Springs and curves
Learning paths through this topic
Stop a temperature gauge needle from trembling while still following real changes
In a survival game the body temperature jitters slightly every moment because of wind, fire distance and biome blending, and the needle shakes with it. Here is how to calm the needle so it holds still on noise yet follows real warming and cooling without a delay you can feel.
Throw an item in an arc that peaks where you choose and lands on time
Loot flying to a chest, a potion thrown at a target, a frog jumping to a lily pad: you know where it starts and ends and want a nice arc of a certain height in a certain time, with any gravity feeling. Here is how to work out the arc that fits.
Make villagers startle one after another, spreading outward from a loud event
When a dragon roars or a bell rings, a crowd that all jumps in the same frame looks like a stage trick. The reaction should travel outward, weaker with distance, and the far corners should stay calm. Here is a way to give every person their delay, height and a fixed hop that fits any crowd size.
Lunge an attacker at its target, stop in front of it and step back
In turn-based fights the attacker dashes forward, strikes and returns. Moving to the target's centre puts one sprite inside the other, and an attacker already standing close would run backwards first. Here is how to find the stopping spot, time the hit and glide home.
Show ripples where the player wades or throws a stone, with a fixed number of rings
Every footstep in a shallow stream could create a new ring, and soon the screen is full of them and the game slows down. Here is a small fixed pool of rings that reuses the oldest, skips needless doubles and fades each ring out the way water does.
Fade between weather types, even when the weather changes again halfway
Clear to rain is easy; clear to rain to snow within a minute often leaves the world too dark, too bright or with a pop. Here is a way to blend any number of weather types so the mix always adds up and every change continues from where it is.
Let wind gusts sweep across the trees, and turn the wind without the forest jumping
Trees that all sway in the same beat look dead, and when the wind direction changes in a weather system every tree in the world lurches at the same instant. Here is how to make waves that visibly travel with the wind and turn it smoothly.
Pop a menu or shop window open with a bounce that does not flip it when closing
A little overshoot makes a window feel alive, but the same bounce on the way out can push it past nothing and show it mirrored for a moment, or leave an invisible window that still catches clicks. Here is how to open lively and close cleanly.