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peon::Vector2 Class Reference

Standard 2-dimensional vector. More...

#include <Vector2.h>

List of all members.

Public Member Functions

 Vector2 (Real fX, Real fY)
 Vector2 (Real afCoordinate[2])
 Vector2 (int afCoordinate[2])
 Vector2 (const Real *const r)
 Vector2 (const Vector2 &rkVector)
Real operator[] (size_t i) const
Realoperator[] (size_t i)
Vector2operator= (const Vector2 &rkVector)
 Assigns the value of the other vector.
bool operator== (const Vector2 &rkVector) const
bool operator!= (const Vector2 &rkVector) const
Vector2 operator+ (const Vector2 &rkVector) const
Vector2 operator- (const Vector2 &rkVector) const
Vector2 operator * (Real fScalar) const
Vector2 operator * (const Vector2 &rhs) const
Vector2 operator/ (Real fScalar) const
Vector2 operator- () const
Vector2operator+= (const Vector2 &rkVector)
Vector2operator-= (const Vector2 &rkVector)
Vector2operator *= (Real fScalar)
Vector2operator/= (Real fScalar)
Real length () const
 Returns the length (magnitude) of the vector.
Real squaredLength () const
 Returns the square of the length(magnitude) of the vector.
Real dotProduct (const Vector2 &vec) const
 Calculates the dot (scalar) product of this vector with another.
Real normalise ()
 Normalises the vector.
Vector2 midPoint (const Vector2 &vec) const
 Returns a vector at a point half way between this and the passed in vector.
bool operator< (const Vector2 &rhs) const
 Returns true if the vector's scalar components are all greater that the ones of the vector it is compared against.
bool operator> (const Vector2 &rhs) const
 Returns true if the vector's scalar components are all smaller that the ones of the vector it is compared against.
void makeFloor (const Vector2 &cmp)
 Sets this vector's components to the minimum of its own and the ones of the passed in vector.
void makeCeil (const Vector2 &cmp)
 Sets this vector's components to the maximum of its own and the ones of the passed in vector.
Vector2 perpendicular (void) const
 Generates a vector perpendicular to this vector (eg an 'up' vector).
Vector2 crossProduct (const Vector2 &rkVector) const
 Calculates the cross-product of 2 vectors, i.e.
Vector2 randomDeviant (Real angle) const
 Generates a new random vector which deviates from this vector by a given angle in a random direction.
bool isZeroLength (void) const
 Returns true if this vector is zero length.
Vector2 normalisedCopy (void) const
 As normalise, except that this vector is unaffected and the normalised vector is returned as a copy.
Vector2 reflect (const Vector2 &normal)
 Calculates a reflection vector to the plane with the given normal .

Static Public Attributes

static const Vector2 ZERO
static const Vector2 UNIT_X
static const Vector2 UNIT_Y
static const Vector2 NEGATIVE_UNIT_X
static const Vector2 NEGATIVE_UNIT_Y
static const Vector2 UNIT_SCALE

Friends

Vector2 operator * (Real fScalar, const Vector2 &rkVector)


Detailed Description

Standard 2-dimensional vector.

Remarks:
A direction in 2D space represented as distances along the 2 orthoganal axes (x, y). Note that positions, directions and scaling factors can be represented by a vector, depending on how you interpret the values.


Member Function Documentation

Vector2 peon::Vector2::crossProduct const Vector2 rkVector  )  const [inline]
 

Calculates the cross-product of 2 vectors, i.e.

the vector that lies perpendicular to them both.

Remarks:
The cross-product is normally used to calculate the normal vector of a plane, by calculating the cross-product of 2 non-equivalent vectors which lie on the plane (e.g. 2 edges of a triangle).
Parameters:
vec Vector which, together with this one, will be used to calculate the cross-product.
Returns:
A vector which is the result of the cross-product. This vector will NOT be normalised, to maximise efficiency
  • call Vector3::normalise on the result if you wish this to be done. As for which side the resultant vector will be on, the returned vector will be on the side from which the arc from 'this' to rkVector is anticlockwise, e.g. UNIT_Y.crossProduct(UNIT_Z) = UNIT_X, whilst UNIT_Z.crossProduct(UNIT_Y) = -UNIT_X.
For a clearer explanation, look a the left and the bottom edges of your monitor's screen. Assume that the first vector is the left edge and the second vector is the bottom edge, both of them starting from the lower-left corner of the screen. The resulting vector is going to be perpendicular to both of them and will go inside the screen, towards the cathode tube (assuming you're using a CRT monitor, of course).

