Class: GrinGlass

sceneObjs.GrinGlass()

Gradient-index glass of the shape of a polygon

Tools -> Glass -> Gradient-index polygon

Constructor

new GrinGlass()

Properties:
Name Type Description
path Array.<Point>

The path of the glass. Each element is an object with x and y properties for coordinates.
notDone boolean

Whether the user is still drawing the glass.
refIndexFn string

The refractive index function in x and y in LaTeX format.
origin Point

The origin of the (x,y) coordinates used in the refractive index function.
stepSize number

The step size for the ray trajectory equation.
intersectTol number

The epsilon for the intersection calculations.
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Extends

Members

error

Properties:
Name Type Description
error string | null

The error message of the object.
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isOptical

Whether the object is optical (i.e. is a light source, interacts with rays, or detects rays).

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scene

Properties:
Name Type Description
scene Scene

The scene the object belongs to.
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serializableDefaults

The default values of the properties of the object which are to be serialized. The keys are the property names and the values are the default values. If some properties is default, they will not be serialized and will be deserialized to the default values.

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supportsSurfaceMerging

Whether the object supports surface merging. (This is currently only for glasses, where the surfaces of two glasses are merged to form a single surface if the surfaces overlap.)

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type

The type of the object.

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warning

Properties:
Name Type Description
warning string | null

The warning message of the object.
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Methods

arePropertiesDefault(propertyNames) → {boolean}

Check whether the given properties of the object are all the default values.

Parameters:
Name Type Description
propertyNames Array.<string>

The property names to be checked.
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Returns:

Whether the properties are all the default values.

Type
boolean

checkMouseOver(mouse) → {DragContext|null}

Check whether the mouse is over the object, which is called when the user moves the mouse over the scene. This is used for deciding the highlighting of the object, and also for deciding that if the user starts dragging at this position, which part of the object should be dragged.

Parameters:
Name Type Description
mouse Mouse

The mouse object.
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Returns:

The drag context if the user starts dragging at this position, or null if the mouse is not over the object.

Type
DragContext | null

checkRayIntersects(ray) → {Point|null}

Check whether the object intersects with the given ray. Called during the ray tracing when ray is to be tested whether it intersects with the object. Find whether they intersect and find the nearset intersection if so. Implemented only by optical elements that affects or detect rays.

Parameters:
Name Type Description
ray Ray

The ray.
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Returns:
  • The intersection (closest to the beginning of the ray) if they intersect.
Type
Point | null

devRefIndex(bodyMergingObj) → {BodyMergingObj}

Receives a bodyMerging object and returns a new bodyMerging object for the region of bodyMergingObj excluding current GRIN glass.

Parameters:
Name Type Description
bodyMergingObj BodyMergingObj
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Returns:
Type
BodyMergingObj

draw(canvasRenderer, isAboveLight, isHovered)

Draw the object on the canvas. Called once before the simulator renders the light with isAboveLight === false and once after with isAboveLight === true. Due to historical reason, some objects use this function to do some initialization. This should be avoided in the future.

Parameters:
Name Type Description
canvasRenderer CanvasRenderer

The canvas renderer.
isAboveLight boolean

Whether the rendering layer is above the light layer.
isHovered boolean

Whether the object is hovered by the mouse, which determines the style of the object to be drawn, e.g., with lighlighted color.
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fillGlass(canvasRenderer, isAboveLight, isHovered)

Fill the glass with the color that represents the refractive index. To be called in draw of a subclass when the path has been set up with canvasRenderer.ctx.beginPath(), etc.

Parameters:
Name Type Description
canvasRenderer CanvasRenderer

The canvas renderer.
isAboveLight boolean

Whether the rendering layer is above the light layer.
isHovered boolean

Whether the object is hovered by the mouse, which determines the style of the object to be drawn, e.g., with lighlighted color.
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getError() → {string|null}

Get the error message of the object.

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Returns:

The error message.

Type
string | null

getIncidentType(ray) → {number}

Get whether the ray is incident from inside to outside or from outside to inside.

Parameters:
Name Type Description
ray Ray

The ray to be checked.
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Returns:
  • 1 if the ray is incident from inside to outside, -1 if the ray is incident from outside to inside, 0 if the ray is equivalent to not intersecting the glass (e.g. intersecting with two overlapping surfaces of the glass), and NaN for other situations (e.g. parallel to a surface).
Type
number

getRefIndexAt(point, ray) → {number}

Get the refractive index at a point for a ray

Parameters:
Name Type Description
point Point

The point to get the refractive index. For normal glasses, this parameter is not used. But it will be used in GRIN glasses.
ray Ray

The ray to be refracted.
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Returns:
  • The refractive index at the point.
Type
number

getWarning() → {string|null}

Get the warning message of the object.

