Corona SDK Tutorial: Circle Objects

Make a Circle

To make a circle in Corona SDK we use the function newCircle of the display object. This function takes three parameters in this order.:

  • the x coordinate for the center
  • the y coordinate for the center
  • the circle’s radius

config.lua

First let’s make a config file to set the screen size.

application =
{
     content =
     {
        width = 320,
        height = 480,
        scale = "zoomEven"
      }
}

main.lua

Now lets work on the main.lua file. We can store the circle in a variable and use that variable later to change other properties of that circle like color for example.

Let’s make a circle called “circle_variable_name” with the center at (160,240) and a radius of 50.

--local nameofcircle = display.newCircle( x-cordinate, y-cordinate, radius )
local circle_variable_name = display.newCircle(160,240,50)
White circle on mobile application

The result from the code above

The default color of the circle is white, let’s change the color to red using the setFillColor function. The setFillColor function also needs three parameters which range from 0 to 250 in this order:

  • amount of red
  • amount of green
  • and amount of blue
--nameofcircle:setFillColor(Red,Green,Blue)
circle_variable_name:setFillColor(250, 0, 0)

The full code for the circle is this

local circle_variable_name = display.newCircle(160,240,50)
circle_variable_name:setFillColor(250, 0, 0)
red circle in phone application

the result from the code above

We can also add a stroke, and color to that stroke, to the circle just created with these two functions

--nameofcircle.strokeWidth = any_interger
circle_variable_name.strokeWidth = 3
--nameofcircle:setStrokeColor(Red,Green,Blue)
circle_variable_name:setStrokeColor(0,250,0)

The full code for the circle is

local circle_variable_name = display.newCircle(160,240,50)
circle_variable_name:setFillColor(250, 0, 0)
circle_variable_name.strokeWidth = 3
circle_variable_name:setStrokeColor(0,250,0)
Red Circle with Stroke

Red circle with green stroke

Now to create more than one circle you simply create different variable names like in the following example

local circle = display.newCircle(160,240,50)
circle:setFillColor(100,190,0)

local circle1 = display.newCircle(100,150,30)
circle1:setFillColor(100,90,190)

local circle2 = display.newCircle(160,400,90)
circle2:setFillColor(250,30,190)
Different colored circles on application

Different colored circles

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