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physics2d module

The 2D rigid-body world: bodies and colliders on nodes, their velocities, raycasts and overlap queries. physics holds what spans both worlds.

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The 2D rigid-body world: bodies and colliders on nodes, their velocities, raycasts and overlap queries. physics holds what spans both worlds.

132 functions, 113 constants. Scripts reach it as physics2d::.

Acts on body2d, character2d, collider2d, follow2d, joint2d, softbody2d: those functions are also methods on the component's handle, without the node argument.

Functions

Argument kinds are the script values a call passes: node is a node handle, any a table or value of any kind, fn a callback.

function acts on what it does
aabb(node) -> float, float, float, float collider2d The world-space box the collider currently occupies, as its two opposite corners.
active_bodies() -> any — Every node whose body is awake this step: what a game loops over when it wants to touch only what is moving.
add_constant_force(node, float, float) body2d Push the body every step until the constant force is set back to zero; unlike an impulse this is spread over time.
add_constant_force_at_point(node, float, float, float, float) body2d Push at a world point every step, which also turns the body.
add_constant_torque(node, float) body2d Turn the body every step until the constant torque is set back to zero.
add_particle_force(node, int, any) softbody2d Push one particle with force each step until reset_softbody_forces.
add_softbody_force(node, any) softbody2d Push every free particle with force each step until reset_softbody_forces.
angular_velocity(node) -> float body2d How fast the body is spinning, in radians per second.
apply_force(node, float, float) body2d Push the body for the next step only; add_constant_force keeps pushing.
apply_force_at_point(node, float, float, float, float) body2d Push at a world point for the next step only, which also turns the body.
apply_impulse(node, float, float) body2d Add an instant change in momentum, as if the body were struck.
apply_impulse_at_point(node, float, float, float, float) body2d Strike the body at a world point, which spins it as well as moves it.
apply_particle_impulse(node, int, any) softbody2d Strike one particle.
apply_softbody_impulse(node, any) softbody2d Change every free particle's velocity by impulse at once, as a kick to the whole body.
apply_softbody_impulse_at(node, any, any, any) softbody2d Strike the particles within radius of point, less the further they are; a radius of 0 strikes them all.
apply_softbody_radial_impulse(node, any, any, any) softbody2d Push the particles within radius away from center, as a blast does.
apply_torque(node, float) body2d Turn the body for the next step only; add_constant_torque keeps turning it.
apply_torque_impulse(node, float) body2d Add an instant change in angular momentum, as if the body were spun.
attach_particle(node, int, node) softbody2d Tie one particle to a node's rigid body where it is now: the body and the particle pull on each other.
bodies() -> any — Every node with a rigid body, sorted.
broad_phase_aabb(node) -> float, float, float, float collider2d The box the broad phase files the collider under, which also reaches ahead by its body's speculative_distance.
closest_point(any) -> any — The closest point on any collider to a world point.
closest_points(node, node) -> any — The nearest point on each of two nodes' colliders, as #{ a, b }; nothing when they overlap.
collider_mass(node) -> float collider2d What this collider weighs, density and size together.
collider_mass_properties(node) -> any collider2d What this collider adds to its body, in its own space: #{ mass, center_of_mass, inertia }.
collider_mesh(node) -> any collider2d A voxel collider's outline as points and the segments between them, #{ points, indices }, for drawing it or for spawning the pieces it broke into.
collider_volume(node) -> float collider2d How much area the shape encloses.
collision_aabb(node) -> float, float, float, float collider2d The box the narrow phase tests the collider in: its shape's box grown by its collision_margin and the world's prediction distance.
combine_voxels(node, node) collider2d Tell two voxel colliders on one lattice about each other's cells, so a body sliding from one onto the other does not catch on the seam. Both must share a cell size and a rotation.
constant_force(node) -> float, float body2d The force every step integrates until it is set back to zero.
constant_torque(node) -> float body2d The torque every step integrates until it is set back to zero.
contacts(node) -> any collider2d Every contact point on this node's collider this step: #{ node, point, normal, impulse } each. Empty for a sensor, which has no contacts by definition.
