Unigine.Physics Class
Controls the simulation of physics. For more information on principles and implementation of physics in real-time rendering, see the articles Execution Sequence, Physics and Simulation of Physics.
Physics Class
Members
void setAngularDamping(float damping)
Updates the current angular damping value.Arguments
- float damping - New angular damping. If a negative value is provided, 0 will be used instead.
float getAngularDamping()
Returns the current angular damping value.Return value
Angular damping.Body getBody(int id)
Returns a body with a given ID.Arguments
- int id - Body ID.
Return value
Body with a given ID or NULL (0), if there is no body with a given ID.int isBody(int id)
Checks if a body with a given ID exists.Arguments
- int id - Body ID.
Return value
1 if a body with a given ID exists; otherwise, 0.float getBroadTime()
Returns the duration of the broad phase, during which potentially colliding objects are found.Return value
The broad phase duration value, milliseconds.void setBudget(float budget)
Sets the physics simulation budget. Physics isn't simulated when time is out of the budget.Arguments
- float budget - The budget value in seconds. The default value is 1/20.
float getBudget()
Returns the physics simulation budget. Physics isn't simulated when time is out of the budget.Return value
The budget value in seconds. The default value is 1/20.void setData(string data)
Sets user data associated with the world. In the *.world file, the data is set in the data tag.Arguments
- string data - User data. Data can contain an XML formatted string.
string getData()
Returns user string data associated with the world. This string is written directly into the data tag of the *.world file.Return value
User string data.void setDistance(float distance)
Updates a distance after which the physics will not be simulated.Arguments
- float distance - Distance in units.
float getDistance()
Returns a distance after which the physics will not be simulated.Return value
Distance in units.void setEnabled(int enable)
Enables or disables physics simulation.Arguments
- int enable - Positive number to enable physics, 0 to disable it.
int isEnabled()
Returns a value indicating if physics simulation is enabled. The default is 1.Return value
1 if physics is enabled; otherwise, 0.void setFixed(int fixed)
Sets a flag to synchronize rendering FPS to physics one. Such FPS limitation allows to calculate physics each rendered frame (rather then interpolate it when this flag is set to 0). In this mode, there are no twitching of physical objects if they have non-linear velocities. If the rendering FPS is lower than the physics one, this flag has no effect.Arguments
- int fixed - 1 to cap rendering FPS to physics one; 0 to interpolate physics if rendering FPS is higher.
int isFixed()
Returns a flag indicating if rendering FPS is synchronized to physics one. Such FPS limitation allows to calculate physics each rendered frame (rather then interpolate it when this flag is set to 0). In this mode, there are no twitching of physical objects if they have non-linear velocities. If the rendering FPS is lower than the physics one, this flag has no effect.Return value
Returns 1 if the rendering FPS is synchronized to physics one; 0 if the physics is interpolated if rendering FPS is higher.int getFrame()
Returns the current frame of physics update.Return value
Frame number.void setFrozenAngularVelocity(float velocity)
Updates the angular velocity threshold for freezing object simulation. If the object angular velocity remains lower than this threshold during the number of Frozen frames (together with linear one), it stops to be updated.Arguments
- float velocity - New "freeze" angular velocity. If a negative value is provided, 0 will be used instead.
float getFrozenAngularVelocity()
Returns the current angular velocity threshold for freezing object simulation. An object stops to be updated if its angular velocity remains lower than this threshold during the number of Frozen frames (together with linear one).Return value
"Freeze" angular velocity.void setFrozenLinearVelocity(float velocity)
Updates the linear velocity threshold for freezing object simulation. If the object linear velocity remains lower than this threshold during the number of Frozen frames (together with angular one), it stops to be updated.Arguments
- float velocity - New "freeze" linear velocity. If a negative value is provided, 0 will be used instead.
float getFrozenLinearVelocity()
Returns the current linear velocity threshold for freezing object simulation. An object stops to be updated if its linear velocity remains lower than this threshold during the number of Frozen frames (together with angular one).Return value
"Freeze" linear velocity.void setGravity(vec3 gravity)
Updates the current gravity value.Arguments
- vec3 gravity - New gravity.
vec3 getGravity()
Returns the current gravity value.Return value
Gravity.void setIFps(float ifps)
Updates a frame duration. In fact, this function updates the FPS count used to calculate physics.Arguments
- float ifps - Frame duration (1/FPS).
float getIFps()
Returns a physics frame duration.Return value
Frame duration (1 / FPS).float getIntegrateTime()
Returns the duration of the integrate phase, in which physics simulation results are applied to bodies.Return value
An integrate phase duration value, milliseconds.Object getIntersection(Vec3 p0, Vec3 p1, int mask, Node[] exclude, PhysicsIntersection intersection)
Performs tracing from the p0 point to the p1 point to find a collision object located on that line. If an object is assigned a body, intersection occurs with its shape. If an object has no body, this function detects intersection with surfaces (polygons) of objects with intersection flag set. Intersection is found only for objects with a matching mask if their ID is not found in the exclude list. Intersection is Intersection does not work for disabled objects.
