Utils essentials

Shared Code
#41

While we’re on the topic of interpolation, he’s how I calculate height on a uniform grid, by splitting a quad into two triangles:


   public static final float interpolate2d(float x, float z, float nw, float ne, float se, float sw)
   {
      // n -= n % dim -> n = 0..dim (local offset)
      x = x - (int) x;
      z = z - (int) z;

      // Which triangle of quad (left | right)
      if (x > z)
         sw = nw + se - ne;
      else
         ne = se + nw - sw;

      // calculate interpolation of selected triangle
      float n = lerp(x, nw, ne);
      float s = lerp(x, sw, se);
      return lerp(z, n, s);
   }
#42 
public static String getStackTrace(){
	StringWriter sw = new StringWriter();
	new Throwable().printStackTrace(new PrintWriter(sw));
	return sw.toString();
}

public static void ultraHandySysoutJumpWithOneClickToTheCodeInEclipse(Object o){
	System.out.println(""+o+"\n--------------\n"+getStackTrace());
}

public static void main(String[] args){
	ultraHandySysoutJumpWithOneClickToTheCodeInEclipse("nice!");
}

This comes very handy in Eclipse - you can jump directly to the code, Eclipse formats the trace as links. This saved me a lot of time. Maybe shorten the method name to sysout or so.

#43

Thread.dumpStack() seems to work just fine :slight_smile:

#44

but… then it looks like an aggressive red error and you don’t have control in which order it prints (different threads). Try:

	for(int i=0;i<100;i++){
			Thread.dumpStack();
			System.out.println(""+i);
		}
#45

You mean you don’t print everything to stderr? ;D

#46

I use http://marian.musgit.com/grepconsole/index.html to colorize all errors in rainbow colors :wink:

#47

You can get similar kinds of curves by building on the perlin ease function, without the pesky trig functions.

#48

I don’t quite understand what this does. So you can click the line in the stack trace to jump to it? That seems to usually work for me already.

#49

He means it is printed to stdout as opposed to stderr

#50 

	public static float getXAtEndOfRotatedLineByOrigin(float x, float lineLength, float angle) {
		return x + (float) Math.cos(Math.toRadians(angle)) * lineLength;
	}

	public static float getYAtEndOfRotatedLineByOrigin(float y, float lineLength, float angle) {
		return y + (float) Math.sin(Math.toRadians(angle)) * lineLength;
	}
#51 

/**Lockup table for trigonometric functions (sinus and cosinus) used to improve performance
 * Singelton
 * @author Henning Brackmann
 */
public class TrigonometricLockupTable {
  private static TrigonometricLockupTable instance;
  private float[] sinustable_;
  private float[] cosinustable_;
  float precision=10;
  

  private TrigonometricLockupTable(){
    sinustable_ = new float[(int) (360*precision)];
    for (int i=0;i<sinustable_.length;i++){
      sinustable_[i]=(float)Math.sin(Math.toRadians(i/precision));
    }
    
    cosinustable_ = new float[(int) (360*precision)];
    for (int i=0;i<cosinustable_.length;i++){
      cosinustable_[i]=(float)Math.cos(Math.toRadians(i/precision));
    }
  }
  
  public static TrigonometricLockupTable getInstance(){
    if (instance==null){
      instance = new TrigonometricLockupTable();
    }
    return instance;
  }
  
  /**compute the sinus from lockup table
   * no range check 
   * @param aAngle Values between 0 and 359
   * @return sinus(aAngle)
   */
  public float sinus(float aAngle){
    return sinustable_[(int)(aAngle*precision)];
  }
  
  /**compute the cosinus from lockup table
   * no range check
   * @param aAngle Values between 0 and 359
   * @return cosinus(aAngle)
   */
  public float cosinus(float aAngle){
    return cosinustable_[(int)(aAngle*precision)];
  }
}
#52

Right… what about negative angles, or angles greater than a full rotation.

#53

no range check because i do the check at other places but it could be easyly added:


  /**correct a <0 or 359 degree overflow*/
  private float limitTo360(float angle){
    float resultangle=angle;
    if (resultangle>359) resultangle=resultangle%359;
    if (resultangle<0) resultangle=359-((-1*resultangle)%359);
    return resultangle;
  }

i dont undestand the SIN_MASK from your link. Its probably a smart trick but for now i am happy with my solution.

#54

359.5 degrees is not equivalent to 0.5 degrees, you should be using 360 in your limit calculations.

#55

a good point you are right.