crop_voxels(node, int, int, int, int) collider2d Empty every cell outside the cells from (min_x, min_y) to (max_x, max_y), both included. A range holding no filled cell leaves the grid as it was.
cut_softbody(node, any) -> any softbody2d Cut the body along a blade at once, as softbody_crossing reads it; answers a record for each piece it changed, the one on_tear hears.
detach_particle(node, int) -> bool softbody2d Untie one particle from every body it was attached to; answers whether it was attached.
distance(node, node) -> any — The gap between two nodes' colliders, zero when they touch.
effective_angular_inertia(node) -> float body2d The inertia the solver turns: zero with rotation locked, and on any body that is not dynamic.
effective_dominance(node) -> float body2d The dominance rapier will use for this body: its own group, or the rank every non-dynamic body outranks with.
effective_mass(node) -> any body2d The mass the solver pushes against along each world axis: zero along a locked axis, and on any body that is not dynamic.
gravity() -> float, float — The 2D world's gravity.
handles(node) -> any collider2d The rapier handles behind this node, its body and its colliders, as #{ body, colliders } of index and generation pairs. For matching a log line against rapier's own output.
has_pending_tears(node) -> bool softbody2d Whether some edge or cell is marked to tear at the end of the next step.
heightfield_hole(node, int) -> bool collider2d Whether a heightfield segment has no ground.
intersects(node, node) -> any — Whether two nodes' colliders overlap right now, sensor or not.
is_ccd_active(node) -> bool body2d Whether the body moved fast enough last step for rapier to sweep it, with or without continuous_collision.
is_moving(node) -> bool body2d Whether the body is awake and actually going somewhere.
is_on_floor(node) -> bool character2d Whether the last move ended with ground under the character's feet.
is_sleeping(node) -> bool body2d Whether the body is asleep and being skipped.
joint_force(node) -> any joint2d The force and the torque the joint held through the last step, #{ force, torque }. An articulation has none to read, and says so.
joint_state(node) -> any joint2d What the joint is doing: #{ status, angle, limit_impulses, motor_impulses, coordinates, velocities }, as in 3D: status is enabled, disabled, body_disabled or waiting; angle is a hinge's turn in radians; an articulation adds each free axis's coordinate and velocity.
kinetic_energy(node) -> float body2d The body's kinetic energy, for a rest test the solver agrees with.
linear_velocity(node) -> float, float body2d How fast the body is travelling, in units per second.
local_center_of_mass(node) -> any body2d Where the body's whole mass sits, in the body's own space.
max_contact_impulse(node) -> float body2d The hardest contact this body took in the last step, zero when nothing touched it.
move_character(node, float, float) -> any character2d Move the character by an offset, sliding along walls, climbing steps and staying on the ground: returns #{ x, y, on_floor, sliding, collisions }, each collision carrying the same fields as in 3D. Every solid collider of the character is swept. Call it from fixed_update.
next_position(node) -> any body2d The pose a kinematic body has been told to move to, as #{ position, rotation }.
overlap_aabb(any) -> any — Every collider whose bounds meet an axis-aligned box.
overlap_point(any) -> any — Every collider containing a world point: what a mouse click asks.
overlap_shape(any) -> any — Every collider a shape overlaps where it stands.
overlaps(node) -> [node] collider2d The nodes this one currently intersects; rapier reports a pair only when one of the two colliders is a sensor.
pin_particle(node, int) softbody2d Hold one particle where it is, which is how a cloth hangs from a hook.
pose_in_body(node) -> any collider2d Where the collider sits in its body's frame, as #{ position, rotation }; nothing for a collider with no body.
potential_energy(node) -> float body2d The body's gravitational potential energy over one step.
predict_position(node, float) -> any body2d Where the body will be after dt seconds at its current velocity, as #{ position, rotation }.
predict_position_with_forces(node, float) -> any body2d The same, with the forces already applied taken into account: where a thrust or a spring will have put it.
ragdoll(node, any?) -> any — Build a 2D ragdoll from the rig under this node: a body and a shape per bone, hinged to its parent's with the hinge's zero at the pose the rig is in. Options as in 3D, with shape one of capsule, rectangle or circle and axes records on rotation. Answers the body nodes it made.
