CODEWITHSUNDEEP
java
bleh
bleh

Reputation: 125

How can I fix these multiple problems that deal with slope?

I want to make a little piece of code that makes and ellipse go toward another point.

The principle is simple enough:

int ellipseX = 30;
int ellipseY = 30;
int ellipse1X = MouseInfo.getPointerInfo().getLocation().x;
int ellipse1Y = MouseInfo.getPointerInfo().getLocation().y;
//m=(y2-y1)/(x2-x1)
double slopex = ellipse1X/ellipseX;
double slopey = ellipse1Y/ellipseY;
public void paintComponent(Graphics g){
    g.fillOval(ellipseX, ellipseY, 4, 4);
    ellipseX+=slopex;
    ellipseY+=slopey;
    repaint();
}

Now there are a couple of problems with that-

And a whole bunch of problems besides. How can I fix this?

Upvotes: 0

Views: 39

Answers (3)

Pooya
Pooya

Reputation: 6126

There is a little trick in dividing two integers when you expect a double as the return type. You need to explicitly cast the numbers to double before performing the division. here is a quick fix to that I also changed the data types for ellipseX and ellipseY to double:

double ellipseX = 30;
double ellipseY = 30;
int ellipse1X = MouseInfo.getPointerInfo().getLocation().x;
int ellipse1Y = MouseInfo.getPointerInfo().getLocation().y;
//m=(y2-y1)/(x2-x1)
double slopex = (double)ellipse1X/ellipseX;
double slopey = (double)ellipse1Y/ellipseY;
public void paintComponent(Graphics g){
    g.fillOval((int)ellipseX, (int)ellipseY, 4, 4);
    ellipseX+=slopex;
    ellipseY+=slopey;
    repaint();
}

Upvotes: 2

gpasch
gpasch

Reputation: 2682

if you want the slope to follow your mouse pointer then you incorporate inside the loop - I dont know what slope will give you and I'm not sure the equations are right - just answering your this question - also see for int+double

int ellipseX = 30;
int ellipseY = 30;
int ellipse1X = MouseInfo.getPointerInfo().getLocation().x;
int ellipse1Y = MouseInfo.getPointerInfo().getLocation().y;
  double slopex = ellipse1X/ellipseX;
  double slopey = ellipse1Y/ellipseY;
while(true) {
  ellipse1X = MouseInfo.getPointerInfo().getLocation().x;
  ellipse1Y = MouseInfo.getPointerInfo().getLocation().y;
  slopex = ellipse1X/ellipseX;
  slopey = ellipse1Y/ellipseY;
  ellipseX=(int)Math.rint(ellipseX+slopex);
  ellipseY=(int)Math.rint(ellipseY+slopey);
  repaint()
}

public void paintComponent(Graphics g){
    g.fillOval(ellipseX, ellipseY, 4, 4);
}

repaint should not be generally called within paint()

Upvotes: 0

Debosmit Ray
Debosmit Ray

Reputation: 5403

The first issue I can see in the code is that you are storing the result of dividing 2 integer variables into a double. If you check, the double will contain a whole number value. Instead, you should do something along the lines of,

double myDouble = (numerator * 1.0) / denominator;

Upvotes: 0

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