Wavefront OBJ Import

Terragen can import a limited form of Wavefront OBJ files (.obj extension). It can import geometry and material information.

Geometry

TG only imports three and four sided polygons. Polygons with 5 or more vertices/sides are not supported. It also doesn't support freeform/spline curves or surfaces like NURBS.

TG can load normals and texture coordinates.

TG loads groups and objects and any materal assignments for them. See below for more information on materials.

Materials

TG can read material data from an MTL (.mtl extension) file referenced by the OBJ file.

TG reads diffuse and specular values from the MTL file. It can also load a diffuse texture file in any of the image formats TG supports.

Nodes Created

OBJ files are loaded by an Obj reader node. Materials are added to an object using a Parts shader node which is created in the internal network of the Obj Reader node. Each group of the object with a material assigned also has two further nodes created for it in the internal network on the Parts shader. For each group an Object part node is created. This node has a Default shader assigned to it which holds the actual material settings loaded from the MTL file. If you want to change the material settings then you need to go down through these internal networks and change the Default shader for that particular part of the object.

A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.

A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.