Difference between revisions of "U"

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This page is dedicated for describing the <code>xor.util.ds.U</code>
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{{Stub}}
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This page is dedicated for describing the <code>aaa.util.math.U</code>
  
  
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U is a universal immutable data-structure library, where U stands for both Util and Universal.
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''U'' is a universal math library, where ''U'' stands for ''U''niversal.  
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With U, you can write code just like this:
 
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<syntaxhighlight lang="java">
 
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Vec dis = displacement(bot.pos(), enemy.pos());
 
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dis = rotate(dis, radians(PI / 2));
 
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Point projected = project(bot.pos(), dis);
 
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</syntaxhighlight>
 
  
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Or even this:
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The purpose of U is to avoid code like this, which coupled business logic and math logic
  
 
<syntaxhighlight lang="java">
 
<syntaxhighlight lang="java">
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Direction direct = direction(displacement(bot.pos(), enemy.pos()));
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double absoluteBearing = this.getHeadingRadians() + event.getBearingRadians();
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double latVel = cross(direct, enemy.vel());
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double latVel = Math.sin(event.getHeadingRadians() - absoluteBearing) * event.getVelocity();
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double advVel = -dot(direct, enemy.vel());
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double advVel = -Math.cos(event.getHeadingRadians() - absoluteBearing) * event.getVelocity();
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</syntaxhighlight>
 
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And if you like:
 
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<syntaxhighlight lang="java">
 
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import xor.util.ds.*;
 
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import static xor.util.ds.U.*;
 
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class Wave {
 
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  private final double fireTime;
 
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  private final Point source;
 
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  private final Direction direction;
 
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  Wave(double fireTime, @NotNull Point source, @NotNull Direction direction) {
 
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    this.fireTime = fireTime;
 
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    this.source = source;
 
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    this.direction = direction;
 
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  }
 
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  public @NotNull Vec displacement(double now, double speed) {
 
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    return mul(direction, speed * (now - fireTime));
 
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  }
 
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}
 
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</syntaxhighlight>
 
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With a universal immutable data-structure library, you can easily build data abstraction on top.
 
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<strong>No longer messy code like this:</strong>
 
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<syntaxhighlight lang="java">
 
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@Override
 
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public final void onScannedRobot(@NotNull ScannedRobotEvent event) {
 
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  double absoluteBearing = this.getHeadingRadians() + event.getBearingRadians();
 
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  double latVel = Math.sin(event.getHeadingRadians() - absoluteBearing) * event.getVelocity();
 
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  double advVel = -Math.cos(event.getHeadingRadians() - absoluteBearing) * event.getVelocity();
 
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}
 
 
</syntaxhighlight>
 
</syntaxhighlight>
  
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<syntaxhighlight lang="java">
 
<syntaxhighlight lang="java">
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@Override
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V direction = direction(robot.pos(), enemy.pos());
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protected void onUpdated() {
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double latVel = cross(direction, enemy.vel());
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  Direction direct = direction(displacement(bot.pos(), enemy.pos()));
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double advVel = -dot(direction, enemy.vel());
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  double latVel = cross(direct, enemy.vel());
 
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  double advVel = -dot(direct, enemy.vel());
 
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}
 
 
</syntaxhighlight>
 
</syntaxhighlight>
  
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A side benefit of using U is that the need of massive trigs is automatically eliminated, as trigs are calculated only when retrieving data from robocode API.
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the second one is also much faster because it involves no trig.
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You can write PrecisePrediction even without using trigs!
 
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<syntaxhighlight lang="java">
 
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Point pos = bot.pos();
 
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Vec vel = bot.vel();
 
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Angle turn = bot.turnRate(); // trigs are pre-calculated.
 
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for (int i = 0; i < 100; ++i) {
 
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  vel = rotate(vel, turn); // rotate is done with only "*" and "+"
 
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  pos = project(pos, vel); // project is done with only "+"
 
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}
 
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</syntaxhighlight>
 

Latest revision as of 07:17, 8 August 2018

This article is a stub. You can help RoboWiki by expanding it.

This page is dedicated for describing the aaa.util.math.U



U is a universal math library, where U stands for Universal.

The purpose of U is to avoid code like this, which coupled business logic and math logic 

double absoluteBearing = this.getHeadingRadians() + event.getBearingRadians();
double latVel = Math.sin(event.getHeadingRadians() - absoluteBearing) * event.getVelocity();
double advVel = -Math.cos(event.getHeadingRadians() - absoluteBearing) * event.getVelocity();

write like this: 

V direction = direction(robot.pos(), enemy.pos());
double latVel = cross(direction, enemy.vel());
double advVel = -dot(direction, enemy.vel());

the second one is also much faster because it involves no trig.

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