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Returns:

The warning message.

Type
string | null

getZIndex() → {number}

Get the z-index of the object for the sequence of drawing. Called before the simulator starts to draw the scene.

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Returns:

The z-index. The smaller the number is, the earlier draw is called.

Type
number

initFns()

Do the partial derivatives of the refractive index function and parse the functions.

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initRefIndex(ray) → {BodyMergingObj}

Receives a ray, and returns a bodyMerging object for the point ray.p1

Parameters:
Name Type Description
ray Ray
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Returns:
Type
BodyMergingObj

isInsideGlass(point)

Returns true if point is inside the glass, otherwise returns false

Parameters:
Name Type Description
point Point
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isOnBoundary(point)

Returns true if point is on the boundary of the glass, otherwise returns false

Parameters:
Name Type Description
point Point
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isOutsideGlass(point)

Returns true if point is outside the glass, otherwise returns false

Parameters:
Name Type Description
point Point
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move(diffX, diffY)

Move the object by the given displacement. Called when the user use arrow keys to move the object.

Parameters:
Name Type Description
diffX number

The x-coordinate displacement.
diffY number

The y-coordinate displacement.
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multRefIndex(bodyMergingObj) → {BodyMergingObj}

Receives a bodyMerging object and returns a new bodyMerging object for the overlapping region of bodyMergingObj and the current GRIN glass.

Parameters:
Name Type Description
bodyMergingObj BodyMergingObj
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Returns:
Type
BodyMergingObj

onConstructMouseDown(mouse, ctrl, shift) → {ConstructReturn}

Mouse down event when the object is being constructed by the user.

Parameters:
Name Type Description
mouse Mouse

The mouse object.
ctrl boolean

Whether the control key is pressed.
shift boolean

Whether the shift key is pressed.
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Returns:

The return value.

Type
ConstructReturn

onConstructMouseMove(mouse, ctrl, shift) → {ConstructReturn}

Mouse move event when the object is being constructed by the user.

Parameters:
Name Type Description
mouse Mouse

The mouse object.
ctrl boolean

Whether the control key is pressed.
shift boolean

Whether the shift key is pressed.
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Returns:

The return value.

Type
ConstructReturn

onConstructMouseUp(mouse, ctrl, shift) → {ConstructReturn}

Mouse up event when the object is being constructed by the user.

Parameters:
Name Type Description
mouse Mouse

The mouse object.
ctrl boolean

Whether the control key is pressed.
shift boolean

Whether the shift key is pressed.
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Returns:

The return value.

Type
ConstructReturn

onConstructUndo() → {ConstructReturn}

Undo event when the object is being constructed by the user.

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Returns:

The return value.

Type
ConstructReturn

onDrag(mouse, dragContext, ctrl, shift)

The event when the user drags the object, which is fired on every step during the dragging. The object should be updated according to DragContext which is returned by checkMouseOver. dragContext can be modified during the dragging.

Parameters:
Name Type Description
mouse Mouse

The mouse object.
dragContext DragContext

The drag context.
ctrl boolean

Whether the control key is pressed.
shift boolean

Whether the shift key is pressed.
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onRayEnter(ray)

Handle the event when a ray enters the glass. This is called during the surface merging process, and is called by the glass object who is handling the surface merging, rather than by the simulator. Unlike onRayIncident which is only called for one representative object who is responsible for handling the surface merging, this function is called for every object that consistute the merged surface. For notmal glasses nothing needs to be done in this function, but for GRIN glasses, the body-merging object in the ray should be updated here, so that the ray knows that it now feels a different refractive index gradient.

Parameters:
Name Type Description
ray Ray

The ray that enters the glass.
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onRayExit(ray)

Handle the event when a ray exits the glass. This is called during the surface merging process, and is called by the glass object who is handling the surface merging, rather than by the simulator. Unlike onRayIncident which is only called for one representative object who is responsible for handling the surface merging, this function is called for every object that consistute the merged surface. For notmal glasses nothing needs to be done in this function, but for GRIN glasses, the body-merging object in the ray should be updated here, so that the ray knows that it now feels a different refractive index gradient.

