Unigine::Physics Class

Header:

#include <UniginePhysics.h>

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.

Methods:

Name	Description View: Sort by:
setAngularDamping	Updates the current angular damping value.
getAngularDamping	Returns the current angular damping value.
setBudget	Sets the physics simulation budget.
getBudget	Returns the physics simulation budget.
setData	Sets user data associated with the world.
getData	Returns user string data associated with the world.
setDistance	Updates a distance after which the physics will not be simulated.
getDistance	Returns a distance after which the physics will not be simulated.
setEnabled	Enables or disables physics simulation.
isEnabled	Returns a value indicating if physics simulation is enabled.
setSyncEngineUpdateWithPhysics	Sets a flag to synchronize the Engine FPS to physics one.
isSyncEngineUpdateWithPhysics	Returns a flag indicating if the Engine FPS is synchronized to physics one.
getFrame	Returns the current frame of physics update.
setFrozenAngularVelocity	Updates the angular velocity threshold for freezing object simulation.
getFrozenAngularVelocity	Returns the current angular velocity threshold for freezing object simulation.
setFrozenLinearVelocity	Updates the linear velocity threshold for freezing object simulation.
getFrozenLinearVelocity	Returns the current linear velocity threshold for freezing object simulation.
setGravity	Updates the current gravity value.
getGravity	Returns the current gravity value.
setIFps	Updates a frame duration.
getIFps	Returns a physics frame duration.
getIntegrateTime	Returns the duration of the integrate phase, in which physics simulation results are applied to bodies.
setLinearDamping	Updates the current linear damping value.
getLinearDamping	Returns the current linear damping value.
setMaxAngularVelocity	Updates the maximum possible angular velocity.
getMaxAngularVelocity	Returns the current maximum possible angular velocity.
setMaxLinearVelocity	Updates the maximum possible linear velocity.
getMaxLinearVelocity	Returns the current maximum possible linear velocity.
getCollisionTime	Returns the duration of the collision detection phase, during which collisions between objects are found.
getNumBodies	Returns the number of bodies present within the physics radius.
getNumContacts	Returns the number of contacts within the physics radius; it includes contacts between the bodies (their shapes) and body-mesh contacts.
setNumFrozenFrames	Updates the number of frames, during which an object should keep certain angular and linear velocities to become frozen.
getNumFrozenFrames	Returns the current number of frames, during which an object should keep certain angular and linear velocities to become frozen.
getNumIslands	Returns the number of physical islands within the physics radius that could be calculated separately.
setNumIterations	Updates the number of iterations used to solve contacts and constraints.
getNumIterations	Returns the current number of iterations used to solve contacts and constraints.
getNumJoints	Returns the number of joints within the physics radius.
setPenetrationFactor	Updates the current penalty force factor.
getPenetrationFactor	Returns a penalty force factor.
setPenetrationTolerance	Updates the current penetration tolerance.
getPenetrationTolerance	Returns a value indicating how deeply one object can penetrate another.
getResponseTime	Returns the duration value of the response phase, in which collision response is calculated and joints are solved.
setScale	Updates a value that is used to scale a frame duration.
getScale	Returns a value used to scale a frame duration.
getSimulationTime	Returns the duration of all of the simulation phases added together.
setDeterministic	Sets a value indicating if objects are updated in a definite order or not.
isDeterministic	Returns a value indicating if objects are updated in a definite order or not.
setCurrentSubframeTime	Forces simulation of physics for a given time.
getCurrentSubframeTime	Returns the current time that can be used when shifting between physics update frames.
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).
setStableFPS	Returns a value indicating if frame time stabilization is enabled.
isStableFPS	Returns a value indicating if frame time stabilization is enabled.
setUpdateMode	Sets the update mode to be used for physics.
getUpdateMode	Returns the current physics update mode.
setMissedFrameLifetime	Sets the lifetime for missed frames.
getMissedFrameLifetime	Sets the lifetime for missed frames.
getBody	Returns a body with a given ID.
isBody	Checks if a body with a given ID exists.
getIntersection	Performs tracing from the p0 point to the p1 point to find a collision object located on that line.
getJoint	Returns a joint with a given ID.
isJoint	Checks if a joint with a given ID exists.
getShape	Returns a shape with a given ID.
isShape	Checks if a shape with a given ID exists.
addUpdateNode	Adds the node for which physical state should be updated.
addUpdateNodes	Adds the nodes for which physical state should be updated.
loadSettings	Loads the physics settings from a given file.
loadWorld	Loads physics settings from the Xml.
saveScene	Saves the current physics scene (physical properties of all objects) into the buffer.
restoreScene	Restores the previously saved physics scene from the buffer.
removeScene	Removes the previously saved physics scene.
saveState	Saves physics settings into the stream.
restoreState	Restores physics settings from the stream.
saveSettings	Saves the current physics settings to a given file.
saveWorld	Saves physics settings to the given Xml node.

