Class: PerspectiveOffCenterFrustum

PerspectiveOffCenterFrustum

new PerspectiveOffCenterFrustum()

Each plane is represented by a Cartesian object, where the x, y, and z components define the unit normal vector of the plane, and the w component is the distance between the plane and the origin/camera position.

Name Type Default Description
options.left Number optional

The distance of the left clipping plane.
options.right Number optional

The distance of the right clipping plane.
options.top Number optional

The distance of the upper cutting plane.
options.bottom Number optional

The distance of the cutting plane.
options.near Number 1.0 optional

The distance to the cutting plane.
options.far Number 500000000.0 optional

Distance from the far cutting plane.
See:
Example
var frustum = new SuperMap3D.PerspectiveOffCenterFrustum({
    left : -1.0,
    right : 1.0,
    top : 1.0,
    bottom : -1.0,
    near : 1.0,
    far : 100.0
});

Members

bottomNumber

Define the bottom clipping plane.

Default Value:
undefined

farNumber

Distance from the far plane.

Default Value:
500000000.0

readonly infiniteProjectionMatrixMatrix4

Obtain the perspective projection matrix calculated from an infinite plane cone.

See:

leftNumber

Define the left clipping plane.

Default Value:
undefined

nearNumber

Distance near the plane.

Default Value:
1.0

readonly projectionMatrixMatrix4

Obtain the perspective projection matrix calculated based on the viewing cone.

See:

Define the right clipping plane.

Default Value:
undefined

topNumber

Define the top clipping plane.

Default Value:
undefined

Methods

clone(result){PerspectiveOffCenterFrustum}

Return a copy of the PerspectiveOffCenterFrustum instance.

Name Type Description
result PerspectiveOffCenterFrustum optional

The object that stores the results.
Returns:
Type Description
PerspectiveOffCenterFrustum The modified result parameters, or a new PerspectiveFrustum instance (if not provided).

computeCullingVolume(position, direction, up){CullingVolume}

Create a cropped body for this viewing cone.

Name Type Description
position Cartesian3

Viewpoint position.
direction Cartesian3

Direction of gaze.
up Cartesian3

Upward direction.
Returns:
Type Description
CullingVolume A cropped object in a given position and direction.
Example
// Check if a bounding volume intersects the frustum.
var cullingVolume = frustum.computeCullingVolume(cameraPosition, cameraDirection, cameraUp);
var intersect = cullingVolume.computeVisibility(boundingVolume);

equals(other){Boolean}

Compare the provided PerspectiveOffCenterFrustum components, return true if they are equal, otherwise return false.

Name Type Description
other PerspectiveOffCenterFrustum optional

The Perspective Off Center Frustum on the right
Returns:
Type Description
Boolean If they are equal, it is true; otherwise, it is false.

equalsEpsilon(other, relativeEpsilon, absoluteEpsilon){Boolean}

If the provided PerspectiveOffCenterFrustum components meet the inspection criteria for absolute or relative tolerances, return true; otherwise, return false.

Name Type Default Description
other PerspectiveOffCenterFrustum

The visual cone to be compared.
relativeEpsilon Number

The relative epsilon tolerance value used for equality testing.
absoluteEpsilon Number relativeEpsilon optional

The absolute epsilon tolerance value used for equality testing.
Returns:
Type Description
Boolean If this object and other objects are within the provided epsilon range, return true; otherwise, return false.

getPixelDimensions(drawingBufferWidth, drawingBufferHeight, distance, result){Cartesian2}

Returns the width and height of pixels in meters.

Name Type Description
drawingBufferWidth Number

Draw the width of the buffer.
drawingBufferHeight Number

Draw the height of the buffer.
distance Number

The distance to the near plane, measured in meters.
result Cartesian2

The object that stores the results.
Throws:

  • drawingBufferWidth must be greater than zero.

    Type
    DeveloperError

  • drawingBufferHeight must be greater than zero.

    Type
    DeveloperError
Returns:
Type Description
Cartesian2 The modified result parameter or a new instance of Cartesian2 contains the width and height of the pixel in its x and y attributes, respectively.
Examples
// Example 1
// Get the width and height of a pixel.
var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, 1.0, new SuperMap3D.Cartesian2());
// Example 2
// Get the width and height of a pixel if the near plane was set to 'distance'.
// For example, get the size of a pixel of an image on a billboard.
var position = camera.position;
var direction = camera.direction;
var toCenter = SuperMap3D.Cartesian3.subtract(primitive.boundingVolume.center, position, new SuperMap3D.Cartesian3());      // vector from camera to a primitive
var toCenterProj = SuperMap3D.Cartesian3.multiplyByScalar(direction, SuperMap3D.Cartesian3.dot(direction, toCenter), new SuperMap3D.Cartesian3()); // project vector onto camera direction vector
var distance = SuperMap3D.Cartesian3.magnitude(toCenterProj);
var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, distance, new SuperMap3D.Cartesian2());