Question

Im trying to get a rectangle to move from a fixed location, to a click point in my game. I have it working to the point that im getting good coordinates from the e.getX and e.getY methods in the mouse listener class. I also have the rectangle moving in straight lines to the side or up and down by increasing and decreasing the positionX and Y values but i need a way to move it to any point that i click on, basically i need to set the change in x and y. The way i was thinking is to compute the rise and run of the line from the click points and the start point and then set the x and y values to the rise and run. If i do it this way, i need a way to decrease the rise and run values down to their lowest terms so it moves fluidly. Or if there is a way im not thinking of that you can offer any guidence that would be helpfull.

Answer 1

How are you drawing it at the moment? Below is a method I used to shoot bullets in a little game that I made/really should finish sometime.

This is by no means all the code you will need, and in some places there are better ways to do things (which I’m sure people will start to tell me in the comments section after 🙂 ) but it should give you a basis to work from.

The one thing missing from this is regulating the speed at which it repaints (fps), sorry but I can’t remember the simple way to do this right now (need to get back to my actual job!) Hope it helps.

The barebones of it will be something like this:

//these set out the current position of your rectangle
double recX, reYy, recH, recW;

//this gives something to manage speed
int speed;

public void paintComponent(Graphics g) {
    g.drawRectangle(recX,rexY,recH,recW);
}

//here we work out the movement
public void clickedScreen(double x, double y){
    double newX = x;
    double newY = y;
    //calculate the speed to move at
    vX = newX - recX;
    vY = newY - recY;
    //get the distance
    length = Math.sqrt((v1*v1)+(v2*v2));
    //make it a unit vector
    v1 = v1/length;
    v2 = v2/length;
}

public moveRec(){
    recX = recX+(v1*speed);
recY = recY+(v2*speed);
}

while(true) {
    moveRec();
    repaint();
}