Physics Class

Enums

UPDATE_MODE#

Physics update mode.

Name	Description
UPDATE_MODE_BEFORE_RENDERING = 0	Update Before Rendering. Physics update (along with the spatial tree update and user callbacks) is executed in the Main thread just before rendering is performed (render). The number of physics ticks executed before the rendering frame here is defined by the physics and the Engine framerates. This mode is the most clear and straightforward (everything is executed safely in a strictly determined order) with no frame lag (results of physics calculations are applied in the current frame). But, on the other hand, this mode is the slowest as there are no asynchronous parallel calculations (everything's in the Main thread). Use this mode in case the time lag is unacceptabe for your application (you need all physics calculations to be applied in the current frame) and you want maximum simplicity and strictly determined order of execution for user code (physicsUpdate and physics callbacks).
UPDATE_MODE_ASYNC_RENDERING = 1	Asynchronous update mode. Physics update is performed asynchronously to rendering. In case of several physics ticks per one rendering frame (when the Engine framerate is lower, or catching up is performed), only the first one is executed in parallel, then the physics module waits for the completion of the rendering process, returns to the Main thread and executes the rest of the physics ticks. There is a frame lag (results of physics calculations are applied in the next frame) and there is some ambiguity regarding the time, when user code (physicsUpdate and physics callbacks) is to be executed in case of several physics ticks per one rendering frame (some part is executed before rendering while the other just after it). This mode is the fastest one and is used by default.

Name

Description

UPDATE_MODE_BEFORE_RENDERING = 0

Update Before Rendering. Physics update (along with the spatial tree update and user callbacks) is executed in the Main thread just before rendering is performed (render). The number of physics ticks executed before the rendering frame here is defined by the physics and the Engine framerates. This mode is the most clear and straightforward (everything is executed safely in a strictly determined order) with no frame lag (results of physics calculations are applied in the current frame). But, on the other hand, this mode is the slowest as there are no asynchronous parallel calculations (everything's in the Main thread). Use this mode in case the time lag is unacceptabe for your application (you need all physics calculations to be applied in the current frame) and you want maximum simplicity and strictly determined order of execution for user code (physicsUpdate and physics callbacks).

UPDATE_MODE_ASYNC_RENDERING = 1

Asynchronous update mode. Physics update is performed asynchronously to rendering. In case of several physics ticks per one rendering frame (when the Engine framerate is lower, or catching up is performed), only the first one is executed in parallel, then the physics module waits for the completion of the rendering process, returns to the Main thread and executes the rest of the physics ticks. There is a frame lag (results of physics calculations are applied in the next frame) and there is some ambiguity regarding the time, when user code (physicsUpdate and physics callbacks) is to be executed in case of several physics ticks per one rendering frame (some part is executed before rendering while the other just after it). This mode is the fastest one and is used by default.

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.

Ptr<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.

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.

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 ( const char * data ) #

Sets user data associated with the world. In the *.world file, the data is set in the data tag.

