Collision object

Namespace: physics Language: Lua Type: Defold Lua File: physics_ddf.proto Source: engine/gamesys/proto/gamesys/physics_ddf.proto

Collision object physics API documentation

API

angular_damping

Type: PROPERTY The angular damping value for the collision object. Setting this value alters the damping of angular motion of the object (rotation). Valid values are between 0 (no damping) and 1 (full damping).

Examples

How to decrease a collision object component’s angular damping:

-- get angular damping from collision object "collisionobject" in gameobject "floater"
local target = "floater#collisionobject"
local damping = go.get(target, "angular_damping")
-- decrease it by 10%
go.set(target, "angular_damping", damping * 0.9)

angular_velocity

Type: PROPERTY The current angular velocity of the collision object component as a vector3. The velocity is measured as a rotation around the vector with a speed equivalent to the vector length in radians/s.

Replaces: request_velocity and velocity_response

Examples

How to query and modify a collision object component’s angular velocity:

-- get angular velocity from collision object "collisionobject" in gameobject "boulder"
local velocity = go.get("boulder#collisionobject", "angular_velocity")
-- do something interesting
if velocity.z < 0 then
    -- clockwise rotation
    ...
else
    -- counter clockwise rotation
    ...
end
-- decrease it by 10%
velocity.z = velocity.z * 0.9
go.set("boulder#collisionobject", "angular_velocity", velocity * 0.9)

apply_force

Type: MESSAGE Post this message to a collision-object-component to apply the specified force on the collision object. The collision object must be dynamic.

Parameters

• force (vector3) - the force to be applied on the collision object, measured in Newton
• position (vector3) - the position where the force should be applied

Examples

Assuming the instance of the script has a collision-object-component with id “co”:

-- apply a force of 1 Newton towards world-x at the center of the game object instance
msg.post("#co", "apply_force", {force = vmath.vector3(1, 0, 0), position = go.get_world_position()})

collision_event

Type: MESSAGE See physics.set_event_listener. This message is sent to a function specified in physics.set_event_listener when two collision objects collide. This message only reports that a collision has occurred and will be sent once per frame and per colliding pair. For more detailed information, check for the contact_point_event.

Parameters

• a (table) - collision information for object A

position

vector3 The world position of object A</dd>

id

hash The ID of object A</dd>

group

hash The collision group of object A</dd> </dl>

• b (table) - collision information for object B

position

vector3 The world position of object B</dd>

id

hash The ID of object B</dd>

group

hash The collision group of object B</dd> </dl>

Examples

How to take action when a collision occurs:

physics.set_event_listener(function(self, event, data)
  if event == hash("collision_event") then
      pprint(data)
      -- {
      --  a = {
      --          group = hash: [default],
      --          position = vmath.vector3(183, 666, 0),
      --          id = hash: [/go1]
      --      },
      --  b = {
      --          group = hash: [default],
      --          position = vmath.vector3(185, 704.05865478516, 0),
      --          id = hash: [/go2]
      --      }
      -- }
  end
end)

collision_response

Type: MESSAGE This message is broadcasted to every component of an instance that has a collision object, when the collision object collides with another collision object. For a script to take action when such a collision happens, it should check for this message in its on_message callback function. This message only reports that a collision actually happened and will only be sent once per colliding pair and frame. To retrieve more detailed information, check for the contact_point_response instead.

Parameters

• other_id (hash) - the id of the instance the collision object collided with
• other_position (vector3) - the world position of the instance the collision object collided with
• other_group (hash) - the collision group of the other collision object
• own_group (hash) - the collision group of the own collision object

Examples

How to take action when a collision occurs:

function on_message(self, message_id, message, sender)
    -- check for the message
    if message_id == hash("collision_response") then
        -- take action
    end
end

contact_point_event

Type: MESSAGE See physics.set_event_listener. This message is sent to a function specified in physics.set_event_listener when a collision object has contact points with another collision object. Since multiple contact points can occur for two colliding objects, this event can be sent multiple times in the same frame for the same two colliding objects. To only be notified once when the collision occurs, check for the collision_event event instead.

