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.PerspectiveOffCenterFrustum();
frustum.right = 1.0;
frustum.left = -1.0;
frustum.top = 1.0;
frustum.bottom = -1.0;
frustum.near = 1.0;
frustum.far = 2.0;
See:
Members
-
Defines the bottom clipping plane.
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Default Value:
undefined
-
The distance of the far plane.
-
Default Value:
500000000.0
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readonlyinfiniteProjectionMatrix : Matrix4
-
Gets the perspective projection matrix computed from the view frustum with an infinite far plane.
-
Defines the left clipping plane.
-
Default Value:
undefined
-
The distance of the near plane.
-
Default Value:
1.0
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readonlyprojectionMatrix : Matrix4
-
Gets the perspective projection matrix computed from the view frustum.
-
Defines the right clipping plane.
-
Default Value:
undefined
-
Defines the top clipping plane.
-
Default Value:
undefined
Methods
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clone(result) → PerspectiveOffCenterFrustum
-
Returns a duplicate of a PerspectiveOffCenterFrustum instance.
Name Type Description result
PerspectiveOffCenterFrustum optional The object onto which to store the result. Returns:
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:
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);
-
Compares the provided PerspectiveOffCenterFrustum componentwise and returns
true
if they are equal,false
otherwise.Name Type Description other
PerspectiveOffCenterFrustum optional The right hand side PerspectiveOffCenterFrustum. Returns:
true
if they are equal,false
otherwise. -
getPixelDimensions(drawingBufferWidth, drawingBufferHeight, distance, 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. result
Cartesian2 The object onto which to store the result. Returns:
The modified result parameter or a new instance ofCartesian2
with the pixel's width and height in the x and y properties, respectively.Throws:
-
DeveloperError : drawingBufferWidth must be greater than zero.
-
DeveloperError : drawingBufferHeight must be greater than zero.
Examples:
// Example 1 // Get the width and height of a pixel. var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, 1.0, new 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 = Cesium.Cartesian3.subtract(primitive.boundingVolume.center, position, new Cesium.Cartesian3()); // vector from camera to a primitive var toCenterProj = Cesium.Cartesian3.multiplyByScalar(direction, Cesium.Cartesian3.dot(direction, toCenter), new Cesium.Cartesian3()); // project vector onto camera direction vector var distance = Cesium.Cartesian3.magnitude(toCenterProj); var pixelSize = camera.frustum.getPixelDimensions(scene.drawingBufferWidth, scene.drawingBufferHeight, distance, new Cartesian2());
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