Version: beta
FUNCTION | |
---|---|
physics.raycast_async() | requests a ray cast to be performed |
physics.raycast() | requests a ray cast to be performed |
physics.create_joint() | create a physics joint |
physics.destroy_joint() | destroy a physics joint |
physics.get_joint_properties() | get properties for a joint |
physics.set_joint_properties() | set properties for a joint |
physics.get_joint_reaction_force() | get the reaction force for a joint |
physics.get_joint_reaction_torque() | get the reaction torque for a joint |
physics.set_gravity() | set the gravity for collection |
physics.get_gravity() | get the gravity for collection |
physics.set_hflip() | flip the geometry horizontally for a collision object |
physics.set_vflip() | flip the geometry vertically for a collision object |
physics.wakeup() | explicitly wakeup a collision object |
physics.set_group() | change the group of a collision object |
physics.get_group() | returns the group of a collision object |
physics.set_maskbit() | updates the mask of a collision object |
physics.get_maskbit() | checks the presense of a group in the mask (maskbit) of a collision object |
CONSTANT | |
---|---|
physics.JOINT_TYPE_SPRING | spring joint type |
physics.JOINT_TYPE_FIXED | fixed joint type |
physics.JOINT_TYPE_HINGE | hinge joint type |
physics.JOINT_TYPE_SLIDER | slider joint type |
physics.JOINT_TYPE_WELD | weld joint type |
MESSAGE | |
---|---|
apply_force | applies a force on a collision object |
collision_response | reports a collision between two collision objects |
contact_point_response | reports a contact point between two collision objects |
trigger_response | reports interaction (enter/exit) between a trigger collision object and another collision object |
ray_cast_response | reports a ray cast hit |
ray_cast_missed | reports a ray cast miss |
PROPERTIES | |
---|---|
mass | number collision object mass |
linear_velocity | vector3 collision object linear velocity |
angular_velocity | vector3 collision object angular velocity |
linear_damping | number collision object linear damping |
angular_damping | number collision object angular damping |
physics.raycast_async(from,to,groups,[request_id])
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.
ray_cast_response
message.ray_cast_missed
message.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 |
a number between [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.raycast(from,to,groups,options)
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
.
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 |
a lua table containing options for the raycast.
|
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.create_joint(joint_type,collisionobject_a,joint_id,position_a,collisionobject_b,position_b,[properties])
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 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(collisionobject,joint_id)
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_joint_properties(collisionobject,joint_id)
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:
|
physics.set_joint_properties(collisionobject,joint_id,properties)
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.get_joint_reaction_force(collisionobject,joint_id)
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(collisionobject,joint_id)
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 |
float | the reaction torque on bodyB in N*m. |
physics.set_gravity(gravity)
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.get_gravity()
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.
PARAMETERS
None
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.set_hflip(url,flip)
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_vflip(url,flip)
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.wakeup(url)
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.
|
physics.set_group(url,group)
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.
|
physics.get_group(url)
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.
|
physics.set_maskbit(url,group,maskbit)
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.
|
physics.get_maskbit(url,group)
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.
|
The following properties are available when connecting a joint of JOINT_TYPE_SPRING
type:
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. |
The following properties are available when connecting a joint of JOINT_TYPE_FIXED
type:
max_length |
number |
The maximum length of the rope. |
The following properties are available when connecting a joint of JOINT_TYPE_HINGE
type:
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() ) |
The following properties are available when connecting a joint of JOINT_TYPE_SLIDER
type:
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() ) |
The following properties are available when connecting a joint of JOINT_TYPE_WELD
type:
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. |
Post this message to a collision-object-component to apply the specified force on the collision object. The collision object must be dynamic.
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()})
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.
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 (hash) |
own_group |
hash |
the collision group of the own collision object (hash) |
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
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.
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 (hash) |
own_group |
hash |
the collision group of the own collision object (hash) |
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
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.
other_id |
hash |
the id of the instance the collision object collided with (hash) |
enter |
boolean |
if the interaction was an entry or not |
other_group |
hash |
the collision group of the triggering collision object (hash) |
own_group |
hash |
the collision group of the own collision object (hash) |
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
This message is sent back to the sender of a ray_cast_request
, if the ray hit a
collision object. See physics.raycast_async
for examples of how to use it.
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 |
This message is sent back to the sender of a ray_cast_request
, if the ray didn't hit any
collision object. See physics.raycast_async
for examples of how to use it.
request_id |
number |
id supplied when the ray cast was requested |
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)
The current linear velocity of the collision object component as a vector3. The velocity is measured in units/s (pixels/s).
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 })
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.
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)
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
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)