Parameters

• applied_impulse (number) - the impulse the contact resulted in
• distance (number) - the penetration distance between the objects, which is always positive
• a (table) - contact point information for object A

position

vector3 The world position of object A</dd>

id

hash The ID of object A</dd>

group

hash The collision group of object A</dd>

relative_velocity

vector3 The relative velocity of the collision object A as observed from B object</dd>

mass

number The mass of the collision object A in kg</dd>

normal

vector3 normal in world space of the contact point, which points from B object towards A object</dd> </dl>

• b (table) - contact point information for object B

position

vector3 The world position of object B</dd>

id

hash The ID of object B</dd>

group

hash The collision group of object B</dd>

relative_velocity

vector3 The relative velocity of the collision object B as observed from A object</dd>

mass

number The mass of the collision object B in kg</dd>

normal

vector3 normal in world space of the contact point, which points from A object towards B object</dd> </dl>

Examples

How to take action when a contact point occurs:

physics.set_event_listener(function(self, events)
  for _,event in ipairs(events):
    if event['type'] == hash("contact_point_event") then
        pprint(event)
        -- {
        --  applied_impulse = 310.00769042969,
        --  distance = 0.0714111328125,
        --  a = {
        --      position = vmath.vector3(446, 371, 0),
        --      relative_velocity = vmath.vector3(1.1722083854693e-06, -20.667181015015, -0),
        --      mass = 0,
        --      group = hash: [default],
        --      id = hash: [/flat],
        --      normal = vmath.vector3(-0, -1, -0)
        --  },
        --  b = {
        --      position = vmath.vector3(185, 657.92858886719, 0),
        --      relative_velocity = vmath.vector3(-1.1722083854693e-06, 20.667181015015, 0),
        --      mass = 10,
        --      group = hash: [default],
        --      id = hash: [/go2],
        --      normal = vmath.vector3(0, 1, 0)
        --  },
        --  type = hash: [contact_point_event]
        -- }
     end
   end
end)

contact_point_response

Type: MESSAGE This message is broadcasted to every component of an instance that has a collision object, when the collision object has contact points with respect to another collision object. For a script to take action when such contact points occur, it should check for this message in its on_message callback function. Since multiple contact points can occur for two colliding objects, this message can be sent multiple times in the same frame for the same two colliding objects. To only be notified once when the collision occurs, check for the collision_response message instead.

Parameters

• position (vector3) - world position of the contact point
• normal (vector3) - normal in world space of the contact point, which points from the other object towards the current object
• relative_velocity (vector3) - the relative velocity of the collision object as observed from the other object
• distance (number) - the penetration distance between the objects, which is always positive
• applied_impulse (number) - the impulse the contact resulted in
• life_time (number) - life time of the contact, not currently used
• mass (number) - the mass of the current collision object in kg
• other_mass (number) - the mass of the other collision object in kg
• other_id (hash) - the id of the instance the collision object is in contact with
• other_position (vector3) - the world position of the other collision object
• other_group (hash) - the collision group of the other collision object
• own_group (hash) - the collision group of the own collision object

Examples

How to take action when a contact point occurs:

function on_message(self, message_id, message, sender)
    -- check for the message
    if message_id == hash("contact_point_response") then
        -- take action
    end
end

linear_damping

Type: PROPERTY The linear damping value for the collision object. Setting this value alters the damping of linear motion of the object. Valid values are between 0 (no damping) and 1 (full damping).

Examples

How to increase a collision object component’s linear damping:

-- get linear damping from collision object "collisionobject" in gameobject "floater"
local target = "floater#collisionobject"
local damping = go.get(target, "linear_damping")
-- increase it by 10% if it's below 0.9
if damping <= 0.9 then
    go.set(target, "linear_damping", damping * 1.1)
end

linear_velocity

Type: PROPERTY The current linear velocity of the collision object component as a vector3. The velocity is measured in units/s (pixels/s).

Replaces: request_velocity and velocity_response

Examples

How to query and modify a collision object component’s linear velocity:

-- get linear velocity from collision object "collisionobject" in gameobject "ship"
local source = "ship#collisionobject"
local velocity = go.get(source, "linear_velocity")
-- decrease it by 10%
go.set(source, "linear_velocity", velocity * 0.9)
-- apply the velocity on target game object "boulder"'s collision object as a force
local target = "boulder#collisionobject"
local pos = go.get_position(target)
msg.post(target, "apply_force", { force = velocity, position = pos })

mass

Type: PROPERTY READ ONLY Returns the defined physical mass of the collision object component as a number.

