AddObject Method

Package

Class

Index

Poisson AddObject Method

Poisson allows the creation of conductors and charge densities using the addObject method:

addObject(String name, String attributes)

The obejcts usually, but not always, have an on-screen representation. The first argument is the name of the object to be added, and the second is a comma-delimited list of parameters. A circle can now be added to either applet using the following JavaScript statement:

id = document.physletname.addObject("circle", "x=0,y=-1.0,r=10");.

The addObject method is very forgiving since not all parameters need to be specified. Default values are overridden only if the parameter appears in the list. Incorrect and unsupported parameters do not affect the applet and are ignored.

The table below lists the name and the associated parameters for the Poisson Physlet. Consult the online documentation for information about other Physlets. OpticsBench, for example, supports the addObject method for lenses, mirrors, and light sources.

Name	Attributes
arrow Arrows are often animation slaves of other objects. They can represent almost any vector since the h and v components can be functions of the variables.	x- double position of the base in world units y- double position of the base in world units. h- string horizontal component v- string vertical component s -int size of arrowhead
box A hollow rectangle.	x- double position of the base in world units y- double position of the base in world units. h- int height in pixels w- int width in pixels
caption	x- double position of the base in world units y- double position of the base in world units. txt- string text
charge or chargedensity	x- double position of the base in world units y- double position of the base in world units. q- double the charge density w- int the width of the object in pixels h- int the height of the object in pixels Choose either circle, ring, or box selectors. A rectangle will be drawn if no selector is specified. circle a circular conductor. r- int the radius of the circle box a hollow rectangular conductor. s- int the thickness of the box walls in pixels ring a hollow circular conductor. r- int the radius of the circle s- int the thickness of the box walls in pixels Example: addObject("conductor","box, x=1, y=2, w=20, h=50, s=4");
circle A filled circle.	x- double position of the base in world units y- double position of the base in world units. r- int radius in pixels
conductor	x- double x position of the center in world units y- double y position of the center in world units. v- double the voltage w- int the width of the object in pixels h- int the height of the object in pixels Choose either circle, ring, or box selectors. A rectangle will be drawn if no selector is specified. circle a circular conductor. r- int the radius of the circle box a circular conductor. s- int the thickness of the box walls in pixels ring a circular conductor. r- int the radius of the circle s- int the thickness of the box walls in pixels Example: addObject("conductor","box, x=1, y=2, w=20, h=50, s=4");
constraint A constraint on dragged objects.	xmin- double minimum x xmax- double maximum x ymin- double minimum y ymax- double maximum y
dielectric	x- double x position of the center in world units y- double y position of the center in world units. v- double the voltage w- int the width of the object in pixels h- int the height of the object in pixels Choose either circle, ring, or box selectors. A rectangle will be drawn if no selector is specified. circle a circular conductor. r- int the radius of the circle box a circular conductor. s- int the thickness of the box walls in pixels ring a circular conductor. r- int the radius of the circle s- int the thickness of the box walls in pixels Example: addObject("dielectric","box, x=1, y=2, w=20, h=50, s=4");
connectorline A straight line connecting two objects.	id1- int first object identifier. id2- int second object identifier. See also: addConnectorSpring(int,int) in the online documentation. This method is easier to use if the ids are stored as integers.
contours The contour plot.	No parameters. A place-holder that determines the z-order for the contour plot. The contour plot will be drawn first unless it is explicitly added using the addObject method.
cursor A circle with crosshairs	x- double position of the base in world units y- double position of the base in world units. r- int radius in pixels
field The vector field plot.	No parameters. A place-holder that determines the z-order for the vector field plot. The vector field plot will be drawn first unless it is explicitly added using the addObject method.
function	f- string the analytic function, f(x) var- string the independent variable, x n- int the number of points used during the evaluation xmin- double the first value of x to evaluate xmax- double the last value of x to evaluate
image A gif image.	x- double position of the base in world units y- double position of the base in world units. file- string image file relative to code base
rectangle A filled rectangle.	x- double position of the base in world units y- double position of the base in world units. h- int height in pixels w- int width in pixels
shell A hollow circle.	x- double position of the base in world units y- double position of the base in world units. r- int radius in pixels
text A text message with an optional calculation.	x- double position of the base in world units y- double position of the base in world units. txt- string message calc- string an analytic function that is appended to the message. Text objects are often slaved to other objects. If a text object is slaved to an object, it takes on the properties of that object. Use the setFormat method described to change the decimal format used to output the calculation.
testcharge A test charge with a force arrow.	x- double position of the base in world units y- double position of the base in world units. r- int radius in pixels