CODEWITHSUNDEEP
javamath
user8894938
user8894938

Reputation:

How to get (x,y) of circle surface?

I'm trying to draw line over all circle surface, my current shape look like:

enter image description here

My wrong attempt:

    for (int i = 0; i < 24; i++) {
        g.drawLine(xCenter - clockRadius + i , yCenter - clockRadius + i, xCenter - clockRadius + i + 5,
                yCenter - clockRadius + i + 5);
    }

I'm trying to draw a full clock :

enter image description here

Upvotes: 1

Views: 363

Answers (3)

user6490462
user6490462

Reputation:

You need to calculate points over 360 degree not just 24, so you have the radius and angel rotation (angel rotation from 0 to 360) to get the proper point of (x,y) we need to multiply sin or cos of angel with radius.

enter image description here

for (int i = 0; i < 360; i++) {
        int x = (int) (clockRadius * Math.cos(i)) + xCenter;
        int y = (int) (clockRadius * Math.sin(i)) + yCenter;
        g.drawLine(x, y, x + 5, y + 5);
    }

Note: for better result you may need to develop two loops, one for right (180) part and another for left (180) part.

Edit: to get the right direction you need to check for angel e.g:

int xV = 0, yV = 0;
if (i <= 90){
   xV = 5;
   yV = 5;
 }

Upvotes: 0

MBo
MBo

Reputation: 80127

I suspect that you want to draw small segments - ticks, centered at circumference and directed from the circle center. In this case use trigonometry alike hour hands drawing.

for (int i = 0; i < 24; i++) {
   double ang = i * Math.Pi / 12;
   g.drawLine((int) (xCenter + (clockRadius - 5) * Math.Cos(ang)), 
             (int) (yCenter + (clockRadius - 5) * Math.Sin(ang)), 
             (int) (xCenter + (clockRadius + 5) * Math.Cos(ang)), 
             (int) (yCenter + (clockRadius + 5) * Math.Sin(ang))); 
}

Upvotes: 1

Max Vollmer
Max Vollmer

Reputation: 8598

You are looking for cosinus and sinus.

circle with cos and sin

Your clock is a circle, and you can easily translate your steps into degrees on that circle. If you want to have 24 steps, 12 would be 180° (or π) and 24 would be 360°, or 2π. So to get the correct angles for each index, just devide 2π (360°) by 24 and multiply it by the current index. Then feed that resulting angle to the cos and sin functions, which give you the x and y coordinates respectively:

double x = Math.cos(2 * Math.PI / 24 * i);
double y = Math.sin(2 * Math.PI / 24 * i);

Of course you can optimize the 2 and the 24 into one constant that you define somewhere and then use in your code.

Upvotes: 3

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