Examples

How to query a collision object component’s mass:

-- get mass from collision object component "boulder"
local mass = go.get("#boulder", "mass")
-- do something useful
assert(mass > 1)

physics.create_joint

Type: FUNCTION Create a physics joint between two collision object components. Note: Currently only supported in 2D physics.

Parameters

• joint_type (number) - the joint type

• collisionobject_a (string

  hash

  url) - first collision object

• joint_id (string

  hash) - id of the joint

• position_a (vector3) - local position where to attach the joint on the first collision object

• collisionobject_b (string

  hash

  url) - second collision object

• position_b (vector3) - local position where to attach the joint on the second collision object
• properties (table) (optional) - optional joint specific properties table See each joint type for possible properties field. The one field that is accepted for all joint types is:
• boolean collide_connected: Set this flag to true if the attached bodies should collide.

physics.destroy_joint

Type: FUNCTION Destroy an already physics joint. The joint has to be created before a destroy can be issued. Note: Currently only supported in 2D physics.

Parameters

• collisionobject (string

  hash

  url) - collision object where the joint exist

• joint_id (string

  hash) - id of the joint

physics.get_gravity

Type: FUNCTION Get the gravity in runtime. The gravity returned is not global, it will return the gravity for the collection that the function is called from. Note: For 2D physics the z component will always be zero.

Returns

• gravity (vector3) - gravity vector of collection

Examples

function init(self)
    local gravity = physics.get_gravity()
    -- Inverse gravity!
    gravity = -gravity
    physics.set_gravity(gravity)
end

physics.get_group

Type: FUNCTION Returns the group name of a collision object as a hash.

Parameters

• url (string

  hash

  url) - the collision object to return the group of.

Returns

• group (hash) - hash value of the group.

local function check_is_enemy()
    local group = physics.get_group("#collisionobject")
    return group == hash("enemy")
end

physics.get_joint_properties

Type: FUNCTION Get a table for properties for a connected joint. The joint has to be created before properties can be retrieved. Note: Currently only supported in 2D physics.

Parameters

• collisionobject (string

  hash

  url) - collision object where the joint exist

• joint_id (string

  hash) - id of the joint

Returns

• properties (table) - properties table. See the joint types for what fields are available, the only field available for all types is:

• boolean collide_connected: Set this flag to true if the attached bodies should collide.

physics.get_joint_reaction_force

Type: FUNCTION Get the reaction force for a joint. The joint has to be created before the reaction force can be calculated. Note: Currently only supported in 2D physics.

Parameters

• collisionobject (string

  hash

  url) - collision object where the joint exist

• joint_id (string

  hash) - id of the joint

Returns

• force (vector3) - reaction force for the joint

physics.get_joint_reaction_torque

Type: FUNCTION Get the reaction torque for a joint. The joint has to be created before the reaction torque can be calculated. Note: Currently only supported in 2D physics.

Parameters

• collisionobject (string

  hash

  url) - collision object where the joint exist

• joint_id (string

  hash) - id of the joint

Returns

• torque (number) - the reaction torque on bodyB in N*m.

physics.get_maskbit

Type: FUNCTION Returns true if the specified group is set in the mask of a collision object, false otherwise.

Parameters

• url (string

  hash

  url) - the collision object to check the mask of.

• group (string) - the name of the group to check for.

Returns

• maskbit (boolean) - boolean value of the maskbit. ‘true’ if present, ‘false’ otherwise.

local function is_invincible()
    -- check if the collisionobject would collide with the "bullet" group
    local invincible = physics.get_maskbit("#collisionobject", "bullet")
    return invincible
end

physics.get_shape

Type: FUNCTION Gets collision shape data from a collision object

Parameters

• url (string

  hash

  url) - the collision object.

• shape (string

  hash) - the name of the shape to get data for.

