Description
Provides simple physics functionality for tweening an Object’s x
and y
coordinates (or left
and top
) based on a combination of velocity
, angle
, gravity
, acceleration
, accelerationAngle
, and/or friction
. It is not intended to replace a full-blown physics engine and does not offer collision detection, but serves as a way to easily create interesting physics-based effects with the GreenSock Animation Platform.
Parameters are not intended to be dynamically updateable, but one unique convenience is that everything is reverseable. So if you spawn a bunch of particle tweens, for example, and throw them into a timeline, you could simply call reverse()
on the timeline to watch the particles retrace their steps right back to the beginning. Keep in mind that any easing equation you define for your tween will be completely ignored for these properties.
-
velocity
: Number - The initial velocity of the object measured in pixels per time unit. (Default:0
) -
angle
: Number - The initial angle (in degrees) at which the object should travel. This only matters when avelocity
is defined. For example, if the object should start out traveling at -60 degrees (towards the upper right), theangle
would be-60
. (Default:0
) -
gravity
: Number - The amount of downward acceleration applied to the object, measured in pixels per second. You can either usegravity
oracceleration
, not both becausegravity
is the same thing asacceleration
applied at anaccelerationAngle
of90
. Think of gravity as a convenience property that automatically sets theaccelerationAngle
for you. (Default:null
) -
acceleration
: Number - The amount of acceleration applied to the object, measured in pixels per second, it would be measured per frame). To apply the acceleration in a specific direction that is different than the angle, use theaccelerationAngle
property. You can either usegravity
oracceleration
, not both becausegravity
is the same thing asacceleration
applied at anaccelerationAngle
of90
. (Default:null
) -
accelerationAngle
: Number - The angle at which acceleration is applied (if any), measured in degrees. So if, for example, you want the object to accelerate towards the left side of the screen, you’d use anaccelerationAngle
of180
. If you define agravity
value, it will automatically set theaccelerationAngle
to90
(downward). (Default:null
) -
friction
: Number - A value between 0 and 1 where 0 is no friction, 0.08 is a small amount of friction, and 1 will completely prevent any movement. This is not meant to be precise or scientific in any way, but it serves as an easy way to apply a friction-like physics effect to your tween. Generally it is best to experiment with this number a bit - start with very small values like 0.02. Also note that friction requires more processing than physics tweens without any friction. (Default:0
) -
xProp
: String - By default, thex
property of the target object is used to control x-axis movement, but if you’d prefer to use a different property name, usexProp
likexProp: "left"
. (Default:"x"
) -
yProp
: String - By default, they
property of the target object is used to control y-axis movement, but if you’d prefer to use a different property name, useyProp
likeyProp: "top"
. (Default:"y"
)
Usage
gsap.to(element, {duration: 2, physics2D: {velocity: 300, angle: -60, gravity: 400}});
//or
gsap.to(element, {duration: 2, physics2D: {velocity: 300, angle: -60, friction: 0.1}});
//or
gsap.to(element, {duration: 2, physics2D: {velocity: 300, angle: -60, acceleration: 50, accelerationAngle: 180}});
Physics2DPlugin is a Club GreenSock membership benefit. You must have a valid membership to use this class without violating the terms of use. Visit the club page to sign up or get more details.
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