Android Open Source - 4est Vector

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License

The source code is released under:
MIT License
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Java Source Code

package com.wordsaretoys.rise.geometry;
/* w  w  w.ja v a  2s .  c o  m*/

/**
 * 
 * represents a vector in 3-space plus standard operations
 * 
 * @author chris
 *
 */
public class Vector {
  
  public float x;
  public float y;
  public float z;

  /**
   * constructor, set initial values
   * @param x, y, z initial values
   */
  public Vector(float x, float y, float z) {
    set(x,  y,  z);
  }
  
  public Vector() {
    set(0, 0, 0);
  }
  
  /**
   * set vector components
   * @param x, y, z components of the vector
   * @return self
   */
  public Vector set(float x, float y, float z) {
    this.x = x;
    this.y = y;
    this.z = z;
    return this;
  }
  
  /**
   * copy components of another vector
   * @param v, vector to copy from
   * @return self
   */
  public Vector copy(Vector v) { 
    x = v.x;
    y = v.y;
    z = v.z;
    return this;
  }

  /**
   * add another vector to this one
   * @param v, vector to add
   * @return self
   */
  public Vector add(Vector v) {
    x += v.x;
    y += v.y;
    z += v.z;
    return this;
  }
  
  /**
   * subtract another vector from this one
   * @param v, vector to subtract
   * @return self
   */
  public Vector sub(Vector v) {
    x -= v.x;
    y -= v.y;
    z -= v.z;
    return this;
  }
  
  /**
   * multiply this vector by a constant
   * @param c, constant to multiply
   * @return self
   */
  public Vector mul(float c) {
    x *= c;
    y *= c;
    z *= c;
    return this;
  }
  
  /**
   * divide this vector by a constant
   * return zero-length vector if constant equals zero
   * @param c, constant to divide by
   * @return self
   */
  public Vector div(float c) {
    if (c != 0) {
      x /= c;
      y /= c;
      z /= c;
    } else {
      set(0, 0, 0);
    }
    return this;
  }
  
  /**
   * generate additive inverse of the vector
   * @return self
   */
  public Vector neg() {
    return set(-this.x, -this.y, -this.z); 
  }
  
  /**
   * return length of the vector
   * @return length
   */
  public float length() {
    return (float) Math.sqrt(x * x + y * y + z * z);
  }
  
  /**
   * return distance between this vector and another
   * @param v vector
   * @return distance
   */
  public float distance(Vector v) {
    return (float) Math.sqrt(distsq(v));
  }
  
  /**
   * return square of distance between this vector and another
   * @param v vector
   * @return distance squared
   */
  public float distsq(Vector v) {
    float dx = x - v.x;
    float dy = y - v.y;
    float dz = z - v.z;
    return dx * dx + dy * dy + dz * dz;
  }
  
  /**
   * normalize this vector
   * @return self
   */
  public Vector norm() {
    float l = length();
    return div(l);
  }
  
  /**
   * return dot product between this vector and another
   * @param v vector
   * @return dot product
   */
  public float dot(Vector v) {
    return x * v.x + y * v.y + z * v.z;
  }
  
  /**
   * cross this vector with another
   * @param v vector
   * @return self
   */
  public Vector cross(Vector v) {
    float tx = x;
    float ty = y;
    float tz = z;
    x = ty * v.z - tz * v.y;
    y = tz * v.x - tx * v.z;
    z = tx * v.y - ty * v.x;
    return this;
  }
  
  /**
   * copy vector data to float array
   * @param a float array (size >= 3)
   * @return filled array [x, y, z]
   */
  public float[] toArray(float[] a) {
    a[0] = x;
    a[1] = y;
    a[2] = z;
    return a;
  }
  
  /**
   * round the vector components to the nearest n
   * @param n number to round by
   * @return self
   */
  public Vector nearest(float n) {
    x = (float) Math.round(x / n) * n;
    y = (float) Math.round(y / n) * n;
    z = (float) Math.round(z / n) * n;
    return this;
  }
  
  /**
   * transform vector by matrix multiplication
   * @param m 4x4 matrix laid out in 16-element array
   * @return self
   */
  public Vector transform(float[] m) {
    float mx = m[0] * x + m[4] * y + m[8] * z + m[12];
    float my = m[1] * x + m[5] * y + m[9] * z + m[13];
    float mz = m[2] * x + m[6] * y + m[10] * z + m[14];
    float d = m[3] * x + m[7] * y + m[11] * z + m[15];
    return this.set(mx / d, my / d, mz / d);
  }
  
  /**
   * generate a guaranteed perpendicular vector
   * for length > 0
   * @return self
   */
  public Vector perp() {
    float swp;
    if (x != y) {
      swp = x;
      x = y;
      y = swp;
    } else if (x != z) {
      swp = x;
      x = z;
      z = swp;
    } else {
      swp = y;
      y = z;
      z = swp;
    }
    if (x != 0) {
      x = -x;
    } else if (y != 0) {
      y = -y;
    } else {
      z = -z;
    }
    return this;
  }
  
}
Java Source Code List