raycast(any) -> any — The first collider a ray meets: #{ from = [x, y], dir = [x, y], max = 100.0, filter = #{ exclude = node } }. Returns #{ node, point, normal, distance }, or nothing.
raycast_all(any) -> any — Every collider a ray meets, nearest first.
remove_joint(node) joint2d Undo the node's joint, leaving both bodies free.
reset_follow(node) follow2d Forget what a pid follow summed, so it pulls from now as if it had just started.
reset_plasticity(node) softbody2d Undo every permanent set the body took: rest lengths, rest angles and rest shapes go back to how it was built, and it springs back from where it is.
reset_softbody_forces(node) softbody2d Take back every force add_softbody_force and add_particle_force gave the body.
set_angular_velocity(node, float) body2d Set how fast the body spins, in radians per second.
set_cell_tear_resistance(node, int, float) softbody2d The same for one cell's tear strain.
set_collider(node, any) collider2d Replace the node's collider from a collider2d table: kind, radius, size, friction, and the rest of the component's own vocabulary.
set_constant_force(node, float, float) body2d Replace the constant force with this one; zero stops the push.
set_constant_torque(node, float) body2d Replace the constant torque with this one; zero stops the turn.
set_edge_tear_resistance(node, int, float) softbody2d How many times the material's threshold one edge takes to tear; 1 is the material's.
set_gravity(float, float) — Set the 2D world's gravity, in units per second squared.
set_heightfield_hole(node, int, bool) collider2d Remove or restore one segment of a heightfield's ground, numbered from the first height.
set_joint_limits(node, string, float, float) joint2d Set how far one of the joint's free axes may travel; equal values lift the limit. Rewrites that axis's axes record.
set_linear_velocity(node, float, float) body2d Set how fast the body travels, in units per second.
set_motor_position(node, string, float, float, float) joint2d Drive one of the joint's free axes towards an angle or a distance, with a spring's stiffness and damping. Rewrites that axis's axes record.
set_motor_velocity(node, string, float, float) joint2d Drive one of the joint's free axes towards a speed: how a wheel is powered. Rewrites that axis's axes record.
set_particle_damaged(node, int, bool) softbody2d Mark one particle as damaged or mend it: a damaged particle tears as an outside one does, which seeds where a crack starts.
set_particle_position(node, int, any) softbody2d Put one particle at at with no change of velocity.
set_particle_target(node, int, any) softbody2d Move a held particle to at over the next step, with the velocity that takes, which is how a cloth is dragged.
set_particle_velocity(node, int, any) softbody2d Set one particle's velocity; a held one keeps moving at it.
set_softbody(node, any) softbody2d Build the node's soft body from a softbody2d table: kind, the shape rows, and the material rows.
set_voxel(node, int, int, bool) collider2d Fill or empty one cell of a voxel collider: digging a hole, or building a wall, while the game runs.
set_voxel_size(node, float, float) collider2d Resize every cell of a voxel collider, keeping which cells are filled.
shapecast(any) -> any — Sweep a shape along a direction until it hits something: a thick raycast.
sleep(node) body2d Put the body to sleep now.
softbody_area(node) -> float softbody2d How much area the body and every piece torn off it enclose right now, against softbody_rest_area for how far it is squeezed.
softbody_attachments(node) -> any softbody2d Every particle tied to a rigid body, as #{ particle, body, anchor, impulse }: the anchor in the body's own space, and the impulse the tie pulled with in the last substep.
softbody_boundary(node) -> any softbody2d The body's surface as particle indices: segments in 2D, triangles in 3D.
softbody_cell(node, int) -> any softbody2d Everything one cell holds: #{ particles, rest_volume, stiffness_scale, tear_resistance, stress, plastic_stretch }; stress is its strain as a fraction of tear_strain, plastic_stretch the rows of the permanent stretch of its rest shape.
softbody_cells(node) -> any softbody2d Every cell as its particle indices: triangles in 2D, tetrahedra in 3D.
softbody_center(node) -> any softbody2d The centre of mass of the body and its pieces, which is where it is when a deformable body has no one position.
softbody_contacts(node) -> any softbody2d What the body's surface touched in the last step: #{ edges, vertices, volumes }. Each edge and vertex contact with another soft body or itself is a pair of world points, the two witnesses; each volume contact is #{ center, normal, volume }.
softbody_crossing(node, any) -> any softbody2d The edges and cells a blade meets, #{ edges, cells }, without cutting: the blade is a segment's two points in 2D, a triangle's three in 3D.
