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PerspectiveFrustum

PerspectiveFrustum

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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:

Members

:Number

The aspect ratio of the frustum's width to it's height.
Default Value:
  • undefined

:Number

The distance of the far plane.
Default Value:
  • 500000000.0

:Number

The angle of the field of view, in radians.
Default Value:
  • undefined

:Number

The distance of the near plane.
Default Value:
  • 1.0

:Matrix4

Gets the perspective projection matrix computed from the view frustum.
See:
  • PerspectiveFrustum#infiniteProjectionMatrix

<static> :Matrix4

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

Methods

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.

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.
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);

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.

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.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 = 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);