Vector.java
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Authors: Apryse Software.
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package com.itextpdf.kernel.geom;
import java.util.Arrays;
/**
* Represents a vector (i.e. a point in space). This class is completely
* unrelated to the {@link java.util.Vector} class in the standard JRE.
* <br><br>
* For many PDF related operations, the z coordinate is specified as 1
* This is to support the coordinate transformation calculations. If it
* helps, just think of all PDF drawing operations as occurring in a single plane
* with z=1.
*/
public class Vector {
/**
* index of the X coordinate
*/
public static final int I1 = 0;
/**
* index of the Y coordinate
*/
public static final int I2 = 1;
/**
* index of the Z coordinate
*/
public static final int I3 = 2;
/**
* the values inside the vector
*/
private final float[] vals = new float[] {0, 0, 0};
/**
* Creates a new Vector
*
* @param x the X coordinate
* @param y the Y coordinate
* @param z the Z coordinate
*/
public Vector(float x, float y, float z) {
vals[I1] = x;
vals[I2] = y;
vals[I3] = z;
}
/**
* Gets the value from a coordinate of the vector
*
* @param index the index of the value to get (I1, I2 or I3)
* @return a coordinate value
*/
public float get(int index) {
return vals[index];
}
/**
* Computes the cross product of this vector and the specified matrix
*
* @param by the matrix to cross this vector with
* @return the result of the cross product
*/
public Vector cross(Matrix by) {
float x = vals[I1] * by.get(Matrix.I11) + vals[I2] * by.get(Matrix.I21) + vals[I3] * by.get(Matrix.I31);
float y = vals[I1] * by.get(Matrix.I12) + vals[I2] * by.get(Matrix.I22) + vals[I3] * by.get(Matrix.I32);
float z = vals[I1] * by.get(Matrix.I13) + vals[I2] * by.get(Matrix.I23) + vals[I3] * by.get(Matrix.I33);
return new Vector(x, y, z);
}
/**
* Computes the difference between this vector and the specified vector
*
* @param v the vector to subtract from this one
* @return the results of the subtraction
*/
public Vector subtract(Vector v) {
float x = vals[I1] - v.vals[I1];
float y = vals[I2] - v.vals[I2];
float z = vals[I3] - v.vals[I3];
return new Vector(x, y, z);
}
/**
* Computes the cross product of this vector and the specified vector
*
* @param with the vector to cross this vector with
* @return the cross product
*/
public Vector cross(Vector with) {
float x = vals[I2] * with.vals[I3] - vals[I3] * with.vals[I2];
float y = vals[I3] * with.vals[I1] - vals[I1] * with.vals[I3];
float z = vals[I1] * with.vals[I2] - vals[I2] * with.vals[I1];
return new Vector(x, y, z);
}
/**
* Normalizes the vector (i.e. returns the unit vector in the same orientation as this vector)
*
* @return the unit vector
*/
public Vector normalize() {
float l = this.length();
float x = vals[I1] / l;
float y = vals[I2] / l;
float z = vals[I3] / l;
return new Vector(x, y, z);
}
/**
* Multiplies the vector by a scalar
*
* @param by the scalar to multiply by
* @return the result of the scalar multiplication
*/
public Vector multiply(float by) {
float x = vals[I1] * by;
float y = vals[I2] * by;
float z = vals[I3] * by;
return new Vector(x, y, z);
}
/**
* Computes the dot product of this vector with the specified vector
*
* @param with the vector to dot product this vector with
* @return the dot product
*/
public float dot(Vector with) {
return vals[I1] * with.vals[I1] + vals[I2] * with.vals[I2] + vals[I3] * with.vals[I3];
}
/**
* Computes the length of this vector
* <br>
* <b>Note:</b> If you are working with raw vectors from PDF, be careful -
* the Z axis will generally be set to 1. If you want to compute the
* length of a vector, subtract it from the origin first (this will set
* the Z axis to 0).
* <br>
* For example:
* <code>aVector.subtract(originVector).length();</code>
*
* @return the length of this vector
*/
public float length() {
return (float) Math.sqrt(lengthSquared());
}
/**
* Computes the length squared of this vector.
*
* The square of the length is less expensive to compute, and is often
* useful without taking the square root.
* <br><br>
* <b>Note:</b> See the important note under {@link Vector#length()}
*
* @return the square of the length of the vector
*/
public float lengthSquared() {
return vals[I1] * vals[I1] + vals[I2] * vals[I2] + vals[I3] * vals[I3];
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return vals[I1] + "," + vals[I2] + "," + vals[I3];
}
/**
* Calculates the hashcode using the values.
*/
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + Arrays.hashCode(vals);
return result;
}
/**
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
Vector other = (Vector) obj;
if (!Arrays.equals(vals, other.vals)) {
return false;
}
return true;
}
}