softbody_edge(node, int) -> any softbody2d Everything one edge holds: #{ particles, kind, rest_length, initial_rest_length, plastic_strain, tension_only, softness_hz, softness_damping_ratio, tear_resistance, impulse, stress }; kind is structural or bending, and the softness is the edge's own or its kind's from the material.
softbody_edges(node) -> any softbody2d Every edge as the two particle indices it joins, in the order softbody_stress reports them.
softbody_mass(node) -> float softbody2d What the whole body weighs, every piece included.
softbody_particle(node, int) -> any softbody2d Everything one particle holds: #{ position, velocity, force, target, rest_position, initial_rest_position, mass, inverse_mass, pinned, damaged, on_surface }. force is what add_particle_force keeps on it, target where a held particle is going (nil when none), the two rest positions are relative to the rest centre of mass, before and after plastic flow, and inverse_mass is 0 while it is held.
softbody_particle_radius(node) -> float softbody2d How thick the particles are: what was asked for, or what the layout worked out.
softbody_particles(node) -> int softbody2d How many particles the body has, every piece torn off it included: a generator decides, not the author.
softbody_position(node, int) -> any softbody2d Where one particle is, in world space.
softbody_rest_area(node) -> float softbody2d How much they enclose at rest.
softbody_sleeping(node) -> bool softbody2d Whether the body has come to rest and stopped being simulated.
softbody_stress(node) -> any softbody2d Each edge's load as a fraction of its tear threshold, smoothed over tear_smoothing: 0 slack, 1 tearing; the larger of its stretch over tear_strain and its force over tear_force, and 0 while neither is set.
softbody_velocity(node, int) -> any softbody2d How fast one particle is moving, in world space.
softbody_volume_pieces(node) -> any softbody2d Each closed piece of the surface whose volume is held, as #{ particles, rest_volume, volume }; an open sheet has none.
solve_ik(node, float, float, any?) joint2d Move a reduced-coordinates chain so its last link reaches a world position, leaving every joint inside its limits. Options: rotation (radians to turn the link to), constrain (the world axes to match: x, y, rotation; the translation by default, every axis when rotation is given), damping (1.0), iterations (10), tolerance (0.001).
swept_aabb(node) -> float, float, float, float collider2d The box the collider covers over the next fixed step, from where it is to where its body's velocity and forces carry it.
tear_cell(node, int) softbody2d Tear one cell at the end of the next step: a particle near its middle splits across its main stretch.
tear_edge(node, int) softbody2d Tear one edge at the end of the next step.
tear_softbody(node, any, any) -> any softbody2d Tear the given edges and cells at once; answers a record for each piece it changed: #{ pieces, edges, cells, removed_edges, split_particles, inserted_particles, piece_particles, clusters, moved_joints }, the one on_tear hears. Particle indices are the torn piece's own; split_particles holds [copy, source] pairs, clusters #{ source, cluster, keeps_proxy }, and moved_joints the joint nodes a cluster split moved.
teleport(node, float, float, any?) body2d Move the body to a world position at once, clearing its velocity: what assigning the node's position cannot do, because the step writes that back every tick. #{ rotation = angle } turns it too, in radians.
time_of_impact(node, node, any) -> any — When two moving colliders would meet, given each one's velocity: #{ velocity_a = [..], velocity_b = [..], max_time = 1.0 }. Nothing when they never do.
time_since_can_sleep(node) -> float body2d Seconds the body has spent under its sleep thresholds; it sleeps once this reaches time_to_sleep.
total_inertia(node) -> float body2d The body's resistance to spin, colliders included.
total_mass(node) -> float body2d The body's total mass: its mass when it states one, or what its colliders weigh.
unpin_particle(node, int) softbody2d Let a held particle go; it keeps the velocity it had.
velocity_at_point(node, float, float) -> float, float body2d How fast a world point on the body is moving, spin included.
voxel(node, int, int) -> bool collider2d Whether one cell of a voxel collider is filled.
voxel_at(node, float, float) -> int, int collider2d The cell a world position falls in, as two whole numbers.
voxel_size(node) -> any collider2d How big one cell of a voxel collider is, along each axis.
wake_all() — Wake every sleeping body in the 2D world.
wake_softbody(node) softbody2d Start simulating a resting body again.
wake_up(node) body2d Wake the body, so the next step moves it.
world_center_of_mass(node) -> any body2d Where the body's whole mass sits, in world space.

