Detect If User Clicks Inside a Circle

Detect if user clicks inside a circle

A circle, is the geometric position of all the points whose distance from a central point is equal to some number "R".

You want to find the points whose distance is less than or equal to that "R", our radius.

The distance equation in 2d euclidean space is d(p1,p2) = root((p1.x-p2.x)^2 + (p1.y-p2.y)^2).

Check if the distance between your p and the center of the circle is less than the radius.

Let's say I have a circle with radius r and center at position (x0,y0) and a point (x1,y1) and I want to check if that point is in the circle or not.

I'd need to check if d((x0,y0),(x1,y1)) < r which translates to:

Math.sqrt((x1-x0)*(x1-x0) + (y1-y0)*(y1-y0)) < r

In JavaScript.

Now you know all these values (x0,y0) being bubble.x and bubble.y and (x1,y1) being x and y.

How to detect whether or not user is clicking inside Circle in python graphics window

You already have the centre and radius of each Circle, you could write a function to determine whether a given Point is within that as follows:

from math import sqrt

def is_within(point, circle):
    distance = sqrt(((point.x - circle.x) ** 2) + 
                    ((point.y - circle.y) ** 2))
    return distance < circle.radius

Note that you will have to tweak the attribute names according to the graphics library you are using.

Canvas circle detect click position

Check out source of jPlayer circle demo.
You can use the same approach to get percentage:

var x = e.pageX - canvas.offsetLeft - w/2,
    y = e.pageY - canvas.offsetTop - h/2,
    mAngle = Math.atan2(y, x);

if (mAngle > -1 * Math.PI && mAngle < -0.5 * Math.PI) {
    mAngle = 2 * Math.PI + mAngle;
}

var percentage = (mAngle + Math.PI / 2) / 2 * Math.PI * 10;

demo: http://jsfiddle.net/7RUt3/

How do I check to see if a mouse click is within a circle in pygame?

Use the distance formula:

################################################################################
# Imports ######################################################################
################################################################################

from pygame.locals import *
import pygame, sys, math

################################################################################
# Screen Setup #################################################################
################################################################################

pygame.init()
scr = pygame.display.set_mode((640, 480))
pygame.display.set_caption('Box Test')

################################################################################
# Game Loop ####################################################################
################################################################################

while True:
    pygame.display.update(); scr.fill((200, 200, 255))
    pygame.draw.circle(scr, (0, 0, 0), (400, 300), 100)

    x = pygame.mouse.get_pos()[0]
    y = pygame.mouse.get_pos()[1]

    sqx = (x - 400)**2
    sqy = (y - 300)**2

    if math.sqrt(sqx + sqy) < 100:
        print 'inside'

    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

################################################################################
################################################################################
################################################################################

Getting the circle position on where the user clicks?

Your draw_circle function is doing two separate things, so I'm not sure it makes sense to keep it as a single function. It's not updating the circle's x and y coordinates correctly because you're always returning random coordinates even when you should be returning the moved circle's coordinates. I've broken out the two parts of that function into the main circle_game function in my code below.

I've replaced your check for a click inside a square with a check for a click inside a circle: (mouse.x - circle_x ) ** 2 + (mouse.y - circle_y) ** 2 <= CIRCLE_RADIUS_SQUARED.

I also have no idea what totalClicks += random.randint(0,5) was trying to achieve.

import random

from graphics import *

def circle_game():
    CANVAS_WIDTH = 600
    CANVAS_HEIGHT = 600
    CIRCLE_RADIUS = 50
    CIRCLE_RADIUS_SQUARED = CIRCLE_RADIUS * CIRCLE_RADIUS

    window = GraphWin("Click circles", CANVAS_WIDTH, CANVAS_HEIGHT)

    # Draw circle at random location to start game
    circle_x = random.randint(0, CANVAS_WIDTH)
    circle_y = random.randint(0, CANVAS_HEIGHT)
    circle_point = Point(circle_x, circle_y)
    circle = Circle(circle_point, CIRCLE_RADIUS)
    circle.setFill(color_rgb(200, 0, 0))
    circle.draw(window)

    total_clicks = 0
    inside_clicks = 0
    while total_clicks < 10 and inside_clicks < 3:
        mouse = window.getMouse()
        total_clicks += 1
        if (mouse.x - circle_x ) ** 2 + (mouse.y - circle_y) ** 2 <= CIRCLE_RADIUS_SQUARED:
            # Click was inside circle so we don't move circle
            inside_clicks +=1
        else:
            # Click was not inside circle so we move circle to mouse location
            dx = mouse.x - circle_x
            dy = mouse.y - circle_y
            circle.move(dx, dy)
            circle_x += dx
            circle_y += dy

if __name__ == '__main__':
    circle_game()

Detect mouse click on circle that is on different surface

You have to compute the mouse position relative to the Surface.

You have 2 possibilities. Either subtract the (top left) position of the Surface on the screen from the mouse position:

x = event.pos[0] - s_rect.left
y = event.pos[1] - s_rect.top

Or add the (top left) position of the Surface on the screen to the center point of the circle:

sqx = (x - (s_rect.left + 20))**2
sqy = (y - (s_rect.top + 20))**2

---

Complete example

from pygame.locals import *
import pygame, math

pygame.init()
screen = pygame.display.set_mode((640, 480))

s = pygame.Surface((100, 100))
s.fill((255, 0, 0))
s_rect = s.get_rect(center = (300, 300))
clicked = False

running = True
while running:
    for event in pygame.event.get():
        if event.type == QUIT:
            running = False
        if event.type == pygame.MOUSEBUTTONDOWN:
            
            x = event.pos[0]
            y = event.pos[1]

            sqx = (x - (s_rect.left + 20))**2
            sqy = (y - (s_rect.top + 20))**2

            if math.sqrt(sqx + sqy) < 20:
                clicked = not clicked
                print ('inside')

    screen.fill((200, 200, 255))
    color = (255, 255, 255) if clicked else (0, 0, 0)
    pygame.draw.circle(s, color, (20, 20), 20)
    screen.blit(s, s_rect)
    pygame.display.update()
    
pygame.quit()

Detect if an circle is clicked in pygame?

You need to calculate the Euclidean distance between the center of the circle and the mouse. Test if this distance is less than the radius:

def clicked(self):
    mouse_x, mouse_y = pygame.mouse.get_pos()
    dx = mouse_x - self.circle_x
    dy = mouse_y - self.circle_y
    distance = math.sqrt(dx*dx + dy*dy)  # or: distance = math.hypot(dx, dy)
    return distance <= self.circle_radius

You can improve performance and get rid of the costly math.sqrt operation by comparing the square of the distance to the square of the radius:

def clicked(self):
    mouse_x, mouse_y = pygame.mouse.get_pos()
    dx = mouse_x - self.circle_x
    dy = mouse_y - self.circle_y
    return dx*dx + dy*dy <= self.circle_radius*self.circle_radius

---

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