Difference between revisions of "Oolite JavaScript Reference: Vector3D"
m (Added rotateBy().) |
m (Changed convention of equivalences, added some more.) |
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== Methods == | == Methods == | ||
=== Constructor === | === Constructor === | ||
| − | new Vector([ [[#Vector Expressions|vectorExpression]] ]); | + | new Vector([ [[#Vector Expressions|vectorExpression]]]); |
Create a new vector with the specified value. If no value is provided, the vector is initialized to (0, 0, 0). | Create a new vector with the specified value. If no value is provided, the vector is initialized to (0, 0, 0). | ||
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Returns the distance between the target and <code>[[#Vector Expressions|vectorExpression]]</code>. | Returns the distance between the target and <code>[[#Vector Expressions|vectorExpression]]</code>. | ||
| − | <code> | + | <code>v.distanceTo(b)</code> is equivalent to <code>v.[[#subtract|subtract]](u).[[#magnitude|magnitude]]()</code>. |
=== <code>squaredDistanceTo</code> === | === <code>squaredDistanceTo</code> === | ||
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Returns the square of the distance between the target and <code>[[#Vector Expressions|vectorExpression]]</code>. | Returns the square of the distance between the target and <code>[[#Vector Expressions|vectorExpression]]</code>. | ||
| − | <code> | + | <code>v.squaredDistanceTo(u)</code> is equivalent to <code>v.[[#distanceTo|distanceTo]](u) * v.[[#distanceTo|distanceTo]](u)</code>, or <code>v.[[#subtract|subtract]](u).[[#squaredMagnitude|squaredMagnitude]]()</code>. |
=== <code>multiply</code> === | === <code>multiply</code> === | ||
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Returns the angle (in radians) between the target and <code>[[#Vector Expressions|vectorExpression]]</code>. | Returns the angle (in radians) between the target and <code>[[#Vector Expressions|vectorExpression]]</code>. | ||
| − | <code> | + | <code>v.angleTo(u)</code> is equivalent to <code>[http://www.lib.tsinghua.edu.cn/chinese/INTERNET/JavaScript/methods.html#acos_method acos](v.[[#direction|direction]]().[[#dot|dot]](u.[[#direction|direction]]()))</code>. |
=== <code>cross</code> === | === <code>cross</code> === | ||
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Returns the [http://en.wikipedia.org/wiki/Vector_%28spatial%29#Triple_product triple product] of the target, <code>[[#Vector Expressions|vectorExpression1]]</code> and <code>[[#Vector Expressions|vectorExpression2]]</code>. | Returns the [http://en.wikipedia.org/wiki/Vector_%28spatial%29#Triple_product triple product] of the target, <code>[[#Vector Expressions|vectorExpression1]]</code> and <code>[[#Vector Expressions|vectorExpression2]]</code>. | ||
| − | <code> | + | <code>v.tripleProduct(u, w)</code> is equivalent to <code>v.[[#dot|dot]](u.[[#cross|cross]](w))</code>. |
=== <code>direction</code> === | === <code>direction</code> === | ||
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Returns the [http://en.wikipedia.org/wiki/Unit_vector unit vector] with the same direction as the target. | Returns the [http://en.wikipedia.org/wiki/Unit_vector unit vector] with the same direction as the target. | ||
| − | <code> | + | <code>v.direction()</code> is equivalent to <code>v.[[#multiply|multiply]](1 / v.[[#magnitude|magnitude]]())</code>. |
=== <code>magnitude</code> === | === <code>magnitude</code> === | ||
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Returns the square of the magnitude of the vector. | Returns the square of the magnitude of the vector. | ||
| − | <code> | + | <code>v.squaredMagnitude()</code> is equivalent to <code>v.[[#magnitude|magnitude]]() * v.[[#magnitude|magnitude]]()</code>. |
=== <code>rotateBy</code> === | === <code>rotateBy</code> === | ||
Revision as of 16:45, 7 April 2007
The Vector class is a geometrical vector in three-dimensional space, in cartesian representation. It is used to represent positions, headings and velocities. Explaining vector geometry is beyond the scope of this document, but there are numerous tutorials on the web.
Contents
Vector Expressions
All Oolite-provided functions which take a vector as an argument may instead be passed an Entity instead, in which case the entity’s position is used. In specifications, this is represented by arguments named vectorOrEntity.
Additionally, most Vector methods may be passed three numbers instead of a vector. In specifications, this is represented by arguments named vectorExpression. For example, if a and b are vectors whose values are (0, 1, 0) and (1, 0, 0) respectively, the following are equivalent:
var c = a.add(b); var d = a.add(1, 0, 0); // c and d are now both (1, 1, 0).
Properties
x
x [read-write double]
The x co-ordinate of the vector.
y
y [read-write double]
The y co-ordinate of the vector.
z
z [read-write double]
The z co-ordinate of the vector.
Methods
Constructor
new Vector([ vectorExpression]);
Create a new vector with the specified value. If no value is provided, the vector is initialized to (0, 0, 0).
add
Vector add(vectorExpression);
Returns the vector sum of the target and vectorExpression.
subtract
Vector subtract(vectorExpression);
Returns the vector difference between the target and vectorExpression.
distanceTo
double distanceTo(vectorExpression);
Returns the distance between the target and vectorExpression.
v.distanceTo(b) is equivalent to v.subtract(u).magnitude().
squaredDistanceTo
double squaredDistanceTo(vectorExpression);
Returns the square of the distance between the target and vectorExpression.
v.squaredDistanceTo(u) is equivalent to v.distanceTo(u) * v.distanceTo(u), or v.subtract(u).squaredMagnitude().
multiply
Vector multiply(number);
Returns the product of the target and vectorExpression.
dot
double dot(vectorExpression);
Returns the dot product of the target and vectorExpression.
angleTo
double angleTo(vectorExpression);
Returns the angle (in radians) between the target and vectorExpression.
v.angleTo(u) is equivalent to acos(v.direction().dot(u.direction())).
cross
double cross(vectorExpression);
Returns the cross product of the target and vectorExpression.
tripleProduct
double tripleProduct(vectorExpression1, vectorExpression2);
Returns the triple product of the target, vectorExpression1 and vectorExpression2.
v.tripleProduct(u, w) is equivalent to v.dot(u.cross(w)).
direction
Vector direction();
Returns the unit vector with the same direction as the target.
v.direction() is equivalent to v.multiply(1 / v.magnitude()).
magnitude
double magnitude();
Returns the magnitude (or length) of the vector.
squaredMagnitude
double squaredMagnitude();
Returns the square of the magnitude of the vector.
v.squaredMagnitude() is equivalent to v.magnitude() * v.magnitude().
rotateBy
Vector rotateBy(quaternionExpression);
Apply the rotation specified by quaternionExpression to the target.
rotationTo
Quaternion rotationTo(vectorExpression [, maxArc]);
Returns a quaternion corresponding to a rotation from the target to vectorExpression. The optional double parameter maxArc specifies a maximum rotation angle; if the angle between the target and vectorExpression is greater than maxArc radians, a rotation of maxArc radians towards vectorExpression is generated instead.
