3. Simple Construction - A Diesel Loco - Part One


Version 1.0 - 1. July 2002

Our Goal

This shall be our first loco:
Rangierlok

We have to construct these parts:

  • Chassis
  • 3 Wheelsets
  • Frame - Main
  • Front Bonnet
  • Back Bonnet
  • Cabin
  • Roof
  • 2 Bumper Supports
  • 4 Bumpers
  • 4 Lights
  • 2 Coupling Rods

For texturing (painting) we need:

The genuine images in windows .bmp- and in CorelDraw! 8.0 format can be downloaded here for further manipulation.

Let's Start

We construct the chassis out of a simple box. A box in Gmax belongs to the so called Standard Primitives which are among others:

  • Box
  • Sphere
  • Cylinder
  • Torus
  • Plane
  • Cone
  • Geo-Sphere
  • Tube

In the toolbox (shown above) we choose the left tab (Create). In the drop down list, we choose Standard Primitives and the object type Box


The create box options appears:

The parameter values:
  • Length Segs
  • Width Segs
  • Height Segs

should all read 1.

The checkbox Generate Mapping Coordinates has to be checked.

Caution!

Everytime a new box is created, this checkbox has to be checked again.


The mouse pointer changed its shape into a double cross. Now we pull a square in the top viewport. To do this, we place the cursor into the upper left region of the viewport, press and hold the left mouse button, draw the mouse to the lower right section of the viewport and release the mouse button. The result should look like this:

The German text reads: Pull from here - to there


Now, we watch the front viewport, while we carefully push the mouse away. The box is getting its third dimension. When the box seems high enough, we click again and our first Object has been created. The colors of the objects are randomly chosen by Gmax, therefore they may vary.

The German text reads: Push from here - to there and In perspective viewport, the result looks like this:


In the Top, Front and Left viewport we see a wireframe model of the box, and in the perspective viewport we see a solid model. We now want to switch the Top, Front and Left viewport to solid mode. To do so, we rightclick onto the Text Front in the Front viewport. Now this menu should show up:


For the viewports Top, Front and Left we choose Smooth and Highlight and Edged Faces.
We leave the perspective viewport setting at Smooth and Highlight

The box will become the chassis of our loco. To edit its geometry, we first have to convert it into an Editable Mesh. The object to be converted must be selected first. A selected object is shown with different coloured edges, provided, edged Faces is chosen in the viewport. In the field Name and Color the name of the object is displayed.

If the box is not selected, we click onto the select arrow in the main toolbar and click on the box to select it. Once selected, we rightclick on the box. The so called Quad menu appears:

If the quad menu looks like this...

we have to change the font with the Customize - Customize User Interface - Quads - Advanced Options - Fonts and Title Fonts option.

In the quad menu, we choose Convert to - Editable Mesh, which we will do in the future with every object we wish to manipulate or edit.

The toolbox on the right shows the mesh edit options.


Excursion

Our box, a rectangle, consists of six planes, called Polygones (from greek poly = many, much and gon = corner). Each of the polygones consists of two triangles, called Faces. A face is a plane in a virtual world with the special property to be seen only from one direction, which is called the Normal.

Given, our point of view would be the inside of the box, the faces of it would be invisible to us because the normals point to the outer direction.

A face is described by three locations (points) in space which are on the corners of the face (which is has a triangle shape). The reason to take just three points to describe a face, is the fact, that only a construction with three points results in a flat surface, wherever the points may be, provided, the points do not share the same place.

This points are called Vertices (singular Vertex). The location of a vertex in space is given by three coordinates, X (left-right), Y (front-back) and Z (height). If a plane has more than three vertices, it is called polygon rather than face.

All 3D-construction programs work with faces, some, including Gmax, work with polygones too. That makes it much easier to create complex objects. Internally, all programs are working with faces.

In Edit Mesh mode, we can edit, create, delete, move, rotate, scale or otherwise manipulate objects.

The just created box is an object to Gmax. In addition to the faces, an object has other properties, such as material, which determines the color and look of the object. An object can be linked to another object, the parent object. A linked object is dependant to its parent. This would be the case for a coupling rod, which is dependant to the wheelset.

The MSTS needs to know how to move or rotate an animated part of a wagon or loco. Vehicles in MSTS are always considered animated. That does not include automobiles. To show MSTS how to rotate an object, it has a so called Pivot Point.

Caution!

While working with Gmax, it is essential to know, that while in edit mesh mode, the pivot point is not affected at all. While in Object mode, the pivot point is moved with the object.

Caution!

Scaling, moving, rotating and other so called transformations (XForm) are only to be done in edit mesh mode! Otherwise, Gmax will crash while attempting to export the project or MSTS will crash while loading the loco.


