# Talk:Historical Velocity Recall

That old page / code example was a bit long for what a simple idea this was, so I made a much simpler page / example and abstracted out the linear targeting part. --Voidious 04:15, 21 November 2007 (UTC)

Um... is this page supposed to be called Historical Velocity Recall, not Historical Velocity Recal? --`AaronR` 04:39, 21 November 2007 (UTC)

## From old wiki's Historical Velocity Recal page

This is a method of targeting I'm developing for BlueMind.

This method basicaly uses CircularTargeting, but instead of using the current enemy's velocity, you keep a log of all of its recorded velocities: and shooting at the "highest" point in the graph.

This is achieved throught the use of a vector and array pair.

### Implementation

```       static Vector velocityMap;

double[] vArray = new double[321];

Velocity enemyV = new Velocity(e.getVelocity());

for(int flush=0;flush<321;flush++){
vArray[flush]=0;
}

Velocity temp = new Velocity(0);
double temp2=0;
out.println(velocityMap.size());
for(int index=0; index < velocityMap.size(); index++){
temp = (Velocity)velocityMap.get(index);
temp2 = (temp.v+8)*20;
vArray[(int)temp2]++;
}

Count target = new Count();
for(int scan=0; scan < 321; scan++){
if(vArray[scan]>target.threshHold){
target.value = (scan/20)-8;
target.threshHold=vArray[scan];
}
}

double power = (2200/Math.pow(e.getDistance(),1.15));
if(power>=getEnergy()){
power = getEnergy()-.1;
}
if(power>3)
power=3;
if(power<.1)
power=.1;
double dist = e.getDistance();
double playerX = getX();
double playerY = getY();
double enemyX = playerX + (dist * Math.sin(bearing));
double enemyY = playerY + (dist * Math.cos(bearing));
double bulletV = 20 - 3 * power;
enemyH += (enemyH-lastH)/(getTime()-lastScanT);
double predictD = e.getDistance();
double predictX = enemyX;
double predictY = enemyY;
double rawV = target.value;
double theta = 0;
double time2 = 0;
double t=0;
double timeTheta = 0;
double time0=dist/bulletV;
int deltaT = 0;
int others = getOthers();
double lastDiff=Double.POSITIVE_INFINITY;
for(deltaT=-1000;deltaT<=1000;deltaT++){
t = time0 + deltaT;
predictX = enemyX+((rawV*t)*Math.sin(enemyH));
predictY = enemyY+((rawV*t)*Math.cos(enemyH));
if (predictX < 20){
predictX = 20;
}else if(predictX > battleFieldWidth-20){
predictX = battleFieldWidth-20;
}
if (predictY < 20){
predictY = 20;
}else if(predictY > battleFieldHeight-20){
predictY = battleFieldHeight-20;
}
predictD = Point2D.Double.distance(playerX,playerY,predictX,predictY);
timeTheta = Utils.absoluteBearing(playerX, playerY, predictX, predictY);
timeTheta = Utils.normalizeBearing(timeTheta - gunH);
time2 = (predictD / bulletV) + (timeTheta / 20);
if(Math.abs(t-time2) <= lastDiff){
theta = Utils.absoluteBearing(playerX, playerY, predictX, predictY);
theta = Utils.normalizeBearing(theta-gunH);
lastDiff = Math.abs(t-time2);
}
}
turnGunRight(Utils.normalizeBearing(theta));

lastH = enemyH;
lastScanT = getTime();

if(getEnergy()>0.2)
fire(power);
```

This sounds very similar to the aiming method that Stampede 1.3.3 currently uses (except it has both a linear and a circular version in a VG array). I have not been able to improve it much further than the gun currently in the RR; however that is probably due to my sloppy implementation rather than a weakness in the concept. I'm curious to see how you fare with this. --wcsv