• In canvas.js there is the Frustum function.
  • This is just an implementation of glFrustum
• I always have problems getting this adjusted as I want it.
  • So I continued to build my simple interface.
  • BTW, I seem to have a visible surface problem too.
• The view starts at
  • Look at (0,0,0)
  • Eye at (0,1.3, -3.6)
  • Near = 1.8
  • Far is 20, this really doesn't matter as long as it is "far" enough.
  • Left and right are +/- 3
  • Top is 3, bottom is -1
• I added member functions to the canvas to change many of these values.
• I added choices to the menu to change many of these as well.
• Anything you need clarified here?

Field Of View

• A second way to specify the frustum is the fov command.
  • This takes an angle between the top and the bottom of the screen
  • (stolen image)
  • The second argument is the aspect ratio between width and height
    • 1 means width = height.
    • less than 1 means width > height.
    • Greater than means the other way.
  • The third and fourth arguments are the near and far plane.
  • This is really just another way to specify a frustum.
  • And there is a function in MV.js
• By the way, the two matrices are slightly different
  • Frustum is the generic case where you don't have to be symmetric
    • left ≠ -right
    • top ≠ -bottom
  • For FOV these hold, as you only specify angles.
  • So look at the two derived matrices on 255 and 256 if you really care about this.