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Author: KStor | Website: http://

The Routine (con't)

The drawing routine
This is the very core of the engine: the program that converts the 3D coordinates to 2D coordinates (as explained in The Math). In the fifth frame, draw, enter this:

  • Set Variable: "normalz" = depth * depth
    Normalz is the value k in the plane equation, depth being the z-coordinate of the normal vector of the view-plane (the plane being parallel to the xy plane, the vectors coordinates are (0,0,depth))
  • Set Variable: "n" = "1"
    Loop While (n<=totalpoints)
          Set Variable: "u" = (depth - eyez)/(eval("z"&n) - eyez)
          If (n<=9)
                Set Variable: "2Dx0"&n =  u * eval("x"&n) + centerx
                Set Variable: "2Dy0"&n =  u * eval("y"&n) + centery 
                Set Variable: "2Dx"&n =  u * eval("x"&n) + centerx
                Set Variable: "2Dy"&n =  u * eval("y"&n) + centery 
          End If
          Set Variable: "n" = n + 1
    End Loop
    This part is a bit more complicated. We actually convert the 3D coordinates to 2D coordinates. For each point, we first calculate the value u as explained in The Math. Then we recalculate the 2D coordinates by multiplying the 3d coordinates by u. I can't explain exactly what I've done here but if you study the math link I gave you should be able to understand it.
  • Set Variable: "n" = "1"
    Loop While (n<=totallines)
          Duplicate Movie Clip ("/baseline", "line" & n, n)
          Call ("drawline")
          Set Variable: "n" = n + 1
    End Loop
    Finally we just draw the the lines by duplicating the basic movie clip and calling the drawline frame.
Ok, now your 3D engine is basically finished. But we also want a zoom and rotations. That's easy, follow the guide!

» Level Advanced

Added: 2000-12-04
Rating: 9 Votes: 2631
(10 being the highest)
» Author
KStor is a student living in France and working with Flash during his free time...that is, not very much.
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Download the files used in this tutorial.
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