This code has been declared by its author to be Public Domain code.
Download source code | | Get Area Of Circle by Polarix | March |
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| Returns the area of an oval. |
Graphics 640,480
SetBuffer BackBuffer()
Global xpos = 320
Global ypos = 240
Global size# = 100
Global radius# = size/2
While Not KeyHit(1)
Cls
Oval xpos,ypos,size,size
Text 0,0,"The area of the circle is "+GetCircleArea(radius#)+" pixels"
Flip
Wend
End
Function GetCircleArea(r#)
Return(r#*r#*Pi)
End Function |
Comments |
Oops. My bad, thanks for telling me!
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No need to pass x and y to the function since they never get used
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Is Pi a defined constant in blitz. .. i didnt think it was....this will return zero
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Also the function will only return an integer.
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Pi is defined as 3.14159 in Blitz3D.
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| Also the function will only return an integer.
Pixels cannot be halfed or cut into smaller bits. so it will always be a whole number of pixels.
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| Is Pi a defined constant in blitz. .. i didnt think it was....this will return zero
I checked the example. It works fine for me.
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You're right, pixels are always at integral coordinates.
Still, in some cases it's useful to work with floating point coordinates because then you have sub-pixel coverage: a graphic covers "part" of the pixel, so the pixel is semitransparent. This is how some software do antialiased graphics.
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| Pixels cannot be halfed or cut into smaller bits. so it will always be a whole number of pixels.
The point of the comment about the function returning an integer is that it computes a floating point value but returns an integer.
The fact that the number of pixels is an integer is not really relevant. GetCircleArea is not counting pixels and will match the number of pixels drawn only by coincidence.
For example, with width = height = 8 GetCircleArea returns 50 when the actual number of pixels is 52.
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I don't get what you are saying, it works fine
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