PerspectiveFrustum

new PerspectiveFrustum()

The viewing frustum is defined by 6 planes. Each plane is represented by a Cartesian4 object, where the x, y, and z components define the unit vector normal to the plane, and the w component is the distance of the plane from the origin/camera position.
Example:
var frustum = new Cesium.PerspectiveFrustum();
frustum.fovy = Cesium.Math.PI_OVER_THREE;
frustum.aspectRatio = canvas.clientWidth / canvas.clientHeight;
frustum.near = 1.0;
frustum.far = 2.0;
See:
Source: Scene/PerspectiveFrustum.js, line 32

Members

staticPerspectiveFrustum.infiniteProjectionMatrix :Matrix4

The perspective projection matrix computed from the view frustum with an infinite far plane.
See:
Source: Scene/PerspectiveFrustum.js, line 129

aspectRatio :Number

The aspect ratio of the frustum's width to it's height.
Default Value: undefined
Source: Scene/PerspectiveFrustum.js, line 48

far :Number

The distance of the far plane.
Default Value: 500000000.0
Source: Scene/PerspectiveFrustum.js, line 64

fovy :Number

The angle of the field of view, in radians.
Default Value: undefined
Source: Scene/PerspectiveFrustum.js, line 40

near :Number

The distance of the near plane.
Default Value: 1.0
Source: Scene/PerspectiveFrustum.js, line 56

projectionMatrix :Matrix4

Gets the perspective projection matrix computed from the view frustum.
See:
  • PerspectiveFrustum#infiniteProjectionMatrix
Source: Scene/PerspectiveFrustum.js, line 115

Methods

clone(result) → PerspectiveFrustum

Returns a duplicate of a PerspectiveFrustum instance.
Name Type Description
result PerspectiveFrustum optional The object onto which to store the result.
Returns:
The modified result parameter or a new PerspectiveFrustum instance if one was not provided.
Source: Scene/PerspectiveFrustum.js, line 204

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:
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);
Source: Scene/PerspectiveFrustum.js, line 153

equals(other) → Boolean

Compares the provided PerspectiveFrustum componentwise and returns true if they are equal, false otherwise.
Name Type Description
other PerspectiveFrustum optional The right hand side PerspectiveFrustum.
Returns:
true if they are equal, false otherwise.
Source: Scene/PerspectiveFrustum.js, line 234

getPixelSize(drawingBufferDimensions, distance, result) → Cartesian2

Returns the pixel's width and height in meters.
Name Type Default Description
drawingBufferDimensions Cartesian2 A Cartesian2 with width and height in the x and y properties, respectively.
distance Number near plane distance optional The distance to the near plane in meters.
result Cartesian2 optional The object onto which to store the result.
Returns:
The modified result parameter or a new instance of Cartesian2 with the pixel's width and height in the x and y properties, respectively.
Throws:
  • DeveloperError : drawingBufferDimensions.x must be greater than zero.
  • DeveloperError : drawingBufferDimensions.y must be greater than zero.
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 = Cesium.Cartesian3.subtract(primitive.boundingVolume.center, position);      // vector from camera to a primitive
var toCenterProj = Cesium.Cartesian3.multiplyByScalar(direction, Cesium.Cartesian3.dot(direction, toCenter)); // project vector onto camera direction vector
var distance = Cesium.Cartesian3.magnitude(toCenterProj);
var pixelSize = camera.frustum.getPixelSize({
    width : canvas.clientWidth,
    height : canvas.clientHeight
}, distance);
Source: Scene/PerspectiveFrustum.js, line 192