Notice
This function uses world space coordinates.
Arguments
- Vec3 p0 - Line start point coordinates.
- Vec3 p1 - Line end point coordinates.
- int mask - Intersection mask. If 0 is passed, the function will return NULL.
- Node[] exclude - Array of nodes to be excluded.
- PhysicsIntersection intersection - PhysicsIntersection class instance containing intersection data.
Return value
The first intersected object, if found; otherwise, 0.Object getIntersection(Vec3 p0, Vec3 p1, int mask, PhysicsIntersection intersection)
Performs tracing from the p0 point to the p1 point to find a collision object located on that line. If an object is assigned a body, intersection occurs with its shape. If an object has no body, this function detects intersection with surfaces (polygons) of objects with intersection flag set. Intersection is found only for objects with a matching mask. Intersection does not work for disabled objects.
Notice
This function uses world space coordinates.
Usage Example
The following example shows how you can get the intersection information by using the PhysicsIntersection class. In this example we specify a line from the point of the camera (vec3 p0) to the point of the mouse pointer (vec3 p1). The executing sequence is the following:
- Define and initialize two points (p0 and p1) by using the Player.getDirectionFromScreen() function.
- Create an instance of the PhysicsIntersection class to get the intersection information.
- Check, if there is an intersection with an object with a shape or a collision object. The getIntersection() function returns an intersected object when the object intersects with the traced line.
- In this example, when the object intersects with the traced line, all the surfaces of the intersected object change their material parameters. If the object has a shape, its information will be shown in console. The PhysicsIntersection class instance gets the coordinates of the intersection point and the Shape class object. You can get all these fields by using getShape(), getPoint() functions.
Source code (C#)
public override int update() {
// initialize points of the mouse direction
Vec3 p0, p1;
// get the current player (camera)
Player player = Game.get().getPlayer();
if (player == null)
return 0;
// get width and height of the current application window
int width = App.get().getWidth();
int height = App.get().getHeight();
// get the current X and Y coordinates of the mouse pointer
int mouse_x = App.get().getMouseX();
int mouse_y = App.get().getMouseY();
// get the mouse direction from the player's position (p0) to the mouse cursor pointer (p1)
player.getDirectionFromScreen(out p0, out p1, mouse_x, mouse_y, width, height);
// create the instance of the PhysicsIntersection object to save the information about the intersection
PhysicsIntersection intersection = new PhysicsIntersection();
// get an intersection
Unigine.Object obj = Physics.get().getIntersection(p0, p1, 1, intersection);
// if the intersection has been occurred, change the parameter of the object's material
if (obj != null)
{
for (int i = 0; i < obj.getNumSurfaces(); i++)
{
obj.setMaterialParameter("albedo_color", new vec4(1.0f, 1.0f, 0.0f, 1.0f), i);
}
// if the intersected object has a shape, show the information about the intersection
Shape shape = intersection.getShape();
if (shape != null)
{
Log.message("physics intersection info: point: {0} shape: {1}\n", intersection.getPoint().GetType(), shape.getType().GetType());
}
}
return 1;
}Arguments
- Vec3 p0 - Line start point coordinates.
- Vec3 p1 - Line end point coordinates.
- int mask - Intersection mask. If 0 is passed, the function will return NULL.
- PhysicsIntersection intersection - PhysicsIntersection class instance containing intersection data.
Return value
The first intersected object, if found; otherwise, 0.Object getIntersection(Vec3 p0, Vec3 p1, int mask, PhysicsIntersectionNormal intersection)
Performs tracing from the p0 point to the p1 point to find a collision object located on that line. If an object is assigned a body, intersection occurs with its shape. If an object has no body, this function detects intersection with surfaces (polygons) of objects with intersection flag set. Intersection is found only for objects with a matching mask. Intersection does not work for disabled objects.
Notice
This function uses world space coordinates.
Arguments
- Vec3 p0 - Line start point coordinates.
- Vec3 p1 - Line end point coordinates.
