Class: PerspectiveFrustum

var frustum = new SuperMap3D.PerspectiveFrustum({
    fov : SuperMap3D.Math.PI_OVER_THREE,
    aspectRatio : canvas.clientWidth / canvas.clientHeight
    near : 1.0,
    far : 1000.0
});

Members

static isNDCHalfZRange

Indicates if the z range in NDC space is 0..1 (value: true) or -1..1 (value: false)

static packedLengthNumber

The number of elements used to pack the object into an array.

aspectRatioNumber

The aspect ratio of the frustum's width to it's height.

Default Value:

undefined

Methods

static pack(value, array, startingIndex){Array.<Number>}

Stores the provided instance into the provided array.

Name	Type	Default	Description
value	PerspectiveFrustum		The value to pack.
array	Array.<Number>		The array to pack into.
startingIndex	Number	0	可选 The index into the array at which to start packing the elements.

Returns:

Type	Description
Array.<Number>	The array that was packed into

static unpack(array, startingIndex, result){PerspectiveFrustum}

Retrieves an instance from a packed array.

Name	Type	Default	Description
array	Array.<Number>		The packed array.
startingIndex	Number	0	可选 The starting index of the element to be unpacked.
result	PerspectiveFrustum		可选 The object into which to store the result.

Returns:

Type	Description
PerspectiveFrustum	The modified result parameter or a new PerspectiveFrustum instance if one was not provided.

clone(result){PerspectiveFrustum}

Returns a duplicate of a PerspectiveFrustum instance.

Name	Type	Description
result	PerspectiveFrustum	可选 The object onto which to store the result.

Returns:

Type	Description
PerspectiveFrustum	The modified result parameter or a new PerspectiveFrustum instance if one was not provided.

computeCullingVolume(position, direction, up){CullingVolume}

Creates a culling volume for this frustum.

Name	Type	Description
position	Cartesian3	The eye position.
direction	Cartesian3	The view direction.
up	Cartesian3	The up direction.

Returns:

Type	Description
CullingVolume	A culling volume at the given position and orientation.

Example

// Check if a bounding volume intersects the frustum.
var cullingVolume = frustum.computeCullingVolume(cameraPosition, cameraDirection, cameraUp);
var intersect = cullingVolume.computeVisibility(boundingVolume);

equals(other){Boolean}

Compares the provided PerspectiveFrustum componentwise and returns true if they are equal, false otherwise.

Name	Type	Description
other	PerspectiveFrustum	可选 The right hand side PerspectiveFrustum.

Returns:

Type	Description
Boolean	true if they are equal, false otherwise.

equalsEpsilon(other, relativeEpsilon, absoluteEpsilon){Boolean}

Compares the provided PerspectiveFrustum componentwise and returns true if they pass an absolute or relative tolerance test, false otherwise.

Name	Type	Default	Description
other	PerspectiveFrustum		The right hand side PerspectiveFrustum.
relativeEpsilon	Number		The relative epsilon tolerance to use for equality testing.
absoluteEpsilon	Number	relativeEpsilon	可选 The absolute epsilon tolerance to use for equality testing.

Returns:

Type	Description
Boolean	true if this and other are within the provided epsilon, false otherwise.

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

Returns the pixel's width and height in meters.

Name	Type	Description
drawingBufferWidth	Number	The width of the drawing buffer.
drawingBufferHeight	Number	The height of the drawing buffer.
distance	Number	The distance to the near plane in meters.
pixelRatio	Number	The scaling factor from pixel space to coordinate space.
result	Cartesian2	The object onto which to store the result.

Throws:

• drawingBufferWidth must be greater than zero.

  Type

  DeveloperError

• drawingBufferHeight must be greater than zero.

  Type

  DeveloperError

• pixelRatio must be greater than zero.

  Type

  DeveloperError

Returns:

Type	Description
Cartesian2	The modified result parameter or a new instance of Cartesian2 with the pixel's width and height in the x and y properties, respectively.

Examples

// Example 1
// Get the width and height of a pixel.
var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, 1.0, scene.pixelRatio, 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, scene.pixelRatio, new SuperMap3D.Cartesian2());