A real-time rigid body 2D physics engine for the web. Development is still active and many features are being added including arbitrary convex polygons. Checkout my game at https://buildhead.web.app/ to see it in action.
Pulsition simulates physics using a local solver to solve pairwise constraints. Multiple iterations are used to solve competing constraints. Pulsition is implemented in a low-level manner using typedArrays to increase performance. It does not support variable-rate time steps. Only two shapes are currently supported Circle and Obround. Convex polygons are available but not completely supported. Axis-aligned bounding boxes are supported to observe the position of objects. Warm-starting is used by default to significantly reduce the number of iterations needed to solve competing constraints at the cost of accuracy. Speculative contacts are used by default to prevent tunnelling also at the cost of accuracy. There are two main type of constraints supported: collisions and joints. Colliding pairs can be filtered using groups. Joints can be motorized. Pulsition does not render graphics and there is no testing UI. I recommend using WebGL for graphics rendering. If you require basic rendering for testing, please contact me.
Body: a rigid body that Pulsition attempts to simulate.
Body reference: a uniquely identifying number used to refer to a specific body.
The pw.create() method creates bodies that are simulated by Pulsition.
pw.create(def)
def: the body definition.
The body reference of the body created.
The pw.createContacts() method creates collision constraints between the bodies specified.
pw.createContacts(bodyReference, groups)
bodyReference: the body reference of the body with which collision constraints will be created.
groups: an array of numbers, for each body with a group contained in the groups array a collision contraint will be created.
None.
The pw.update() method simulates one time step. Usually it is called repeatedly at fixed time steps.
pw.update()
None.
None.
The body definition is the object that is passed to the pw.create() method to define the properties of the body being created. Any unrecognized properties are ignored. It must contain the following properties:
form: either pw.CIRCLE_FORM, pw.PLANE_FORM, pw.POLYGON_FORM or pw.AABB_FORM. pw.CIRCLE_FORM creates a circular body. pw.PLANE_FORM creates an obround body. pw.POLYGON_FORM is not fully supported. pw.AABB_FORM creates an axis-aligned bounding box that is not physically simulated. If pw.CIRCLE_FORM then x, y and radius must also be specified. If pw.PLANE_FORM then width and vertices must also be specified. If pw.AABB_FORM then vertices must also be specified. If pw.POLYGON_FORM then vertices must also be specified.
type: either pw.MOVABLE_TYPE or pw.FIXED_TYPE. pw.MOVABLE_TYPE specifies a normal body that can move. pw.FIXED_TYPE specifies a object that will never move, suitable for simulating massive objects like the earth. If pw.MOVABLE_TYPE then density must also be specified.
It may contain the following properties:
density: a number that specifies the density of the body, it must be postive.
group: a number that specifies the group of the body. Used to filter colliding pairs.
userFloats: a array of numbers. Can contain any numbers and be any length. The array can be retreived with pw.getUserFloats() and modified with pw.setUserFloats() though length cannot be changed after the body is created.
staticFriction: a number that is used to calculate the amount of static friction between two colliding pairs, it must be positive. The static friction between two bodies is calculated by the average of their staticFriction.
kineticFriction: a number that is used to calculate the amount of kinetic friction between two colliding pairs, it must be positive. The kinetic friction between two bodies is calculated by the average of their kineticFriction.
linearVelocityResistance: a number that specifies the amount of dampening applied to linear velocity of the body per time step. It must be greater than or equal to 0 and less than or equal to 1. It is used to simulate things such as air resistance. The closer it is to 0 the more resistance will be applied. If 0 then the object will not move linearly.
rotationalVelocityResistance: a number that specifies the amount of dampening applied to rotational velocity of the body per time step. It must be greater than or equal to 0 and less than or equal to 1. It is used to simulate things such as rolling resistance. The closer it is to 0 the more resistance will be applied. If 0 then the object will not rotate.
x: a number that specifies the position of the center of the body in the x-axis.
y: a number that specifies the position of the center of the body in the y-axis.
radius: a number that specifies the radius of the body, it must be positive.
width: a number that specifies the width of the body, it must be a positive.
vertices: a 2D array that specifies the positions of the vertices of the body. The length of each subarray must be equal to 2, each element a number that specifies a position in the x and y axis respectively. If the form property of the body definition is equal to pw.PLANE_FORM then the length of vertices must be equal to 2, each subarray specifying the position of the two ends of the body. If the form property of the body definition is equal to pw.POLYGON_FORM then the length of vertices must be more than 3, each subarray specifying the position of each vertex of the body in counter-clockwise direction. If the form property of the body definition is equal to pw.AABB_FORM then the length of vertices must be equal to 2, each subarray specifying the position of the minimum and maximum vertex respectively.
If you want to discuss or use this repository please contact me.