diff options
Diffstat (limited to 'experimental/Intersection/LineIntersection.cpp')
| -rw-r--r-- | experimental/Intersection/LineIntersection.cpp | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/experimental/Intersection/LineIntersection.cpp b/experimental/Intersection/LineIntersection.cpp index ab23c442ce..5308a26474 100644 --- a/experimental/Intersection/LineIntersection.cpp +++ b/experimental/Intersection/LineIntersection.cpp @@ -9,12 +9,28 @@ #include "LineIntersection.h" #include <algorithm> // used for std::swap +/* Determine the intersection point of two lines. This assumes the lines are not parallel, + and that that the lines are infinite. + From http://en.wikipedia.org/wiki/Line-line_intersection + */ +void lineIntersect(const _Line& a, const _Line& b, _Point& p) { + double axLen = a[1].x - a[0].x; + double ayLen = a[1].y - a[0].y; + double bxLen = b[1].x - b[0].x; + double byLen = b[1].y - b[0].y; + double denom = byLen * axLen - ayLen * bxLen; + assert(denom); + double term1 = a[1].x * a[0].y - a[1].y * a[0].x; + double term2 = b[1].x * b[0].y - b[1].y * b[0].x; + p.x = (term1 * bxLen - axLen * term2) / denom; + p.y = (term1 * byLen - ayLen * term2) / denom; +} /* Determine the intersection point of two line segments Return FALSE if the lines don't intersect from: http://paulbourke.net/geometry/lineline2d/ -*/ + */ int intersect(const _Line& a, const _Line& b, double aRange[2], double bRange[2]) { double axLen = a[1].x - a[0].x; @@ -27,7 +43,7 @@ int intersect(const _Line& a, const _Line& b, double aRange[2], double bRange[2] byLen * axLen == ayLen * bxLen byLen * axLen - ayLen * bxLen == 0 ( == denom ) */ - double denom = byLen * axLen - ayLen * bxLen; + double denom = byLen * axLen - ayLen * bxLen; if (approximately_zero(denom)) { /* See if the axis intercepts match: ay - ax * ayLen / axLen == by - bx * ayLen / axLen |