| Revision: | 1.1 |
| Committed: | Sat Feb 22 02:07:21 2003 UTC (21 years, 2 months ago) by greg |
| Branch: | MAIN |
| CVS Tags: | rad5R2, rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R5, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1 |
| Log Message: | Changes and check-in for 3.5 release Includes new source files and modifications not recorded for many years See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release |
| # | User | Rev | Content |
|---|---|---|---|
| 1 | greg | 1.1 | { |
| 2 | Calculate center and radius of circle based on three | ||
| 3 | points in the plane. | ||
| 4 | |||
| 5 | Beware colinear points and points parallel to y-axis. | ||
| 6 | |||
| 7 | 6/4/2002 Greg Ward | ||
| 8 | solution due to Paul Bourke | ||
| 9 | |||
| 10 | Inputs: | ||
| 11 | |||
| 12 | x1,y1,x2,y2,x3,y3 - points on circle | ||
| 13 | |||
| 14 | Outputs: | ||
| 15 | |||
| 16 | xc, yc, r - center and radius | ||
| 17 | } | ||
| 18 | sq(x) : x*x; | ||
| 19 | |||
| 20 | ma = (y2-y1)/(x2-x1); | ||
| 21 | mb = (y3-y2)/(x3-x2); | ||
| 22 | |||
| 23 | xc = (ma*mb*(y1-y3) + mb*(x1+x2) - ma*(x2+x3)) / (2*(mb-ma)); | ||
| 24 | |||
| 25 | yc = ((x1+x2)/2 - xc)/ma + (y1+y2)/2; | ||
| 26 | |||
| 27 | r = sqrt(sq(x2-xc) + sq(y2-yc)); |