Arguments

const char * data - New user data.

const char * 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 - 1 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 setSyncEngineUpdateWithPhysics ( bool fixed ) #

Sets a flag to synchronize the Engine FPS to physics one. Such FPS limitation allows to calculate physics each rendered frame (rather then interpolate it when this flag is unset). In this mode, there are no twitching of physical objects if they have non-linear velocities. If the Engine FPS is lower than the physics one, this flag has no effect.

Arguments

bool fixed - true to synchronize the Engine FPS to physics one; false to interpolate physics if the Engine FPS is higher.

bool isSyncEngineUpdateWithPhysics ( ) #

Returns a flag indicating if the Engine FPS is synchronized to physics one. Such FPS limitation allows to calculate physics each rendered frame (rather then interpolate it when this flag is unset). In this mode, there are no twitching of physical objects if they have non-linear velocities. If the Engine FPS is lower than the physics one, this flag has no effect.

Return value

true if the Engine FPS is synchronized to physics one; false if the physics is interpolated if the Engine 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 ( const Math::vec3 & gravity ) #

Updates the current gravity value.

Arguments

const Math::vec3 & gravity - New gravity.

Math::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.

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, const Ptr<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

const Math::Vec3 & p0 - Line start point coordinates.
const Math::Vec3 & p1 - Line end point coordinates.
int mask - Physics intersection mask. If 0 is passed, the function will return NULL.
const Vector< Ptr<Node> > & exclude - Array of nodes to be excluded.
const Ptr<PhysicsIntersection> & intersection - PhysicsIntersection class instance containing intersection data.

Return value

The first intersected object, if found; otherwise, 0.

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Ptr<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. Physics intersection shall only be detected 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 the line is an invisible traced 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. 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 the 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++)

int AppWorldLogic::update() {
	
	// initialize points of the mouse direction
	Vec3 p0, p1;

	// get the current player (camera)
	PlayerPtr player = Game::getPlayer();
	if (player.get() == NULL)
		return 0;
	// get width and height of the current application window
	int width = App::getWidth();
	int height = App::getHeight();
	// get the current X and Y coordinates of the mouse pointer
	int mouse_x = App::getMouseX();
	int mouse_y = App::getMouseY();
	// get the mouse direction from the player's position (p0) to the mouse cursor pointer (p1)
	player->getDirectionFromScreen(p0, p1, mouse_x, mouse_y, width, height);

	// create the instance of the PhysicsIntersection object to save the information about the intersection
	PhysicsIntersectionPtr intersection = PhysicsIntersection::create();
	// get an intersection
	ObjectPtr object = Physics::getIntersection(p0, p1, 1, intersection);

	// if the intersection has been occurred, change the parameter of the object's material    
	if (object)
	{
		for (int i = 0; i < object->getNumSurfaces(); i++)
		{
			object->setMaterialParameterFloat4("albedo_color", vec4(1.0f, 1.0f, 0.0f, 1.0f), i);
		}

		// if the intersected object has a shape, show the information about the intersection   
		ShapePtr shape = intersection->getShape();
		if (shape)
		{
			Log::message("physics intersection info: point: %s shape: %s\n", typeid(intersection->getPoint()).name(), typeid(shape->getType()).name());
		}
	}

	return 1;
}

Arguments

const Math::Vec3 & p0 - Line start point coordinates.
const Math::Vec3 & p1 - Line end point coordinates.
int mask - Physics intersection mask. If 0 is passed, the function will return NULL.
const Ptr<PhysicsIntersection> & intersection - PhysicsIntersection class instance containing intersection data.

Return value

The first intersected object, if found; otherwise, 0.

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Ptr<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. Physics intersection shall only be detected for objects with a matching mask. Intersection does not work for disabled objects.

Notice

This function uses world space coordinates.

