cocos.cocosnode module

CocosNode: the basic element of cocos2d

class CocosNode

Bases: object

Cocosnode is the main element. Anything thats gets drawn or contains things that get drawn is a cocosnode. The most popular cocosnodes are scenes, layers and sprites.

The main features of a cocosnode are:
  • They can contain other cocos nodes (add, get, remove, etc)
  • They can schedule periodic callback (schedule, schedule_interval, etc)
  • They can execute actions (do, pause, stop, etc)

Some cocosnodes provide extra functionality for them or their children.

Subclassing a cocosnode usually means (one/all) of:
  • overriding __init__ to initialize resources and schedule calbacks
  • create callbacks to handle the advancement of time
  • overriding draw to render the node
add(child, z=0, name=None)

Adds a child and if it becomes part of the active scene calls its on_enter method

Parameters:
child : CocosNode

object to be added

z : float

the z index of self

name : str

Name of the child

Return type:

CocosNode instance

Returns:

self

are_actions_running()

Determine whether any actions are running.

do(action, target=None)

Executes an action. When the action finished, it will be removed from the node’s actions container.

Parameters:
action : an Action instance

Action that will be executed.

Return type:

Action instance

Returns:

A clone of action

to remove an action you must use the .do return value to call .remove_action

draw(*args, **kwargs)

This is the function you will have to override if you want your subclassed to draw something on screen.

You must respect the position, scale, rotation and anchor attributes. If you want OpenGL to do the scaling for you, you can:

def draw(self):
    glPushMatrix()
    self.transform()
    # ... draw ..
    glPopMatrix()
get(name)

Gets a child given its name

Parameters:
name : string

name of the reference to be get

Return type:

CocosNode

Returns:

the child named ‘name’. Will raise Exception if not present

Warning: if a node is added with name, then removed not by name, the name cannot be recycled: attempting to add other node with this name will produce an Exception.

get_ancestor(klass)

Walks the nodes tree upwards until it finds a node of the class klass or returns None

Return type:CocosNode or None
get_children()

Return a list with the node’s childs, order is back to front

Return type:list of CocosNode
Returns:childs of this node, ordered back to front
get_local_inverse()

returns an euclid.Matrix3 with the local inverse transformation matrix

Return type:euclid.Matrix3
get_local_transform()

returns an euclid.Matrix3 with the local transformation matrix

Return type:euclid.Matrix3
get_world_inverse()

returns an euclid.Matrix3 with the world inverse transformation matrix

Return type:euclid.Matrix3
get_world_transform()

returns an euclid.Matrix3 with the world transformation matrix

Return type:euclid.Matrix3
kill()

Remove this object from its parent, and thus most likely from everything.

on_enter()

Called every time just before the node enters the stage.

scheduled calls and worker actions begins or continues to perform

Good point to do .push_handlers if you have custom ones Rule: a handler pushed there is near certain to require a .pop_handlers in the .on_exit method (else it will be called even after removed from the active scene, or, if going on stage again will be called multiple times for each event ocurrence)

on_exit()

Called every time just before the node leaves the stage

scheduled calls and worker actions are suspended, that is, will not be called until an on_enter event happens.

Most of the time you will want to .pop_handlers for all explicit .push_handlers found in on_enter

Consider to release here openGL resources created by this node, like compiled vertex lists

pause()

Suspends the execution of actions.

pause_scheduler()

Time will stop passing for this node: scheduled callbacks will not be called, worker actions will not be called

point_to_local(p)

returns an euclid.Vector2 converted to local space

Return type:euclid.Vector2
point_to_world(p)

returns an euclid.Vector2 converted to world space

Return type:euclid.Vector2
remove(obj)

Removes a child given its name or object

If the node was added with name, it is better to remove by name, else the name will be unavailable for further adds ( and will raise Exception if add with this same name is attempted)

If the node was part of the active scene, its on_exit method will be called.

Parameters:
obj : string or object

name of the reference to be removed or object to be removed

remove_action(action)

Removes an action from the node actions container, potentially calling action.stop()

If action was running, action.stop is called Mandatory interfase to remove actions in the node actions container. When skipping this there is the posibility to double call the action.stop

Parameters:
action : Action

Action to be removed Must be the return value for a .do(...) call

resume()

Resumes the execution of actions.

resume_scheduler()

Time will continue/start passing for this node and callbacks will be called, worker actions will be called

schedule(callback, *args, **kwargs)

Schedule a function to be called every frame.