Constants

name value
AXIS_ROTATION rotation
AXIS_X x
AXIS_Y y
BIND_CELLS cells
BIND_NEAREST nearest
BIND_PARTICLES particles
BODY_DYNAMIC dynamic
BODY_KINEMATIC kinematic
BODY_KINEMATIC_VELOCITY kinematic_velocity
BODY_STATIC static
CELL_COROTATIONAL corotational
CELL_NEO_HOOKEAN neo_hookean
CELL_VOLUME volume
COLLIDE_DYNAMIC_DYNAMIC dynamic_dynamic
COLLIDE_DYNAMIC_KINEMATIC dynamic_kinematic
COLLIDE_DYNAMIC_STATIC dynamic_static
COLLIDE_KINEMATIC_KINEMATIC kinematic_kinematic
COLLIDE_KINEMATIC_STATIC kinematic_static
COLLIDE_STATIC_STATIC static_static
COMBINE_AVERAGE average
COMBINE_CLAMPED_SUM clamped_sum
COMBINE_GEOMETRIC_MEAN geometric_mean
COMBINE_MAX max
COMBINE_MIN min
COMBINE_MULTIPLY multiply
DRIVE_FOLLOW follow
DRIVE_MOTORS motors
DRIVE_NONE none
EDGES_CHAIN chain
EDGES_MESH mesh
EDGES_OUTLINE outline
EVENT_COLLISION collision
EVENT_CONTACT_FORCE contact_force
FILL_SOLID solid
FILL_SURFACE surface
FIT_AABB aabb
FIT_CONVEX_DECOMPOSITION convex_decomposition
FIT_CONVEX_HULL convex_hull
FIT_OBB obb
FLOW_BOTH both
FLOW_COMPRESSION compression
FLOW_TENSION tension
FOLLOW_PD pd
FOLLOW_PID pid
IGNORE_DYNAMIC dynamic
IGNORE_KINEMATIC kinematic
IGNORE_SENSORS sensors
IGNORE_SOLIDS solids
IGNORE_STATIC static
JOINT_BODY_DISABLED body_disabled
JOINT_DISABLED disabled
JOINT_ENABLED enabled
JOINT_FIXED fixed
JOINT_GENERIC generic
JOINT_GROOVE groove
JOINT_HINGE hinge
JOINT_ROPE rope
JOINT_SLIDER slider
JOINT_SPRING spring
JOINT_WAITING waiting
LENGTHS_ABSOLUTE absolute
LENGTHS_RELATIVE relative
METHOD_EXACT exact
METHOD_VHACD vhacd
METHOD_VOXELS voxels
MOTOR_MODEL_ACCELERATION acceleration
MOTOR_MODEL_AUTO auto
MOTOR_MODEL_FORCE force
MOTOR_OFF off
MOTOR_POSITION position
MOTOR_VELOCITY velocity
ORIENTATION_AUTO auto
ORIENTATION_SHELL shell
ORIENTATION_SOLID solid
SHAPE_CAPSULE capsule
SHAPE_CIRCLE circle
SHAPE_CONVEX_DECOMPOSITION convex_decomposition
SHAPE_CONVEX_HULL convex_hull
SHAPE_CONVEX_POLYGON convex_polygon
SHAPE_FIT fit
SHAPE_HEIGHTFIELD heightfield
SHAPE_MATCHING_AUTO auto
SHAPE_MATCHING_OFF off
SHAPE_MATCHING_ON on
SHAPE_POLYLINE polyline
SHAPE_RECTANGLE rectangle
SHAPE_SEGMENT segment
SHAPE_TRIANGLE triangle
SHAPE_TRIANGLE_MESH triangle_mesh
SHAPE_VOXELIZED_MESH voxelized_mesh
SHAPE_VOXELIZED_POINTS voxelized_points
SHAPE_VOXELS voxels
SHAPE_WORLD_BOUNDARY world_boundary
SOFT_CIRCLE circle
SOFT_CUSTOM custom
SOFT_GRID grid
SOFT_OUTLINE outline
SOFT_POLYGON polygon
SOFT_POLYLINE polyline
SOFT_ROPE rope
SOFT_SOLVER_CONSTRAINTS constraints
SOFT_SOLVER_FEM fem
SOFT_TRIANGLE_MESH triangle_mesh
SOFT_VOLUMETRIC volumetric
SWEEP_CONVERGED converged
SWEEP_FAILED failed
SWEEP_OUT_OF_ITERATIONS out_of_iterations
SWEEP_PENETRATING penetrating
TENSION_ALL all
TENSION_LISTED listed
TENSION_NONE none
TEST_BOTH both
TEST_EITHER either