PerspectiveFrustum

var frustum = new PerspectiveFrustum();
frustum.fovy = CesiumMath.PI_OVER_THREE;
frustum.aspectRatio = canvas.clientWidth / canvas.clientHeight;
frustum.near = 1.0;
frustum.far = 2.0;

Members

aspectRatio :Number

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

Default Value:

• undefined

far :Number

The distance of the far plane.

Default Value:

• 500000000.0

fovy :Number

The angle of the field of view, in radians.

Default Value:

• undefined

near :Number

The distance of the near plane.

Default Value:

• 1.0

<static> infiniteProjectionMatrix :Matrix4

The perspective projection matrix computed from the view frustum with an infinite far plane.

See:

• PerspectiveFrustum#projectionMatrix

<static> projectionMatrix :Matrix4

The perspective projection matrix computed from the view frustum.

See:

• PerspectiveFrustum#infiniteProjectionMatrix

Methods

clone

Returns a duplicate of a PerspectiveFrustum instance.

Parameters:

Name	Type	Argument	Description
result	PerspectiveFrustum	<optional>	The object onto which to store the result.

Returns:

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

computeCullingVolume

Creates a culling volume for this frustum.

Parameters:

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

Throws:

• DeveloperError : position is required.
• DeveloperError : direction is required.
• DeveloperError : up is required.

Returns:

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.getVisibility(boundingVolume);

equals

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

Parameters:

Name	Type	Argument	Description
other	PerspectiveFrustum	<optional>	The right hand side PerspectiveFrustum.

Returns:

Boolean true if they are equal, false otherwise.

getPixelSize

Returns the pixel's width and height in meters.

Parameters:

Name	Type	Argument	Default	Description
drawingBufferDimensions	Cartesian2			A Cartesian2 with width and height in the x and y properties, respectively.
distance	Number	<optional>	near plane distance	The distance to the near plane in meters.
result	Cartesian2	<optional>		The object onto which to store the result.

Throws:

• DeveloperError : drawingBufferDimensions is required.
• DeveloperError : drawingBufferDimensions.x must be greater than zero.
• DeveloperError : drawingBufferDimensions.y must be greater than zero.

Returns:

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.

Example

// Example 1
// Get the width and height of a pixel.
var pixelSize = camera.frustum.getPixelSize({
    width : canvas.clientWidth,
    height : canvas.clientHeight
});

// 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 = Cartesian3.subtract(primitive.boundingVolume.center, position);      // vector from camera to a primitive
var toCenterProj = Cartesian3.multiplyByScalar(direction, Cartesian3.dot(direction, toCenter)); // project vector onto camera direction vector
var distance = Cartesian3.magnitude(toCenterProj);
var pixelSize = camera.frustum.getPixelSize({
    width : canvas.clientWidth,
    height : canvas.clientHeight
}, distance);