Hi,

I have been trying to draw circles in Tiny Basic using the line command.

Can someone please share a small basic program I can use as a reference ?

Thanks

## Trying to draw circles in basic.

**Forum rules**

Be nice.

### Re: Trying to draw circles in basic.

This is based on Bresenham's algorithm:

I wonder how fast a Commodore 64 can do this in BASIC...

Code: Select all

```
'Draw filled circle with
'LINE statements
10 x=80:y=60:u=45:'Radius
20 cls:v=0:w=0
30 at x-u,y-v:line u+u,0
40 at x-u,y+v:line u+u,0
50 w=w+v+v+1:v=v+1
60 if w<0 goto 30
70 w=w-u-u+1:u=u-1
80 if u>0 goto 60
```

### Re: Trying to draw circles in basic.

Thanks, thats great.

I have made a colourful pattern.

5 poke 42,0:cls

6 a=61

7 a=a-1

8 poke 43,a

10 x=80:y=60:u=a

20 v=0:w=0

30 at x-u,y-v:line u+u,0

40 at x-u,y+v:line u+u,0

50 w=w+v+v+1:v=v+1

60 if w<0 goto 30

70 w=w-u-u+1:u=u-1

80 if u>0 goto 60

85 if a<2 goto 85

90 goto 7

Is there a way of drawing an empty circle ?

Thanks

I have made a colourful pattern.

5 poke 42,0:cls

6 a=61

7 a=a-1

8 poke 43,a

10 x=80:y=60:u=a

20 v=0:w=0

30 at x-u,y-v:line u+u,0

40 at x-u,y+v:line u+u,0

50 w=w+v+v+1:v=v+1

60 if w<0 goto 30

70 w=w-u-u+1:u=u-1

80 if u>0 goto 60

85 if a<2 goto 85

90 goto 7

Is there a way of drawing an empty circle ?

Thanks

### Re: Trying to draw circles in basic.

Thanks for sharing

Wikipedia has a lot of background: https://en.wikipedia.org/wiki/Midpoint_circle_algorithm

You can use the same algorithm and plot pixels instead of drawing lines, I suppose. I haven't tried.

Wikipedia has a lot of background: https://en.wikipedia.org/wiki/Midpoint_circle_algorithm