On Thu, Jun 16, 2011 at 11:59 PM, Luc Maisonobe <[email protected]> wrote: > Le 16/06/2011 21:43, Curtis Jensen a écrit : >> >> On Wed, Jun 15, 2011 at 12:01 PM, Luc Maisonobe<[email protected]> >> wrote: >>> >>> Le 15/06/2011 19:57, Curtis Jensen a écrit : >>>> >>>> The Vector2D and Vector3D classes have dotProduct and crossProduct >>>> methods. I assume this is done be considering each vector originating >>> >>> There is no crossProduct in Vector2D in the current version I think. >>> >> >> You are correct. It was sloppy typing on my part to include >> crossProduct with Vector2D. >> >>>> from the origin. How can the dot product and cross products be >>>> calculated for vectors not centered at the origin? >>> >>> Yes, these methods are intended for vectorial spaces, not affine spaces, >>> which implies they work for vector centered at origin. >>> >>> We discussed on the dev list about having separate classes for >>> Affine/Vectorial spaces and finally decided to merge everything in only >>> one >>> class per dimension. This is a classical choice and the user often >>> already >>> know what his instances represent. >>> >> >> What is the suggested way of getting the dot and cross products for >> vectors not centered at the origin? ie. the dot product of a corner >> of a polygon. > > Something along these lines: > > Vector3D edge12 = vertex2.subtract(vertex1); > Vector3D egge23 = vertex3.subtract(vertex2); > double dot = edge12.dotProduct(edge23); >
Ah yes; thanks. -- Curtis > Luc > >> >> Thanks, >> Curtis >> >>> Luc >>> >>>> >>>> Thanks, >>>> Curtis --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