Returns

• table (table) - A table containing meta data about the physics shape

type

number The shape type. Supported values:</dd> </dl>

• physics.SHAPE_TYPE_SPHERE
• physics.SHAPE_TYPE_BOX
• physics.SHAPE_TYPE_CAPSULE Only supported for 3D physics
• physics.SHAPE_TYPE_HULL

The returned table contains different fields depending on which type the shape is. If the shape is a sphere:

diameter

number the diameter of the sphere shape</dd> </dl> If the shape is a box:

dimensions

vector3 a vmath.vector3 of the box dimensions</dd> </dl> If the shape is a capsule:

diameter

number the diameter of the capsule poles</dd>

height

number the height of the capsule</dd> </dl>

local function get_shape_meta()
    local sphere = physics.get_shape("#collisionobject", "my_sphere_shape")
    -- returns a table with sphere.diameter
    return sphere
end

physics.JOINT_TYPE_FIXED

Type: CONSTANT The following properties are available when connecting a joint of JOINT_TYPE_FIXED type:

Parameters

• max_length (number) - The maximum length of the rope.

physics.JOINT_TYPE_HINGE

Type: CONSTANT The following properties are available when connecting a joint of JOINT_TYPE_HINGE type:

Parameters

• reference_angle (number) - The bodyB angle minus bodyA angle in the reference state (radians).
• lower_angle (number) - The lower angle for the joint limit (radians).
• upper_angle (number) - The upper angle for the joint limit (radians).
• max_motor_torque (number) - The maximum motor torque used to achieve the desired motor speed. Usually in N-m.
• motor_speed (number) - The desired motor speed. Usually in radians per second.
• enable_limit (boolean) - A flag to enable joint limits.
• enable_motor (boolean) - A flag to enable the joint motor.
• joint_angle (number) - READ ONLYCurrent joint angle in radians. (Read only field, available from physics.get_joint_properties())
• joint_speed (number) - READ ONLYCurrent joint angle speed in radians per second. (Read only field, available from physics.get_joint_properties())

physics.JOINT_TYPE_SLIDER

Type: CONSTANT The following properties are available when connecting a joint of JOINT_TYPE_SLIDER type:

Parameters

• local_axis_a (vector3) - The local translation unit axis in bodyA.
• reference_angle (number) - The constrained angle between the bodies: bodyB_angle - bodyA_angle.
• enable_limit (boolean) - Enable/disable the joint limit.
• lower_translation (number) - The lower translation limit, usually in meters.
• upper_translation (number) - The upper translation limit, usually in meters.
• enable_motor (boolean) - Enable/disable the joint motor.
• max_motor_force (number) - The maximum motor torque, usually in N-m.
• motor_speed (number) - The desired motor speed in radians per second.
• joint_translation (number) - READ ONLYCurrent joint translation, usually in meters. (Read only field, available from physics.get_joint_properties())
• joint_speed (number) - READ ONLYCurrent joint translation speed, usually in meters per second. (Read only field, available from physics.get_joint_properties())

physics.JOINT_TYPE_SPRING

Type: CONSTANT The following properties are available when connecting a joint of JOINT_TYPE_SPRING type:

Parameters

• length (number) - The natural length between the anchor points.
• frequency (number) - The mass-spring-damper frequency in Hertz. A value of 0 disables softness.
• damping (number) - The damping ratio. 0 = no damping, 1 = critical damping.

physics.JOINT_TYPE_WELD

Type: CONSTANT The following properties are available when connecting a joint of JOINT_TYPE_WELD type:

Parameters

• reference_angle (number) - READ ONLYThe bodyB angle minus bodyA angle in the reference state (radians).
• frequency (number) - The mass-spring-damper frequency in Hertz. Rotation only. Disable softness with a value of 0.
• damping (number) - The damping ratio. 0 = no damping, 1 = critical damping.

physics.JOINT_TYPE_WHEEL

Type: CONSTANT The following properties are available when connecting a joint of JOINT_TYPE_WHEEL type:

Parameters

• local_axis_a (vector3) - The local translation unit axis in bodyA.
• max_motor_torque (number) - The maximum motor torque used to achieve the desired motor speed. Usually in N-m.
• motor_speed (number) - The desired motor speed in radians per second.
• enable_motor (boolean) - Enable/disable the joint motor.
• frequency (number) - The mass-spring-damper frequency in Hertz. Rotation only. Disable softness with a value of 0.
• damping (number) - The spring damping ratio. 0 = no damping, 1 = critical damping.
• joint_translation (number) - READ ONLYCurrent joint translation, usually in meters. (Read only field, available from physics.get_joint_properties())
• joint_speed (number) - READ ONLYCurrent joint translation speed, usually in meters per second. (Read only field, available from physics.get_joint_properties())

physics.raycast

Type: FUNCTION Ray casts are used to test for intersections against collision objects in the physics world. Collision objects of types kinematic, dynamic and static are tested against. Trigger objects do not intersect with ray casts. Which collision objects to hit is filtered by their collision groups and can be configured through groups. NOTE: Ray casts will ignore collision objects that contain the starting point of the ray. This is a limitation in Box2D.

