I just wonder how can I determine if a given 3D point lies on a line given by 2 points, and ALSO it lies between those 2 points?
Share
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
I just wonder how can I determine if a given 3D point lies on a line given by 2 points, and ALSO it lies between those 2 points?
Points a,b,c are collinear (all lie on a single line) if b-a,c-a are parallel, which is true iff the cross product (b-a) x (c-a) is zero. (That is, all three of its components are zero. You should probably actually permit them to be nonzero but very very small; exactly what that should mean will depend on your application.)
Given that points a,b,c are collinear, b lies between a and c iff the scalar product (b-a).(c-b) is positive. (Non-negative, if it’s OK for b to be coincident with a or c.)