released in September.
Something to note here, my brother has played this part of the game numerous times and has NEVER noticed that the stairs weren't actually stairs. Keep this in mind!! Professional games do this with no penalty! They get player satisfaction because of it's speed and smoothness. It doesn't draw attention to itself and usually you only see the back of the player, so it looks realistic enough.
It is especially important in games like this, when villains can fight you on the stairs. You don't want restricted movement!
1. Snapping
By snapping I mean having the character's feet be realistically on the stairs.
Game Example: Mario Sunshine does this. Mario runs up the stairs pretty quickly and you can see the him shaking as he is snapping to each step appropriately.
(Picture of Mario Sunshine, again taken by me)
The only way I can think of doing this is having a coordinate system on the stairs. As the player moves to the next step up, they are snapped up by a certain height.
2. Ladder
There also are those stairs in games where the player can move up or down, sort of like a ladder. And the character has to run up every single stair. I wouldn't recommend this because it is slow.
3. Animation
Another possibility is having an animation only for the stairs. When the player hits the bottom the animation plays then the player is able to move again, now at the top of the stairs. By doing this, speed nor realism takes a tole, however you did just strip away some game play. But it is an option! The video game Animal Crossing uses this!
Further reading
Nov
26
Sum up of Stairs
There are many ways to implement stairs in your game. The most widely used in a 3D world would probably be to treat them as slopes, however other options exist, such as snapping, animation, and ladder effects.