- int mask - Intersection mask. If 0 is passed, the function will return NULL.
- PhysicsIntersectionNormal intersection - PhysicsIntersectionNormal class instance containing intersection data.
Return value
The first intersected object, if found; otherwise, 0.Object getIntersection(Vec3 p0, Vec3 p1, int mask, Node[] exclude, PhysicsIntersectionNormal intersection)
Performs tracing from the p0 point to the p1 point to find a collision object located on that line. If an object is assigned a body, intersection occurs with its shape. If an object has no body, this function detects intersection with surfaces (polygons) of objects with intersection flag set. Intersection is found only for objects with a matching mask if their ID is not found in the exclude list. Intersection is Intersection does not work for disabled objects.
Notice
This function uses world space coordinates.
Arguments
- Vec3 p0 - Line start point coordinates.
- Vec3 p1 - Line end point coordinates.
- int mask - Intersection mask. If 0 is passed, the function will return NULL.
- Node[] exclude - Array of nodes to be excluded.
- PhysicsIntersectionNormal intersection - PhysicsIntersectionNormal class instance containing intersection data.
Return value
The first intersected object, if found; otherwise, 0.Joint getJoint(int id)
Returns a joint with a given ID.Arguments
- int id - Joint ID.
Return value
Joint with a given ID or NULL (0), if there is no joint with a given ID.int isJoint(int id)
Checks if a joint with a given ID exists.Arguments
- int id - Joint ID.
Return value
1 if a joint with a given ID exists; otherwise, 0.void setLinearDamping(float damping)
Updates the current linear damping value.Arguments
- float damping - New linear damping. If a negative value is provided, 0 will be used instead.
float getLinearDamping()
Returns the current linear damping value.Return value
Linear damping.void setMaxAngularVelocity(float velocity)
Updates the maximum possible angular velocity.Arguments
- float velocity - New maximum velocity value. If a negative value is provided, 0 will be used instead.
float getMaxAngularVelocity()
Returns the current maximum possible angular velocity.Return value
Maximum possible angular velocity.void setMaxLinearVelocity(float velocity)
Updates the maximum possible linear velocity.Arguments
- float velocity - New maximum velocity value. If a negative value is provided, 0 will be used instead.
float getMaxLinearVelocity()
Returns the current maximum possible linear velocity.Return value
Maximum possible linear velocity.float getNarrowTime()
Returns the duration of the narrow phase, during which exact collision tests are performed.Return value
The narrow phase duration value, milliseconds.int getNumBodies()
Returns the number of bodies present within the physics radius.Return value
The number of bodies.int getNumContacts()
Returns the number of contacts within the physics radius; it includes contacts between the bodies (their shapes) and body-mesh contacts.Return value
The number of contacts.void setNumFrozenFrames(int frames)
Updates the number of frames, during which an object should keep certain angular and linear velocities to become frozen.Arguments
- int frames - Number of frames. If a non-positive value is provided, 1 will be used instead.
int getNumFrozenFrames()
Returns the current number of frames, during which an object should keep certain angular and linear velocities to become frozen.Return value
Number of frames.int getNumIslands()
Returns the number of physical islands within the physics radius that could be calculated separately. The lower this number, the less efficient multi-threading is, if enabled.Return value
The number of physical islands.void setNumIterations(int iterations)
Updates the number of iterations used to solve contacts and constraints. Note that if this value is too low, the precision of calculations will suffer.Arguments
- int iterations - New number of iterations. If a non-positive value is provided, 1 will be used instead.
int getNumIterations()
Returns the current number of iterations used to solve contacts and constraints.Return value
Current number of iterations.int getNumJoints()
Returns the number of joints within the physics radius.Return value
The number of joints.void setPenetrationFactor(float factor)
Updates the current penalty force factor.Arguments
- float factor - New penetration factor. 0 means no penalty force in contacts. The provided value is saturated in the range [0; 1].
float getPenetrationFactor()
Returns a penalty force factor. 0 means no penalty force in contacts. The maximum value is 1.Return value
Current penetration factor.void setPenetrationTolerance(float tolerance)
Updates the current penetration tolerance.Arguments
- float tolerance - New penetration tolerance. If a negative value is provided, 0 will be used instead, however, this value should be greater than 0 for stable simulation.
float getPenetrationTolerance()
Returns a value indicating how deeply one object can penetrate another.Return value
Current penetration tolerance.float getResponseTime()
Returns the duration value of the response phase, in which collision response is calculated and joints are solved.Return value
A response phase duration value, milliseconds.void setScale(float scale)
Updates a value that is used to scale a frame duration. The provided value is saturated in the range [0;16].Arguments
- float scale - Scaling factor.
float getScale()
Returns a value used to scale a frame duration.Return value
Value to scale the frame duration.Shape getShape(int id)
Returns a shape with a given ID.Arguments
- int id - Shape ID.
