opengl spot_cutoff > 90 invalid?


    May 22 2006 | 4:31 pm
    "spot_cutoff" values between 90 and 180 are triggering error messages. I'd like to morph from 360 positional lighting to spotlights, but I can't.
    using jitter 1.5.2 I get: ob3d_draw_end popmatrix: GL Error: Invalid value.
    180 or 90 (and below) is fine with Jitter, but everything in between is invalid.
    Is this not accepted by OpenGL standards or is it a possible Jitter bug?
    -thijs

    • May 22 2006 | 4:40 pm
      Sounds like it might be a good idea to mention again that the standard OpenGL stuff is available online for you at http://www.opengl.org/ . It's a great resource.
    • May 22 2006 | 5:56 pm
      From the Red Book (p.~189):
      "To specify the angle between the axis of the cone an a ray along the edge of the cone, use the GL_SPOT_CUTOFF parameter....By default, the spotlight feature is disabled because the GL_SPOT_CUTOFF parameter is 180.0. This value means that light is emitted in all directions (the angle at the cone's apex is 360 degrees,so it isn't a cone at all). The value for GL_SPOT_CUTOFF is restricted to the range [0.0 90.0] (unless it has the special value 180.)."
      Andrew B.
    • May 22 2006 | 7:19 pm
      Ah, thanks. Sorry for the wasted time and bandwidth. I must have overlooked it.
      -thijs