Parameters:
Name Type Description
ray Ray

The ray that exits the glass.
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onRayIncident(ray, rayIndex, incidentPoint, surfaceMergingObjs) → {SimulationReturn|null}

The event when a ray is incident on the object. Called during the ray tracing when ray has been calculated to be incident on the object at the incidentPoint. Perform the interaction between ray and the object. Implemented only by optical elements that affects or detect rays. If ray is absorbed by the object, return { isAbsorbed: true }. If there is a primary outgoing ray, directly modify ray to be the outgoing ray. This includes the case when the object is a detector that does not modify the direction of the ray. If there are secondary rays to be emitted, return { newRays: [ray1, ray2, ...] }. Note that if there are more than one secondary rays, image detection does not work in the current version, and rayN.gap should be set to true. But for future support, the secondary ray which is to be of the same continuous bunch or rays should have consistent index in the newRays array. Sometimes keeping tracks of all the rays may result in infinite loop (such as in a glass). Depending on the situation, some rays with brightness below a certain threshold (such as 0.01) may be truncated. In this case, the brightness of the truncated rays should be returned as truncation.

Parameters:
Name Type Description
ray Ray

The ray.
rayIndex number

The index of the ray in the array of all rays currently in the scene in the simulator. In particular, in a bunch of continuous rays, the rays are ordered by the time they are emitted, and the index is the order of emission. This can be used to downsample the rays and increase the individual brightness if it is too low.
incidentPoint Point

The point where the ray is incident on the object, which is the intersection point found by checkRayIntersects.
surfaceMergingObjs Array.<BaseSceneObj>

The objects that are merged with the current object. If two or more objects with supportsSurfaceMerging === true has overlapping surfaces (often acheived by using the grid), and if a ray is incident on those surfaces together, only one of the object will be have onRayIncident being called, and the other objects will be in surfaceMergingObjs. In this case, this function must also deal with the combination of the surface before doing the actual interaction. Note that treating them as two very close surfaces may not give the correct result due to an essential discontinuity of ray optics (which is smoothed out at the scale of the wavelength in reality).
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Returns:

The return value.

Type
SimulationReturn | null

onSimulationStart() → {SimulationReturn|null}

The event when the simulation starts. If this object is a light source, it should emit rays here by setting newRays. If the object is a detector, it may do some initialization here.

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Returns:

The return value.

Type
SimulationReturn | null

populateObjBar(objBar)

Populate the object bar. Called when the user selects the object (it is selected automatically when the user creates it, so the construction may not be completed at this stage).

Parameters:
Name Type Description
objBar ObjBar

The object bar to be populated.
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refract(ray, rayIndex, incidentPoint, normal, n1, surfaceMergingObjs, bodyMergingObj) → {SimulationReturn}

Do the refraction calculation at the surface of the glass.

Parameters:
Name Type Description
ray Ray

The ray to be refracted.
rayIndex number

The index of the ray in the ray array.
incidentPoint Point

The incident point.
normal Point

The normal vector at the incident point.
n1 number

The effective refractive index of the current object (after determining the direction of incident of the current object, but before merging the surface with other objects).
surfaceMergingObjs Array.<BaseSceneObj>

The objects that are to be merged with the current object.
bodyMergingObj BaseGrinGlass

The object that is to be merged with the current object.
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Returns:

The return value for onRayIncident.

Type
SimulationReturn

rotate(cw)

Rotate the object. (This feature is incomplete and currently only implemented for ConcaveDiffractionGrating.)

Parameters:
Name Type Description
cw number
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serialize() → {Object}

Serializes the object to a JSON object.

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Returns:

The serialized JSON object.

Type
Object

shiftOrigin(equation) → {string}

Shifts the x and y variables in equation from related to this.origin to the absolute coordinates.

Parameters:
Name Type Description
equation string
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Returns:
Type
string

step(p1, p2, ray)

Receives two points inside this lens, and returns the next point to where the ray, connecting these two points, will travel, based on the ray trajectory equation (equation 11.1 in the cited text below) Using Euler's method to solve the ray trajectory equation (based on sections 11.1 and 11.2, in the following text: https://doi.org/10.1007/BFb0012092) x_der_s and x_der_s_prev are the x-coordinate derivatives with respect to the arc-length parameterization, at two different points (similarly for y_der_s and y_der_s_prev)

Parameters:
Name Type Description
p1 Point
p2 Point
ray Ray
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