Expand description
Gravitas is a collection of equations for making UI elements move in response to touch gestures.
There are also implementations for Java and JavaScript (which has some interactive examples).
Each simulation models a single value and generally has a setup function that takes the initial position and velocity. Normally you would compute these in response to a touch gesture ending. All of the simulations are parametric over time and have been algebraically integrated (rather than using a numerical integration method at runtime). The advantage of algebraic integration is lower CPU overhead, and no odd behavior if frames are dropped.
Structs§
- Friction
- a position with velocity that slows down due to drag.
- Gravity
- a position under the influence of gravity (or any other constant acceleration), as defined by Newton’s 2nd Law:
F = ma. - Pager
- Pager is similar to
Scroll, except it contains user supplied snap points which the simulation will be attracted to. These snap points are supplied to the constructor. - Pager
Snap Point - A SnapPoint is either an end point or a point of attraction. Every pager needs at least two snap points to define the extents
- Scroll
- a combination of friction and springs to create a touch-driven scrolling simulation.
- Spring
- a position controlled by a spring as defined by Hooke’s law,
F = -kx * cv.
Enums§
- Pager
Snap Query - Any number can be either between two snap points, or beyond one of the extents.
Traits§
- Simulation
- common methods implemented by every simulation allowing easy integration into an animation system.