Return value
Shape with a given ID or NULL (0), if there is no shape with a given ID.int isShape(int id)
Checks if a shape with a given ID existsArguments
- int id - Shape ID.
Return value
1 if a shape with a given ID exists; otherwise, 0.float getSimulationTime()
Returns the duration of all of the simulation phases added together.Return value
A simulation phases duration value, milliseconds.void setStable(int stable)
Sets a value indicating if objects are updated in a definite order or not.Arguments
- int stable - 1 to indicate that the objects are updated in a definite order; 0 to indicate that an objects update order may change.
int isStable()
Returns a value indicating if objects are updated in a definite order or not. The default is 0 (the update order may change).Return value
Returns 1 if the objects are updated in a definite order; otherwise 0.void setTime(float time)
Forces simulation of physics for a given time. It means, until the set time elapses, physics will be calculated each physics tick (frame) that occurs depending on physics frame rate. It allows you to control the starting point for physics simulation.Source code (C#)
In the example, ifps is the time between frames of the renderer.
// AppWorldLogic.cs
/* ... */
public override int init() {
// to prevent physics from being automatically calculated with each update, set one of the following:
Physics.get().setEnabled(0)
// or
Physics.get().setScale(0)
}
public override int update() {
// add the time elapsed from the last physics update to the next time count cycle:
Physics.get().setTime(Physics.get().getTime()+ifps));
}
/* ... */Arguments
- float time - Time to continue updating physics in seconds.
float getTime()
Returns the current time that can be used when shifting between physics update frames.Return value
Time in seconds.float getTotalTime()
Returns the total time that both rendering and calculating of the frame took (the duration of the main loop in the application execution sequence).Return value
The total time value, milliseconds.float getUpdateTime()
Returns the duration of the update phase, during which the objects are prepared for their collision response to be calculated.Return value
The update phase duration value, milliseconds.void addUpdateNode(Node node)
Adds the node for which physical state should be updated. If a node is not added with this function, it won't be updated when out of physics simulation distance.Arguments
- Node node - Node to be updated.
void addUpdateNodes(Node[] nodes)
Adds the nodes for which physical state should be updated. If nodes are not added with this function, they won't be updated when out of physics simulation distance.Arguments
- Node[] nodes - Nodes to be updated.
int loadSettings(string name)
Loads the physics settings from a given file.Arguments
- string name - Path to an XML file with desired settings.
Return value
Returns 1 if the settings are loaded successfully; otherwise, 0.int loadWorld(Xml xml)
Loads physics settings from the Xml.Arguments
- Xml xml - Xml node.
Return value
Returns 1 if settings are loaded successfully; otherwise, 0.int removeScene(int id)
Removes the previously saved physics scene.Arguments
- int id - ID number of the scene.
Return value
Returns 1 if the scene is removed successfully; otherwise, 0.int restoreScene(int id)
Restores the previously saved physics scene from the buffer.Arguments
- int id - ID number of the scene.
Return value
Returns 1 if the scene is restored successfully; otherwise, 0.int restoreState(Stream stream)
Restores physics settings from the stream.Warning
This function is deprecated and will be removed in the next release.
Arguments
- Stream stream - Stream to restore settings from.
Return value
Returns 1 if settings are restored successfully; otherwise, 0.int saveScene()
Saves the current physics scene (physical properties of all objects) into the buffer.Return value
Scene buffer ID.int saveSettings(string name, int force = 0)
Saves the current physics settings to a given file.Arguments
- string name - Path to a target file.
- int force - Forced saving of physics settings.
Return value
Returns 1 if the settings are saved successfully; otherwise, 0.int saveState(Stream stream)
Saves physics settings into the stream.Warning
This function is deprecated and will be removed in the next release.
Arguments
- Stream stream - Stream to save settings into.
Return value
Returns 1 if settings are saved successfully; otherwise, 0.int saveWorld(Xml xml, int force = 0)
Saves physics settings into the Xml.Arguments
- Xml xml - Xml node.
- int force - Forced saving of physics settings.
Return value
Returns 1 if settings are saved successfully; otherwise, 0.Last update: 2018-08-10
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