## Math for VSFX

Updated on Feb 13  2017

• Examples

# Deborah R. Fowler

## Dot Product

Posted before Nov 12   2013
updated May 28  2016

"Dot Product
is the product of the magnitudes of the two vectors and the cosine of the angle between them. The name "dot product" is derived from the centered dot$\cdot$ " that is often used to designate this operation."  See wiki entry. See the hip file for a demonstration.

Here is an excellent application using the dot product, pythagorean theorem and a little bit of vector math tossed in to solve an animation problem.

Two point constraint problem pdf. Sample hip file here. (example not at origin here).

Additionally, after you look at the first formulation of the solution, look at the topsy turvy example.

Two point constraint problem continued pdf. Sample hip file here.

May 24/2014 - added a flipped version of the top most two constraint version with an additional pdf and hip (READ the FIRST PDF FIRST)

March 7/2015 - going one step further added a mirrored version of the above with the other point also moving (hip here)

May 25/2016 - combine the above constraints - remember, as long as you know where the two points are at any given time you can use them to create something like this https://www.youtube.com/watch?v=pKrHTYqm8pw

Proxy hip given for basic technique guidelines
.

May 28/2016 - animating the two point constraints - this one also takes into account crossing over two quadrants

I have created a hip example file which demonstrates add nodes/two point constraints. Remember that points render as spheres so you may want to blast your add points before rendering.