3D Math - How accurate should a circle be?
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Revision as of 13:25, 1 September 2010 by SteveBaker (Talk | contribs)
If you want to draw an accurate circle using straight lines - how many do you need?
Assuming you'd like your line to lie within one pixel of the true edge, then the largest radius you can draw with an N-sided polygon is:
R = 1 / (1 - cos ( PI / numSides ))
- 3 sides 2 radius
- 4 sides 3 radius
- 5 sides 5 radius
- 6 sides 7 radius
- 7 sides 10 radius
- 8 sides 13 radius
- 9 sides 17 radius
- 10 sides 20 radius
- 11 sides 25 radius
- 12 sides 29 radius
- 13 sides 34 radius
- 14 sides 40 radius
- 15 sides 46 radius
- 16 sides 52 radius
- 17 sides 59 radius
- 18 sides 66 radius
- 19 sides 73 radius
- 20 sides 81 radius
- 21 sides 90 radius
- 22 sides 98 radius
- 23 sides 107 radius
- 24 sides 117 radius
- 25 sides 127 radius
- 26 sides 137 radius
- 27 sides 148 radius
- 28 sides 159 radius
- 29 sides 171 radius
- 30 sides 183 radius
- 40 sides 324 radius
- 50 sides 507 radius
- 60 sides 730 radius
- 70 sides 993 radius
- 80 sides 1300 radius
- 90 sides 1600 radius
- 100 sides 2000 radius
- 120 sides 2900 radius
- 140 sides 4000 radius
- 160 sides 5200 radius
- 180 sides 6600 radius
- 200 sides 8100 radius
- 220 sides 9800 radius
- 240 sides 11700 radius
- 255 sides 13200 radius