Springs and curves
Learning paths through this topic
Stop a dialogue box from jumping and words from hopping lines while they type
Text that appears letter by letter often has a word that starts on one line and suddenly leaps to the next, and the box grows in jerks as lines are added. This shows how to lay the whole text out first and reveal it inside that fixed layout.
Swing a door open so it knocks the wall once or twice and then stays still
A door that stops dead at the wall feels stiff, and one that keeps trembling forever or sinks into the wall looks broken. Here is how to let it hit the stop, bounce back less each time, and come to a real rest.
Tilt an item you drag across the inventory by how fast the cursor moves
A picked-up item that follows the cursor stiffly feels dead, but tilting it by raw mouse movement makes it twitch wildly. Here is how to turn cursor speed into a gentle tilt that settles with a small wobble when you stop.
Drop an item that bounces a few times and then really comes to rest
A dropped coin or ball that bounces by flipping its speed each frame either jitters on the floor forever or sinks into it, and its timing depends on the frame rate. Here is how to know the exact moment of every bounce and when to stop.
Make dropped items bob and spin out of step, and only once they lie still
A pile of loot where every item rises and falls at the same moment looks like one machine, and things that already bob while still flying through the air look wrong. Here is how each item gets its own rhythm without random numbers and starts the bobbing only when it has landed.
Make enemies tilt back from a hit, heavier ones less, without folding flat
A little recoil makes a hit feel solid. But a heavy ogre should not wobble like a bush, and a fast flurry of hits must not push an enemy through the ground. Here is how to scale the reaction by weight and keep a pile-up of hits believable.
Fill an experience bar through two or three level-ups from one big reward
After a boss, the reward may be enough for several levels at once. A bar that just slides to the new fill level shows the wrong picture, and level-up messages can get lost or fire twice. Here is how to run the bar through every level and announce each exactly once.
Shake the screen for explosions: stronger when near, stacking, never endless
A shake that is the same size for every blast, or that doubles whenever two things go off together, is either dull or sickening. Here is a way to scale it by distance, let several blasts add up to a limit, and fade out so the picture ends perfectly still.
Keep a fairy companion floating in a lazy figure eight that trails behind the hero
A companion that sits rigidly on the hero looks pasted on, one that drifts randomly looks lost. A gentle looping flight that trails the hero, hangs back when they run, and calms down on arrival feels alive. Here is how to compose these three motions.
Make a fishing float twitch with small nibbles and then plunge on the real bite
Waiting for a fish should have tension: tiny dips that fade, another tug, and then the big one. Each tug has to ripple out and calm down on its own while the next one adds on top. This shows how to build it so it looks the same at any speed of play.
Flip a loot card over with a bounce and never show its back mirrored
Turning a card by squeezing it flat and growing it again looks easy, until the picture on the far side appears backwards, or a lively bounce spins the card past the point where the wrong side shows. Here is how to pick the side and how bouncy the flip may be.
Let crates and logs float at the right depth and bob on waves without sinking or flying
A floating crate that sits on top of the water like a table, sinks like a stone or jumps out of the lake on the first splash is a common bug in sandbox worlds. Here is how the upward push grows as it sinks, so each thing finds its own level.