Remove a rectangle when a circle overlapps it

Programming Questions

Alex Pilk..

Remove a rectangle when a circle overlapps it

in Programming Questions • 9 months ago

Hi, guys. I'm new to Processing. I use it to communicate with Arduino and receive messages from serial port.

So I want to make a simple game that responds to buttons on arduino. I know only basic syntax and possibilities of Processing so it's hard for me to do simple things.

And now i'm stuck trying to remove a rectangle when a circle collides with it.

So here is part of my code I'm having problems with

import processing.serial.*;
Serial port;
int X = 250;
int Y = 250;
int px,py;
int PlayerRS=X+50;
int PlayerLS=X;
int PlayerT=Y;
int PlayerB=Y+50;
void setup()
{
size(500,500);
port = new Serial(this, "COM11", 9600);
port.bufferUntil('\n');
rectMode(CENTER);
background(255);
smooth();
px=250;
}
void draw()
{
background(0);
//You
rect(X,Y,50,50);
enemies();
}
void enemies(){
py=py+4/2;
ellipse(px, py, 15, 15);
if(px>=PlayerLS || px<=PlayerRS || py>PlayerT || py<PlayerB){
//And here I need that rectangle to be removed
}
}

Replies(2)

tgptialves

Re: Remove a rectangle when a circle overlapps it

9 months ago

Hello,

I did not look at your code because I don't understand why you need that or the it purpose.

If you want to know when the circle collides with the rectangle you need to know a few things first:

Is the circle and rectangle center the same? If yes, it is more simple to know the collision.

Either ways you have to work with Math. You have 4 points of the rectangle, so you can always define all the 4 lines equations of the rectangle. You can also define the circle equation, so you can always make a test if any of the 4 lines touches the circle.

I can help you with that, but first you need to explain yourself better.

I remembered an easier way if you only draw that rectangle and the circle:

Just before you draw the circle, with a for circle, teste every pixel that would be draw by the circle if it's already black (or wahtever color):

PImage test = get();
boolean touched=false; //Circle has not yet touched the rectangle
for(int x=0;x<15;x++) //where 15 is the circle radius
for(int y=0;y<15;y++) //the same, 15 is the circle radius
if((int)Math.sqrt(Math.pow(x,2)+Math.pow(y,2))==15) //if distance between selected pixel and center of the circle is equal to radius
{
if(test.pixels[x + y*width]==color(255))//If the rectangle was drawn in white and touches the circle
{
touched=true;
break;
}
}
if(!touched)
{
//draw the circle
}

The idea is to select the circle with a square and test if any pixel that was going to be draw by the circle is already drawn.

This technique is really simple, and it only requires that you draw the rectangle with a different color from the rest that was drawn before it.

Any questions, just reply.

Alex Pilk..

Re: Remove a rectangle when a circle overlapps it

9 months ago

Thanks for response)) I tried to figure out your code, but I placed it in my project and got an error. Well, never mind)) I guess I should learn more about processing first and then I'll get it. I'm just trying to communicate with Arduino using Processing, and I even made a successful project:

http://www.youtube.com/watch?v=t5W1jbOaUWs

Maybe you know some tutorial series, or a book that would help me improve my very basic Processing skills.

(And yes, I know there are some on their site. Just don't know if that's enough)))