Arguments

const Math::Vec3 & p0 - Line start point coordinates.
const Math::Vec3 & p1 - Line end point coordinates.
int mask - Physics intersection mask. If 0 is passed, the function will return NULL.
const Ptr<PhysicsIntersectionNormal> & intersection - PhysicsIntersectionNormal class instance containing intersection data.

Return value

The first intersected object, if found; otherwise, 0.

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, const Ptr<PhysicsIntersectionNormal> & intersection ) #

Notice

This function uses world space coordinates.

Arguments

const Math::Vec3 & p0 - Line start point coordinates.
const Math::Vec3 & p1 - Line end point coordinates.
int mask - Physics intersection mask. If 0 is passed, the function will return NULL.
const Vector< Ptr<Node> > & exclude - Array of nodes to be excluded.
const Ptr<PhysicsIntersectionNormal> & intersection - PhysicsIntersectionNormal class instance containing intersection data.

Return value

The first intersected object, if found; otherwise, 0.

Ptr<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 getCollisionTime ( ) #

Returns the duration of the collision detection phase, during which collisions between objects are found.

Return value

Collision detection phase duration, in 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.

Ptr<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 exists.

Arguments

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 setDeterministic ( bool stable ) #

Sets a value indicating if objects are updated in a definite order or not. Deterministic mode ensures that all contacts are solved in the predefined order and visualization of physics in the world is repetitive (on one computer). When this mode is enabled the Engine performs additional sorting of bodies, shapes and joints inside islands after building them. Deterministic mode is unavailable in case there are missed frames - it is simply impossible. Moreover, there may be differences between visualization of physics on different hardware (e.g., AMD and Intel).

NoticeDeterminism is guaranteed if there are no missed frames, the same Engine version is used, and the CPUs perform SSE operations similarly.
Please note that deterministic mode does not come for free, it may eat up 10-20% of the frame rate, and it also depends on the scene a lot.

Arguments

bool stable - true to indicate that the objects are updated in a definite order; false to indicate that an objects update order may change. The default is false (the update order may change).

bool isDeterministic ( ) #

Returns a value indicating if objects are updated in a definite order or not.Deterministic mode ensures that all contacts are solved in the predefined order and visualization of physics in the world is repetitive (on one computer). When this mode is enabled the Engine performs additional sorting of bodies, shapes and joints inside islands after building them. Deterministic mode is unavailable in case there are missed frames - it is simply impossible. Moreover, there may be differences between visualization of physics on different hardware (e.g., AMD and Intel).

NoticeDeterminism is guaranteed if there are no missed frames, the same Engine version is used, and the CPUs perform SSE operations similarly.
Please note that deterministic mode does not come for free, it may eat up 10-20% of the frame rate, and it also depends on the scene a lot.

Return value

true if the objects are updated in a definite order; otherwise false. The default is false (the update order may change).

void setCurrentSubframeTime ( 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++)

// AppWorldLogic.cpp

/* ... */
int AppWorldLogic::init() {
	// to prevent physics from being automatically calculated with each update, set one of the following:
	Physics::setEnabled(0)
	// or
	Physics::setScale(0)
}

int AppWorldLogic::update() {
	// add the time elapsed from the last physics update to the next time count cycle:
	Physics::setCurrentSubframeTime(Physics::getCurrentSubframeTime()+ifps));
}
/* ... */

In the example, ifps is the time between frames of the renderer.

Arguments

float time - Time to continue updating physics in seconds.

float getCurrentSubframeTime ( ) #

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.

void addUpdateNode ( const Ptr<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

const Ptr<Node> & node - Node to be updated.

void addUpdateNodes ( const Vector<Ptr<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

const Vector<Ptr<Node>> & nodes - Nodes to be updated.

int loadSettings ( const char * name, bool clear = false ) const#

Loads the physics settings from a given file.

Arguments

const char * name - Path to an XML file with desired settings.
bool clear - Clear flag. Set true to clear settings before loading (new settings shall be applied right after loading them), or false not to clear.