Real peon::Vector2::dotProduct const Vector2 vec  )  const [inline]
 

Calculates the dot (scalar) product of this vector with another.

Remarks:
The dot product can be used to calculate the angle between 2 vectors. If both are unit vectors, the dot product is the cosine of the angle; otherwise the dot product must be divided by the product of the lengths of both vectors to get the cosine of the angle. This result can further be used to calculate the distance of a point from a plane.
Parameters:
vec Vector with which to calculate the dot product (together with this one).
Returns:
A float representing the dot product value.

Real peon::Vector2::length  )  const [inline]
 

Returns the length (magnitude) of the vector.

Warning:
This operation requires a square root and is expensive in terms of CPU operations. If you don't need to know the exact length (e.g. for just comparing lengths) use squaredLength() instead.

void peon::Vector2::makeCeil const Vector2 cmp  )  [inline]
 

Sets this vector's components to the maximum of its own and the ones of the passed in vector.

Remarks:
'Maximum' in this case means the combination of the highest value of x, y and z from both vectors. Highest is taken just numerically, not magnitude, so 1 > -3.

void peon::Vector2::makeFloor const Vector2 cmp  )  [inline]
 

Sets this vector's components to the minimum of its own and the ones of the passed in vector.

Remarks:
'Minimum' in this case means the combination of the lowest value of x, y and z from both vectors. Lowest is taken just numerically, not magnitude, so -1 < 0.

Real peon::Vector2::normalise  )  [inline]
 

Normalises the vector.

Remarks:
This method normalises the vector such that it's length / magnitude is 1. The result is called a unit vector.
Note:
This function will not crash for zero-sized vectors, but there will be no changes made to their components.
Returns:
The previous length of the vector.

Vector2& peon::Vector2::operator= const Vector2 rkVector  )  [inline]
 

Assigns the value of the other vector.

Parameters:
rkVector The other vector

Vector2 peon::Vector2::perpendicular void   )  const [inline]
 

Generates a vector perpendicular to this vector (eg an 'up' vector).

Remarks:
This method will return a vector which is perpendicular to this vector. There are an infinite number of possibilities but this method will guarantee to generate one of them. If you need more control you should use the Quaternion class.

Vector2 peon::Vector2::randomDeviant Real  angle  )  const [inline]
 

Generates a new random vector which deviates from this vector by a given angle in a random direction.

Remarks:
This method assumes that the random number generator has already been seeded appropriately.
Parameters:
angle The angle at which to deviate in radians
up Any vector perpendicular to this one (which could generated by cross-product of this vector and any other non-colinear vector). If you choose not to provide this the function will derive one on it's own, however if you provide one yourself the function will be faster (this allows you to reuse up vectors if you call this method more than once)
Returns:
A random vector which deviates from this vector by angle. This vector will not be normalised, normalise it if you wish afterwards.

Vector2 peon::Vector2::reflect const Vector2 normal  )  [inline]
 

Calculates a reflection vector to the plane with the given normal .

Remarks:
NB assumes 'this' is pointing AWAY FROM the plane, invert if it is not.

Real peon::Vector2::squaredLength  )  const [inline]
 

Returns the square of the length(magnitude) of the vector.

Remarks:
This method is for efficiency - calculating the actual length of a vector requires a square root, which is expensive in terms of the operations required. This method returns the square of the length of the vector, i.e. the same as the length but before the square root is taken. Use this if you want to find the longest / shortest vector without incurring the square root.


The documentation for this class was generated from the following file:
Generated on Wed Nov 9 09:37:08 2005 for Peon by  doxygen 1.4.3