Parameters

• from (vector3) - the world position of the start of the ray
• to (vector3) - the world position of the end of the ray
• groups (table) - a lua table containing the hashed groups for which to test collisions against
• options (table) (optional) - a lua table containing options for the raycast.

all

boolean Set to true to return all ray cast hits. If false, it will only return the closest hit.</dd> </dl>

Returns

• result (table

  nil) - It returns a list. If missed it returns nil. See ray_cast_response for details on the returned values.

Examples

How to perform a ray cast synchronously:

function init(self)
    self.groups = {hash("world"), hash("enemy")}
end

function update(self, dt)
    -- request ray cast
    local result = physics.raycast(from, to, self.groups, {all=true})
    if result ~= nil then
        -- act on the hit (see 'ray_cast_response')
        for _,result in ipairs(results) do
            handle_result(result)
        end
    end
end

physics.raycast_async

Type: FUNCTION Ray casts are used to test for intersections against collision objects in the physics world. Collision objects of types kinematic, dynamic and static are tested against. Trigger objects do not intersect with ray casts. Which collision objects to hit is filtered by their collision groups and can be configured through groups. The actual ray cast will be performed during the physics-update.

If an object is hit, the result will be reported via a ray_cast_response message. If there is no object hit, the result will be reported via a ray_cast_missed message.

NOTE: Ray casts will ignore collision objects that contain the starting point of the ray. This is a limitation in Box2D.

Parameters

• from (vector3) - the world position of the start of the ray
• to (vector3) - the world position of the end of the ray
• groups (table) - a lua table containing the hashed groups for which to test collisions against
• request_id (number) (optional) - a number in range [0,255]. It will be sent back in the response for identification, 0 by default

Examples

How to perform a ray cast asynchronously:

function init(self)
    self.my_groups = {hash("my_group1"), hash("my_group2")}
end

function update(self, dt)
    -- request ray cast
    physics.raycast_async(my_start, my_end, self.my_groups)
end

function on_message(self, message_id, message, sender)
    -- check for the response
    if message_id == hash("ray_cast_response") then
        -- act on the hit
    elseif message_id == hash("ray_cast_missed") then
        -- act on the miss
    end
end

physics.set_event_listener

Type: FUNCTION Only one physics world event listener can be set at a time.

Parameters

• callback (function(self, events)

  nil) - A callback that receives an information about all the physics interactions in this physics world.

self

object The calling script</dd>

event

constant The type of event. Can be one of these messages:</dd> </dl>

• contact_point_event
• collision_event
• trigger_event
• ray_cast_response
• ray_cast_missed

data

table The callback value data is a table that contains event-related data. See the documentation for details on the messages.</dd> </dl>

Examples

local function physics_world_listener(self, events)
  for _,event in ipairs(events):
      local event_type = event['type']
      if event_type == hash("contact_point_event") then
          pprint(event)
          -- {
          --  distance = 2.1490633487701,
          --  applied_impulse = 0
          --  a = { --[[0x113f7c6c0]]
          --    group = hash: [box],
          --    id = hash: [/box]
          --    mass = 0,
          --    normal = vmath.vector3(0.379, 0.925, -0),
          --    position = vmath.vector3(517.337, 235.068, 0),
          --    instance_position = vmath.vector3(480, 144, 0),
          --    relative_velocity = vmath.vector3(-0, -0, -0),
          --  },
          --  b = { --[[0x113f7c840]]
          --    group = hash: [circle],
          --    id = hash: [/circle]
          --    mass = 0,
          --    normal = vmath.vector3(-0.379, -0.925, 0),
          --    position = vmath.vector3(517.337, 235.068, 0),
          --    instance_position = vmath.vector3(-0.0021, 0, -0.0022),
          --    relative_velocity = vmath.vector3(0, 0, 0),
          --  },
          -- }
      elseif event == hash("collision_event") then
          pprint(event)
          -- {
          --  a = {
          --          group = hash: [default],
          --          position = vmath.vector3(183, 666, 0),
          --          id = hash: [/go1]
          --      },
          --  b = {
          --          group = hash: [default],
          --          position = vmath.vector3(185, 704.05865478516, 0),
          --          id = hash: [/go2]
          --      }
          -- }
      elseif event ==  hash("trigger_event") then
          pprint(event)
          -- {
          --  enter = true,
          --  b = {
          --      group = hash: [default],
          --      id = hash: [/go2]
          --  },
          --  a = {
          --      group = hash: [default],
          --      id = hash: [/go1]
          --  }
          -- },
      elseif event ==  hash("ray_cast_response") then
          pprint(event)
          --{
          --  group = hash: [default],
          --  request_id = 0,
          --  position = vmath.vector3(249.92222595215, 249.92222595215, 0),
          --  fraction = 0.68759721517563,
          --  normal = vmath.vector3(0, 1, 0),
          --  id = hash: [/go]
          -- }
      elseif event ==  hash("ray_cast_missed") then
          pprint(event)
          -- {
          --  request_id = 0
          --},
      end
end