Return value

Returns 1 if the settings are loaded successfully; otherwise, 0.

int loadWorld ( const Ptr<Xml> & xml ) #

Loads physics settings from the Xml.

Arguments

const Ptr<Xml> & xml - Xml smart pointer.

Return value

Returns 1 if settings are loaded successfully; otherwise, 0.

int saveScene ( ) #

Saves the current physics scene (physical properties of all objects) into the buffer.

Return value

Scene buffer ID.

int restoreScene ( int id ) #

Restores the previously saved physics scene from the buffer.

Arguments

int id - Buffer ID.

Return value

Returns 1 if the scene is restored successfully; otherwise, 0.

int removeScene ( int id ) #

Removes the previously saved physics scene.

Arguments

int id - Buffer ID.

Return value

Returns 1 if the scene is removed successfully; otherwise, 0.

bool saveState ( const Ptr<Stream> & stream ) #

Saves physics settings into the stream.

Example using saveState() and restoreState() methods:

Source code (C++)

// set state
Physics::setNumIterations(1); // NumIterations = 1
	
// save state
BlobPtr blob_state = Blob::create();
Physics::saveState(blob_state);
	
// change state
Physics::setNumIterations(16); // now NumIterations = 16
	
// restore state
blob_state->seekSet(0);		// returning the carriage to the start of the blob
Physics::restoreState(blob_state); // restore NumIterations = 1

Arguments

const Ptr<Stream> & stream - Stream smart pointer.

Return value

true if settings are saved successfully; otherwise, false.

bool restoreState ( const Ptr<Stream> & stream ) #

Restores physics settings from the stream.

Example using saveState() and restoreState() methods:

Source code (C++)

// set state
Physics::setNumIterations(1); // NumIterations = 1
	
// save state
BlobPtr blob_state = Blob::create();
Physics::saveState(blob_state);
	
// change state
Physics::setNumIterations(16); // now NumIterations = 16
	
// restore state
blob_state->seekSet(0);		// returning the carriage to the start of the blob
Physics::restoreState(blob_state); // restore NumIterations = 1

Arguments

const Ptr<Stream> & stream - Stream smart pointer.

Return value

true if settings are restored successfully; otherwise, false.

bool saveSettings ( const char * name, int force = 0 ) #

Saves the current physics settings to a given file.

Arguments

const char * name - Path to an xml file to which the settings will be saved.
int force - Forced saving of physics settings.

Return value

true if the settings are saved successfully; otherwise, false.

bool saveWorld ( const Ptr<Xml> & xml, int force = 0 ) #

Saves physics settings to the given Xml node.

Arguments

const Ptr<Xml> & xml - Xml smart pointer.
int force - Forced saving of physics settings.

Return value

true if settings are saved successfully; otherwise, false.

void setStableFPS ( bool stablefps ) #

Returns a value indicating if frame time stabilization is enabled. In case the current Engine framerate is much higher than the fixed Physics framerate (e.g. 120 FPS vs 60 FPS), the physics won't be updated each rendering frame (e.g. it may update during every second frame). The resulting frame time will become unstable, shorter-longer-shorter-longer (render -> render+physics -> render -> render+physics...). This option ensures stable frame time for smoother user experience removing unwanted "hiccups" (however, the average framerate is decreased).

NoticeBy default, this option is enabled. But you can disable it to increase average framerate in case the application is used for machine learning or for grabbing frame sequences (video grabber), when smoothness is not important.

Arguments

bool stablefps - true to enable frame time stabilization; false - to disable it.

bool isStableFPS ( ) const#

NoticeBy default, this option is enabled. But you can disable it to increase average framerate in case the application is used for machine learning or for grabbing frame sequences (video grabber), when smoothness is not important.

Return value

true if frame time stabilization is enabled; otherwise, false.

void setUpdateMode ( Physics::UPDATE_MODE mode ) #

Sets the update mode to be used for physics. Physics can be updated either asynchronously (in parallel with rendering) or in the Main thread before rendering. The async mode is the fastest one and is used by default, however, it has a one-frame lag (calculation results are applied in the next frame) and some nuances regarding user code execution in some cases.

