creating circles and ovals programmatically Sin Cosin

[andyf2022 0]

Greetings coders,

 

Using Delphi 7, old I know but it is all I have.

 

I am wondering how to go about plotting a circle or an oval onto a canvas using code sin and cos, basically programmatically plotting points on the canvas around in a circle or oval of scroll bar selected sizes.

 

ideally with two scroll bars setting the the dimensions, then click a plot button, maybe using a timer to show that it is creating the shape a point at a time.

 

like to plot a

128x128

255x128

 

I am thinking in a 255x255 pixel area.

 

As I do this I want to save the plot points into an array with horizontal and Vertical values

 

Most of this I can figure but the sin cos functions and other math are beyond my experience.

 

 

 

 

 

 

 

 

 

 

 

 

[Vandrovnik 214]

You can find some inspiration here: https://www.mathsisfun.com/geometry/unit-circle.html

Sin and Cos in Delphi take argument in radians (not in degrees).

[Pat Foley 51]

20 minutes ago, Vandrovnik said:

Sin and Cos in Delphi take argument in radians (not in degrees).

Important to know. as is the unit circle!  

 

But let's not use theta or alpha Greek for angle today.

 

The first argument is x offset set it to Width div 2

Second argument is y offset set it to Height div 2

third and fourth arguments if the same draw a circle otherwise draws ellipse 

 Canvas.Ellipse(100,100,50,75);

[angusj 126]

https://github.com/AngusJohnson/Image32/blob/8cd56aa2bc2b4f007157b1c2f2fce451003152b0/source/Img32.Vector.pas#L2737

[andyf2022 0]

Thank you for the replies