The function should have a prototype that includes dt as the first argument, which gives the elapsed time, in seconds, since the last clock tick. Any additional arguments given to this function are passed on to the callback:

def callback(dt, *args, **kwargs):
    pass
Parameters:
callback : function

The function to call each frame.

This function is a wrapper to pyglet.clock.schedule. It has the additional benefit that all calllbacks are paused and resumed when the node leaves or enters a scene.

You should not have to schedule things using pyglet by yourself.

schedule_interval(callback, interval, *args, **kwargs)

Schedule a function to be called every interval seconds.

Specifying an interval of 0 prevents the function from being called again (see schedule to call a function as often as possible).

The callback function prototype is the same as for schedule.

Parameters:
callback : function

The function to call when the timer lapses.

interval : float

The number of seconds to wait between each call.

This function is a wrapper to pyglet.clock.schedule_interval. It has the additional benefit that all calllbacks are paused and resumed when the node leaves or enters a scene.

You should not have to schedule things using pyglet by yourself.

stop()

Removes all actions from the running action list

For each action running the stop method will be called, and the action will be retired from the actions container.

transform()

Apply ModelView transformations

you will most likely want to wrap calls to this function with glPushMatrix/glPopMatrix

unschedule(callback)

Remove a function from the schedule.

If the function appears in the schedule more than once, all occurances are removed. If the function was not scheduled, no error is raised.

Parameters:
callback : function

The function to remove from the schedule.

This function is a wrapper to pyglet.clock.unschedule. It has the additional benefit that all calllbacks are paused and resumed when the node leaves or enters a scene.

You should not unschedule things using pyglet that where scheduled by node.schedule/node.schedule_interface.

visit()

This function visits it’s children in a recursive way.

It will first visit the children that that have a z-order value less than 0.

Then it will call the draw method to draw itself.

And finally it will visit the rest of the children (the ones with a z-value bigger or equal than 0)

Before visiting any children it will call the transform method to apply any possible transformation.

walk(callback, collect=None)

Executes callback on all the subtree starting at self. returns a list of all return values that are not none

Parameters:
callback : function

callable, takes a cocosnode as argument

collect : list

list of visited nodes

Return type:

list

Returns:

the list of not-none return values

actions = None

list of Action objects that are running

anchor

Anchor point of the object. Children will be added at this point and transformations like scaling and rotation will use this point as the center

anchor_x

Anchor x value for transformations and adding children

anchor_y

Anchor y value for transformations and adding children

camera = None

eye, center and up vector for the Camera. gluLookAt() is used with these values. Default: FOV 60, center of the screen. IMPORTANT: The camera can perform exactly the same transformation as scale, rotation and the x, y attributes (with the exception that the camera can modify also the z-coordinate) In fact, they all transform the same matrix, so use either the camera or the other attributes, but not both since the camera will be overridden by the transformations done by the other attributes. You can change the camera manually or by using the Camera3DAction action.

children = None

list of (int, child-reference) where int is the z-order, sorted by ascending z (back to front order)

children_names = None

dictionary that maps children names with children references

grid = None

the grid object for the grid actions. This can be a Grid3D or a TiledGrid3D object depending on the action.

is_running = None

whether of not the object is running

parent

The parent of this object.

Type:object
position

The (x, y) coordinates of the object.

Type:(int, int)
rotation
scale
scale_x
scale_y
scheduled_calls = None

list of scheduled callbacks

scheduled_interval_calls = None

list of scheduled interval callbacks

skip_frame = None

whether or not the next frame will be skipped

to_remove = None

list of Action objects to be removed

transform_anchor

Transformation anchor point. Transformations like scaling and rotation will use this point as it’s center

transform_anchor_x = None

offset from (x,0) from where rotation and scale will be applied. Default: 0

transform_anchor_y = None

offset from (0,y) from where rotation and scale will be applied. Default: 0

visible = None

whether of not the object and his childrens are visible. Default: True

x

The x coordinate of the object

y

The y coordinate of the object