Arguments

Physics::UPDATE_MODE mode - New physics update mode to be set.

Physics::UPDATE_MODE getUpdateMode ( ) const#

Returns the current physics update mode. Physics can be updated either asynchronously (in parallel with rendering) or in the Main thread before rendering. The async mode is the fastest one and is used by default, however, it has a one-frame lag (calculation results are applied in the next frame) and some nuances regarding user code execution in some cases.

Return value

Current physics update mode.

void setMissedFrameLifetime ( float lifetime ) #

Sets the lifetime for missed frames. This value defines how long missed frames are to be kept in the catch-up buffer. In case the current Engine framerate is lower than the fixed Physics framerate, some of the physics frames get skipped and the simulation starts looking like in a slo-mo effect (e.g., if the target physics framerate is 60 FPS, when the Engine updates at 30 FPS, the simulation will look 2 times slower). The Physics module will try to catch up everything missed later, when possible (e.g. when the Engine framerate grows higher, while waiting for GPU to complete rendering). The missed frames are kept in a buffer for some time (lifetime), as it expires the frame is removed from the buffer and becomes lost forever.

Arguments

float lifetime - Lifetime for missing frame, in milliseconds. Setting too high values may result in significant memory consumption in case of low hardware capabilities (no catching-up performed with a growing number of missed frames).

float getMissedFrameLifetime ( ) const#

Return value

Lifetime for missing frame, in milliseconds. Setting too high values may result in significant memory consumption in case of low hardware capabilities (no catching-up performed with a growing number of missed frames).

Last update: 2021-04-29

Help improve this article

Was this article helpful?

Report a problem related to this article

(or select a word/phrase and press Ctrl+Enter)

Unigine::Physics Class

See Also#

Methods:

Physics Class

Enums

UPDATE_MODE#

Members

void setAngularDamping ( float damping ) #

Arguments

float getAngularDamping ( ) #

Return value

Ptr<Body> getBody ( int id ) #

Arguments

Return value

int isBody ( int id ) #

Arguments

Return value

void setBudget ( float budget ) #

Arguments

float getBudget ( ) #

Return value

void setData ( const char * data ) #

Arguments

const char * getData ( ) #

Return value

void setDistance ( float distance ) #

Arguments

float getDistance ( ) #

Return value

void setEnabled ( int enable ) #

Arguments

int isEnabled ( ) #

Return value

void setSyncEngineUpdateWithPhysics ( bool fixed ) #

Arguments

bool isSyncEngineUpdateWithPhysics ( ) #

Return value

int getFrame ( ) #

Return value

void setFrozenAngularVelocity ( float velocity ) #

Arguments

float getFrozenAngularVelocity ( ) #

Return value

void setFrozenLinearVelocity ( float velocity ) #

Arguments

float getFrozenLinearVelocity ( ) #

Return value

void setGravity ( const Math::vec3 & gravity ) #

Arguments

Math::vec3 getGravity ( ) #

Return value

void setIFps ( float ifps ) #

Arguments

float getIFps ( ) #

Return value

float getIntegrateTime ( ) #

Return value

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, const Ptr<PhysicsIntersection> & intersection ) #

Arguments

Return value

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Ptr<PhysicsIntersection> & intersection ) #

Arguments

Return value

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Ptr<PhysicsIntersectionNormal> & intersection ) #

Arguments

Return value

Ptr<Object> getIntersection ( const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, const Ptr<PhysicsIntersectionNormal> & intersection ) #

Arguments

Return value

Ptr<Joint> getJoint ( int id ) #

Arguments

Return value

int isJoint ( int id ) #

Arguments

Return value

void setLinearDamping ( float damping ) #

Arguments

float getLinearDamping ( ) #

Return value

void setMaxAngularVelocity ( float velocity ) #