Taxiline creation with GMax

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The following tutorial is made by Jeffrey Stähli. This tutorial can also be found in the scenery forum, but it deserves a place in Wiki. The technique used is very nice to create smooth taxi lines with custom textures.

Loft Method

A loft is normally a two-dimensional cross section extruded along a 3rd dimension to produce a 3 dimensional object.

The 2-D polygon is a spline that is called Shape in GMAX , and the 1-D line defining the path is another spline called Path.

This method creates a rectangular cross-section spline but then (a) cuts off the bottom and sides of the rectangle, leaving a 1 dimensional template entity "top" which (b) is then moved to a 0.000 meter altitude.

The surface entity template is still extrudable along the curvilinear path leaving a finite-width zero-depth bit-mappable taxiway (or any other image) on the surface.

Create a taxiway line template (spline)

  1. in the "Create" menu, choose "Shapes".
  2. select Rectangle
  3. draw one in the FRONT viewport (size doesn't matter now)

    Taxilines gmax 01.jpg

  4. adjust the size of your rectangle. The important size is the WIDTH of your taxiway line.
  5. center your rectangle to (0,0,0)!

    Taxilines gmax 02.jpg

  6. convert the rectangle to a "Editable Spline" and turn on "Segment" selection.
  7. select the indicated 3 segments and delete them.

    Taxilines gmax 03.jpg

  8. now, set the top segment to ground level 0.0m. Template is done. (You may rename it to "TWYLINE_TEMPLATE" or so for the next steps)

    Taxilines gmax 04.jpg

  9. create your taxiline "guides" using splines. For straight lines, just use "line" and for bends, the "arc" object is perfect. Don't connect the splines to a network, just leave them as single objects. The Loft method doesn't seem to work with spline-networks. Your transitions should be more exact than my quick try.

    Taxilines gmax 05.jpg

Now the fun part, Line designing

Method for straight lines

  1. Select your LINE-Spline
    "Create" -> "Geometry" -> "Compound Objects" lets you select "Loft".

    Taxilines gmax 06.jpg

  2. Click on "Get Shape".
  3. Open up the "Select by name" window.
  4. Now, choose your template and pick it. TWYLINE_TEMPLATE in my case (that's why it's good to use a strong name ). There it is, your twy-line. Just zoom in to have a look at it.

    Taxilines gmax 07.jpg

Note: Make certain you have the Top window rendering method reset set to Facets or higher in order to see your bitmap appear.

  1. Simply apply your twy material to the loft. No extra uvw mapping needed Play with the surface parameters: If you need a repetetive texture, use the length repeat option. Else, just leave it as is.
  2. Import settings are the "Skin Parameters". Shape Steps lets you choose the "resolution" of your polygon in the "width"-direction. We don't need more than 0 steps!!! Path Steps is for the "resolution" along the line. For straight lines, a value of 0 gives us the best option. (least amount of polys -> 2 faces for each straight line!)

    Taxilines gmax 08.jpg

Method for bends

  1. Select your ARC-spline
    "Create" -> "Geometry" -> "Compound Objects" lets you select "Loft". Repeat Steps 2 to 5 from the straight line section!
  2. The good thing about lofting is the control over your "smoothness" of your bends. In "Skin Parameters" again, Shape steps are set to 0. But now, Path steps will refine your arc At 0, we have a fairly "hard" bend. Now increase the number until you think it looks good. But don't go crazy, keep the amount of polys in mind A value of 4-6 is already good imho!

    Taxilines gmax 09.jpg

  3. For demonstration, I used 15 here, and we have a smooth arc. Also, a benefit of lofting, the texture follows perfectly your line!

    Taxilines gmax 10.jpg

There you have it. Another Gmax-trick unveiled. For different Line-widths use, just create another templates. If you get the hang out of it, it's a really efficient way to create Twy-Lines in gmax. And don't worry about the spline "guides", they won't be exported with MakeMdl