function init(self)
    physics.set_event_listener(physics_world_listener)
end

physics.set_gravity

Type: FUNCTION Set the gravity in runtime. The gravity change is not global, it will only affect the collection that the function is called from. Note: For 2D physics the z component of the gravity vector will be ignored.

Parameters

• gravity (vector3) - the new gravity vector

Examples

function init(self)
    -- Set "upside down" gravity for this collection.
    physics.set_gravity(vmath.vector3(0, 10.0, 0))
end

physics.set_group

Type: FUNCTION Updates the group property of a collision object to the specified string value. The group name should exist i.e. have been used in a collision object in the editor.

Parameters

• url (string

  hash

  url) - the collision object affected.

• group (string) - the new group name to be assigned.

local function change_collision_group()
     physics.set_group("#collisionobject", "enemy")
end

physics.set_hflip

Type: FUNCTION Flips the collision shapes horizontally for a collision object

Parameters

• url (string

  hash

  url) - the collision object that should flip its shapes

• flip (boolean) - true if the collision object should flip its shapes, false if not

Examples

function init(self)
    self.fliph = true -- set on some condition
    physics.set_hflip("#collisionobject", self.fliph)
end

physics.set_joint_properties

Type: FUNCTION Updates the properties for an already connected joint. The joint has to be created before properties can be changed. Note: Currently only supported in 2D physics.

Parameters

• collisionobject (string

  hash

  url) - collision object where the joint exist

• joint_id (string

  hash) - id of the joint

• properties (table) - joint specific properties table Note: The collide_connected field cannot be updated/changed after a connection has been made.

physics.set_maskbit

Type: FUNCTION Sets or clears the masking of a group (maskbit) in a collision object.

Parameters

• url (string

  hash

  url) - the collision object to change the mask of.

• group (string) - the name of the group (maskbit) to modify in the mask.
• maskbit (boolean) - boolean value of the new maskbit. ‘true’ to enable, ‘false’ to disable.

local function make_invincible()
    -- no longer collide with the "bullet" group
    physics.set_maskbit("#collisionobject", "bullet", false)
end

physics.set_shape

Type: FUNCTION Sets collision shape data for a collision object. Please note that updating data in 3D can be quite costly for box and capsules. Because of the physics engine, the cost comes from having to recreate the shape objects when certain shapes needs to be updated.

Parameters

• url (string

  hash

  url) - the collision object.

• shape (string

  hash) - the name of the shape to get data for.

• table (table) - the shape data to update the shape with. See physics.get_shape for a detailed description of each field in the data table.

local function set_shape_data()
    -- set capsule shape data
    local data = {}
    data.type = physics.SHAPE_TYPE_CAPSULE
    data.diameter = 10
    data.height = 20
    physics.set_shape("#collisionobject", "my_capsule_shape", data)

    -- set sphere shape data
    data = {}
    data.type = physics.SHAPE_TYPE_SPHERE
    data.diameter = 10
    physics.set_shape("#collisionobject", "my_sphere_shape", data)

    -- set box shape data
    data = {}
    data.type = physics.SHAPE_TYPE_BOX
    data.dimensions = vmath.vector3(10, 10, 5)
    physics.set_shape("#collisionobject", "my_box_shape", data)
end

physics.set_vflip

Type: FUNCTION Flips the collision shapes vertically for a collision object

Parameters

• url (string

  hash

  url) - the collision object that should flip its shapes

• flip (boolean) - true if the collision object should flip its shapes, false if not