Now, we have to position and resize our box. To do this, we change to Vertex Mode:

The vertices are shown in blue:

In the Left viewport, we select all eight vertices of the box by drawing a bounding box around the box and then release the mouse button. The chosen vertices change their color to red. We see also three arrows, which shows the direction of the object inside the virtual world. The direction of these arrows do not match our virtual world direction. This does not matter at this moment. We're going to fix it later.


Next, we click the icon Select and Move, and in the center of the selected vertices three arrows and one corner-symbol appear:

In perspective viewport, three arrows, and in the other viewports, two arrows are visible. The cursor, once moved onto an arrow inside an active viewport (which is the viewport with the white frame) changes to a cross-arrow shape. Now we can move the vertices, and with them, the faces the direction the arrow indicates.

The small yellow corner allows the selection to be moved in both directions at the same time.

Caution!

Clicking into another viewport or a space where no cross-arrow shape appears will deselect the vertices.

Now we try to drag the box onto the middle of the viewport. The black lines give us orientation aid, as they indicate the virtual world's center. The result should look like this:


Before giving the vertices their exact position values, we have to make sure, that Gmax should use meters rather than inches or feet. To do so, we open the menu customize-preferences

We make sure, that System Unit Scale shows 1 Unit equals 1 Meter. If not, we change the setting. This is necessary to give our objects the right size in the MSTS world.

Concerning the views:

While constructing a loco or wagon for MSTS, the Left viewport shows the loco directing to the left as expected. The Top viewport shows the loco directing to the top of the screen. The Front viewport actually shows the Backside (!) of the loco.

The chassis, to which we will convert our box to, has a length (Y-direction) of 9 meters, a width (X-direction) of 1.3 Meters and a height (Z-direction) of 1 meter. The chassis is centered in the virtual world system and hovers in a height of 0.5 meter above zero, which means above the rail in MSTS.

In the Left viewport, we select the upper vertices.

In the Top and the Perspective viewport we see, that the backside vertices are selected as well. To give the vertices thier correct values, we have to open the Transform-Type-In dialogbox by rightclicking onto the Move symbol (Cross-Arrow).


The upper vertices are selected. In the dialog box Absolute World Z we type in the value 1.5 and press enter. The upper side of the box is moving to 1.5 meter above zero.

Caution!

To type in decimal values with a point as a decimal separator or a comma, as we do in Germany, might depend on the language setting of your computer.

we select vercices and type in the values as follows:

  • The lower vertices to Z 0.5 meter
  • The front vertices toY 4.5 meter (to be selected in the Top viewport)
  • the rear vertices to Y -4.5 meter (to be selected in the Top viewport)
  • The right vertices to X 0.65 meter (to be selected in the Front viewport)
  • The left vertices to X -0.65 meter (to be selected in the Front viewport)

The box may appear very small now. Therefore we have to zoom in with the view control:


With the upper right symbol all objects are zoomed in to their extends. (Clicking two or three times may be necessary). The symbol below, the one showing two rectangles and an arrow, switches the active viewport to fullscreen mode and vice versa. This can also be achieved with the W-key.

The next step is to bevel the front and rear sides of the chassis. We select the lower left vertices in the Left viewport an in the Transform-Type-In dialog, we type in a Y-value of 3.75. We do the same with the lower right vertices but type in -3.75 rather than 3.75. The result should look like this:

In the toolbox, we type in the new name "chassis" and deactivate the vertex-mode.

Caution!

The images in this tutorial are taken from the german version of this tutorial. I gave the loco parts a name in german language. Thus, the pichtures read "Fahrgestell" which means chassis in english


In order to place the chassis in the correct place within MSTS, we have to set its pivot point zo zero. To do so, we select the chassis and open the Hierarchy tool:
Here, we click the Pivot, then the Affect Pivot only button...
...then the Center to Object and Align to World button.

Having a closer look, we would notice that the pivot point is placed in our objects center, but not in the center of MSTS' virtual world. Once exported into MSTS, the chassis would sink halfway into the ground because the chassis' pivot pount ought to be placed onto the top of the rail.

Caution!

This is the case for all objects except the wheels (wheelsets).

To give the pivot point its proper height, we open the Transform-Type-In dialog. (Remember? rightclick onto the move symbol). The height value (Z) might still read 1 meter:


AllAbsolute World X-, Y- and Z- values are due to be set to zero, which should already be the case for the X and Y value. The pivot point now looks like this:


Now we deselect Affect Pivot only. The chassis is done for now, it will be textured later.

In our Trainsimulator Trainset folder, we create a new folder and name it gtd1 (which means Gmax Tutorial Diesel loco no. 1). Into this folder, we save the file with the name gtd1_01.gmax.


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to construction part 2