Thread: How are s&t calculated on a NURBS surface?

  1. #1
    Registered User
    Join Date
    Oct 2002
    Posts
    72

    How are s&t calculated on a NURBS surface?

    Don't know how many of you deal with NURBS surfaces, but....

    How are the s&t coordinates calculated on a NURBS surface? More specifically, are they related to the knots/isoparms?

    I'm attempting to assign texture corrdinates as point attributes to the CV's of a nurb, but if I refine the nurb by adding several isoparms between two of the original (making a thick concentration of isoparms in one section), then render with a shader that bases color on the uv values I calculated, the color change gets bunched up at the point of high concentration of isoparms. If I do the same test using s&t instead of my u&v, the color changes smooth across the surface.... So I'm guessing my calculation of u&v is not like the calculation of s&t - hence the question.

  2. #2
    Registered User
    Join Date
    Apr 2002
    Posts
    1,571
    I've only dealt with Total Degree Surfaces and Bi-Degree Surfaces. Of course I have dealt with B-Splines using de Boor algorithm. I don't know about NURBS surfaces but I may know someone who does. If I see him I will ask him and respond.

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Linked List Not Saving Value as Int
    By bar338 in forum C Programming
    Replies: 4
    Last Post: 05-04-2009, 07:53 PM
  2. OpenGL: How to make surface shiny
    By ting in forum Game Programming
    Replies: 6
    Last Post: 06-18-2008, 05:09 PM
  3. Another weird error
    By rwmarsh in forum Game Programming
    Replies: 4
    Last Post: 09-24-2006, 10:00 PM
  4. Please help with my game
    By jjj93421 in forum Game Programming
    Replies: 10
    Last Post: 04-12-2004, 11:38 PM
  5. Game update...
    By jdinger in forum Game Programming
    Replies: 14
    Last Post: 11-08-2002, 07:10 AM