Jump to content
  • Advertisement
Sign in to follow this  
ferhua

dot product problem in calculating reflective vector

This topic is 640 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

[attachment=33625:1.PNG]

The vector I and n are given, n is the unit vector, the output is vector r.

my question is the orientation of dot(n,l)*n.

Since dot(n,l) is the signed length(negative in this case)

why "the vector below n" still need to multiply by "n" ,  and why the vector dot(n,l)*n and "n" have opposite orientations.(assume that "dot(n,l)" is a scalar,after it multiply by "n", it should have the same direction as "n" )

[attachment=33626:??.PNG]

In my opinion ,it should be

[attachment=33627:??1q.PNG]

Share this post


Link to post
Share on other sites
Advertisement

why "the vector below n" still need to multiply by "n" ,  and why the vector dot(n,l)*n and "n" have opposite orientations.(assume that "dot(n,l)" is a scalar,after it multiply by "n", it should have the same direction as "n" )


You need to multiply by n to have a vector. Remember that the dot product is just a number (negative in this case, as you pointed out).

dot(n,l)*n and n point in opposite directions because dot(n,l) is negative. Negative scalars do that.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!