HowTo/Solve Blender Modelling Problems

Revision as of 15:30, 23 May 2016

Using Blender for Making Trainz Content

The Blender 3D modelling software is ideal for making content for Trainz and many 3rd party add-ons, tutorials, and documentation may be found online. Examples include the main Blender site, BlenderNation and Blender Artists. A search of the web will reveal many others.

Blender is a complex software suite with extensive functionality, some of which is not yet usable in Trainz. People planning to use Blendr to create content for Trainz would be well advised to start by spending time building a Blender skillset. Besides a variety of printed materials available commercially, there are two courses which can help a prospective content creator learn to use Blender for creating content. One of these is a course geared towards high school students, taught by James Chronister, and available through the auspices of the Central Dauphin High School in Harrisburg, Pennsylvania. The other course is offered under the auspices of Tufts University in the US, and is geared towards college students. This course is taught by Neil Hirsig. If in doubt, take both.

Help specifically for Trainz purposes is harder to find. There are the "How/Tos" on this site, some on WiKi Books, Ian Cayden's Blender Notes and Paul Hobbs' Tutorials . Paul Hobbs' site hosts tutorials for Blender using both pre 2.5 versions of Blender, and others converted to the current user interface (v. 2.50 and later).

Purpose

This page contains answers to frequently asked questions (FAQ) relating specifically to Trainz modelling and should be useful for both beginner and more experienced creators. The Trainz Blender community is encouraged to add their own submissions.

Asking for Assistance

When asking for help in the Trainz forums on issues related to using Blender for content creation, the following suggestions will help other members of the Trainz community assist you better.

1) Get an account with a hosting service such as dropbox, where you can upload files about which you have questions.

2) When seeking help with an issue related to Blender for content creation, upload a copy of your Blend file, and any other supporting files (textures, animations, screenshots, &c) to the dropbox file so that those who would wish to offer help can see the material with which you are working, and better understand the problems.

Exporting

Surfaceless Polygons

Symptom: The exporter log contains a message like this:

 15:33:10 WARNING: surfaceless Polygon(s) in Object "rdc12349end.001", Mesh "Cube.097" detected
 15:33:10 INFO:    Vertices of surfaceless Polygon(s) gathered in Vertex Group "ERROR_surfaceless_Polygons"

Comment: Surfaceless polygons (aka faceless faces) are polygons which cannot form a plane (face) between the polygons vertices. This problem often arises when an extrusion is initiated but not completed. In this case two or more vertices may occupy the same location. Here is another explanation by Torsten:

Let's call the corner points (vertices) of a triangle (the simplest possible face) A, B and C. As long as all three corners have different locations they define a plane, a two dimensional object. The part of the plane inside all three vertices is what we call surface or face. So far for the "good" case. Now the "bad" case. Imagine point B moves to the location of A: suddenly we can no longer tell if what we see is a triangle or a line. We can no longer define a plane because all three vertices now only form a line (of course a line with three points instead the necessary two points). As our triangle (aka polygon) now has no surface (we need a plane -> 2D and have a line -> 1D) we have created a "surfaceless polygon".

The exporter itself needs a plane because for every exported triangle Trainz want to know its normal (to calculate the color of that face for example), and a 3D normal needs a 2D plane. Try to calculate the normal for a surfaceless polygon will end in a division by zero.

Solution: This can be cured by selecting the mesh and using the "Remove doubles" command. You can identify the problem vertices by selecting the problem mesh and then going into the Properties Browser and the Object Data (the triangle) tab. There is a section called Vertex Groups and the newly created vertex group with the problem should be listed. There are options to highlight the vertices in the group.

Comment: Another cause of surfaceless polygons is when there are two edges that seem to join, but where the edge on one side does not have the same number of vertices as the edge on the other. As an example, if one starts with the default Blender cube, and extrudes the top face of the cube to create a first story. and extrudes the top face again to create a second story, the result is a stack of 3 "cubes". Now, if one decides to add a door, or a window, in one face of the center cube of the stack by deleting the center face one side, and extrudes both vertical edges towards the center, and then makes a face from the two resulting extruded edges, one has created two surfaceless polygons, one from the four vertices that lie in a line at the top of the door, and one from the four vertices which lie at the bottom.

Solution: A modificaton of the work flow. If one decides to add a opening, instead of deleting the face, and creating the opening by extruding edges or vertices, either make loop cuts around the object as needed, and delete the necessary face, or subdivide the face

See Also: This Trainz forum thread

Making updating updating from one version of Blender to the next easier

Blender updates every couple of months, on the average. One way to make the updating process easier is to store any Blender add-ons you use that are not included in the ordinary Blender distribution in a convenient place on your computer. Among the things to store in this folder are the latest version of the Trainz mesh exporter, and the Trainz mesh importer. This makes it easy to make the new version have all of the material of the old one, as it is simply necessary to copy the contents of the update folder into the appropriate locations of the Blender installation.

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