Examples

function init(self)
    self.flipv = true -- set on some condition
    physics.set_vflip("#collisionobject", self.flipv)
end

physics.SHAPE_TYPE_BOX

Type: CONSTANT

physics.SHAPE_TYPE_CAPSULE

Type: CONSTANT

physics.SHAPE_TYPE_HULL

Type: CONSTANT

physics.SHAPE_TYPE_SPHERE

Type: CONSTANT

physics.update_mass

Type: FUNCTION The function recalculates the density of each shape based on the total area of all shapes and the specified mass, then updates the mass of the body accordingly. Note: Currently only supported in 2D physics.

Parameters

• collisionobject (string

  hash

  url) - the collision object whose mass needs to be updated.

• mass (number) - the new mass value to set for the collision object.

Examples

 physics.update_mass("#collisionobject", 14)

physics.wakeup

Type: FUNCTION Collision objects tend to fall asleep when inactive for a small period of time for efficiency reasons. This function wakes them up.

Parameters

• url (string

  hash

  url) - the collision object to wake.

function on_input(self, action_id, action)
    if action_id == hash("test") and action.pressed then
        physics.wakeup("#collisionobject")
    end
end

ray_cast_missed

Type: MESSAGE This message is sent back to the sender of a ray_cast_request, or to the physics world listener if it is set (see physics.set_event_listener), if the ray didn’t hit any collision object. See physics.raycast_async for examples of how to use it.

Parameters

• request_id (number) - id supplied when the ray cast was requested

ray_cast_response

Type: MESSAGE This message is sent back to the sender of a ray_cast_request, or to the physics world listener if it is set (see physics.set_event_listener), if the ray hits a collision object. See physics.raycast_async for examples of how to use it.

Parameters

• fraction (number) - the fraction of the hit measured along the ray, where 0 is the start of the ray and 1 is the end
• position (vector3) - the world position of the hit
• normal (vector3) - the normal of the surface of the collision object where it was hit
• id (hash) - the instance id of the hit collision object
• group (hash) - the collision group of the hit collision object as a hashed name
• request_id (number) - id supplied when the ray cast was requested

trigger_event

Type: MESSAGE See physics.set_event_listener. This message is sent to a function specified in physics.set_event_listener when a collision object interacts with another collision object and one of them is a trigger. This message only reports that an interaction actually happened and will be sent once per colliding pair and frame. For more detailed information, check for the contact_point_event.

Parameters

• enter (boolean) - if the interaction was an entry or not
• a (table) - <dl>

interaction information for object A

id

hash The ID of object A</dd>

group

hash The collision group of object A</dd> </dl>

• b (table) - collision information for object B

id

hash The ID of object B</dd>

group

hash The collision group of object B</dd> </dl>

Examples

How to take action when a trigger interaction occurs:

physics.set_event_listener(function(self, event, data)
 if event ==  hash("trigger_event") then
     if data.enter then
        -- take action for entry
     else
        -- take action for exit
     end
     pprint(data)
     -- {
     --  enter = true,
     --  b = {
     --      group = hash: [default],
     --      id = hash: [/go2]
     --  },
     --  a = {
     --      group = hash: [default],
     --      id = hash: [/go1]
     --  }
     -- },
  end
end)

trigger_response

Type: MESSAGE This message is broadcasted to every component of an instance that has a collision object, when the collision object interacts with another collision object and one of them is a trigger. For a script to take action when such an interaction happens, it should check for this message in its on_message callback function. This message only reports that an interaction actually happened and will only be sent once per colliding pair and frame. To retrieve more detailed information, check for the contact_point_response instead.

Parameters

• other_id (hash) - the id of the instance the collision object collided with
• enter (boolean) - if the interaction was an entry or not
• other_group (hash) - the collision group of the triggering collision object
• own_group (hash) - the collision group of the own collision object

Examples

How to take action when a trigger interaction occurs:

function on_message(self, message_id, message, sender)
    -- check for the message
    if message_id == hash("trigger_response") then
        if message.enter then
            -- take action for entry
        else
            -- take action for exit
        end
    end
end