Week 2 - How do you Jump?

Bit of a busy week between Holiday plans and job search shenanigans, but we still managed to make a chunk of progress in between everything. My primary goal for the week was to sort out the jump state and the various mechanics attached to that. ie; Jump, spin jump, fall, and land. Setting up the states themselves and the animations was simple enough. just more of what we already did last week, but when it came to figuring out the specific jump physics I came to an interesting realization. For how many years I've been working as a gameplay programmer, I've never actually programmed a jump before that wasn't just a basic "apply upward force, add gravity until you fall" sort of thing. Anyone who has played Super Metroid (or any Nintendo platformer for that matter) knows that that's not how it works; jumps are dynamic, you go higher when you hold the button down longer and you can short-hop by just tapping the button briefly.

So after setting up the basic framework, I had a bit of homework to do. Luckily this is a very well explored topic and I was able to find a GDC talk from 2016 going over exactly what I needed to know.

​Here's a link for anyone who's interested: https://www.youtube.com/watch?v=hG9SzQxaCm8

Pretty simple setup after do we our math magic; we apply an upward force right when we enter the jump state, and then apply one of two constant gravity values depending on whether or not the player is holding down the jump button. Basically, gravity gets a lot heavier when you let go of the button. Once the player's vertical velocity becomes negative, we swap to the falling state and then apply a different gravity value that's slightly heavier to give the jump a bit more weight. Once we hit the ground, we swap to the Landing state just until the animation finishes before going back to Standing.

Now technically I'm not sure this is exactly how they handle jump momentum in Super Metroid, based on my observations they might literally just zero out the player's vertical velocity when they release the jump button, but I feel like this solution is probably more valuable for me in terms of future projects. 

Speaking of Super Metroid, I noticed an interesting quirk while I was testing the game's jump feel against my own;  the game seems to differentiate between when the player falls after jumping and when they fall from a standing state. Specifically, it has a different animation and the maximum fall speed is different, so I set up my system to work similarly:

Last up for the week was the spin jump. This is the state you enter when you jump while moving as opposed to standing still, and it comes with a few distinctions. First, you have a constant forward velocity while spin jumping, even if you stop pressing forward on your controller. Second, there is no turn animation for spin jumping; you instantly flip around and move in the opposite direction instead. And Third, the Spin jump has a slightly different animation when landing than a normal jump. There a few other notable differences as well, but those won't be important until I get to things like aiming and wall jumping. Because the rest of the jump physics are the same though, getting this state working was a pretty simple task.

And that's about it for now. I need to adjust the normal jump slightly in order to add in the separate animation the plays when you start moving forward, but besides that my main plans for next week are to get crouching and morphball working, and maybe start on figuring out the aiming logic.

See you next time.