Texture file

Texture files are ASCII text format files describing a single texture. Texture files have a ".texture.txt" name extension, however when a texture file is specified within a Config.txt file or similar, the ".txt" must be omitted, leaving the ".texture" extension.

TODO: Merge .texture.txt Files page into this page.

File format

The user-editable *.texture.txt files are ASCII text formatted key-value pairs with the following options. Please note that this format is not the same (despite some similarities) as other text-based formats used by Trainz. Please be aware of the filename character restrictions when naming texture and image files.

Primary=diffusemap.bmp

This tag specifies the filename of the image file representing the color (R, G, B) channels of the texture. Any alpha channel in the image file is ignored. The resultant texture will have a pure white (100%) alpha channel.

Primary=diffusemap.jpg
Alpha=diffusemap.bmp

This tag combination specifies the filenames of the image file representing the color (R, G, B) channels of the texture and the image file representing the alpha (A) channel of the texture. The alpha channel image should be grayscale. Neither file should contain an alpha channel.

Primary=diffusemap.tga
Alpha=diffusemap.tga

This tag combination specifies the filename of a single image file representing the color and alpha (R, G, B, A) channels of the texture. In this case both tags must reference the same filename. The image file must contain an alpha channel.

Compression=dxt1

This tag forces the usage of a particular texture compression scheme. If omitted, Trainz will choose an appropriate texture compression scheme based on the contents of the supplied image files. If you don't have a specific effect in mind, don't include this tag. Valid options are 'none', 'dxt1', 'dxt3', 'dxt5'.

NormalMapHint=normalmap

The 'NormalMapHint' tag allows the texture to be specified as a normal map. By default, Trainz will assume that your texture is a diffuse map and will apply some processing options which are not appropriate for normal maps. You must specify this option for normal maps. Valid options are 'none' and 'normalmap'.

ModifyMap=flipgreen

The 'ModifyMap' option allows a texture's green color channel to be flipped. Some programs such as 3ds Max create normal maps with the Y axis facing the opposite way to what is expected by the Trainz shaders. This option can be used to make the bump effect look correct in Trainz. The option is applied by the Content Manager upon Commit. Valid options are 'none' and 'flipgreen'.

AlphaHint=opaque

The 'AlphaHint' tag allows you to force a particular alpha mode on the texture. Valid options are 'opaque' (meaning that the alpha channel is unused and effectively pure white), 'semitransparent' (meaning that the alpha channel is a grayscale blend) and 'masked' (meaning that the alpha channel is a pure black&white bitmap.) If omitted, Trainz will supply an appropriate value for this tag based on the Alpha channel. Specifying this option prevents slight discoloration in a mask texture from triggering the blended alpha path.

MagFilter=linear

Controls the filtering style for texel magnification. This is used when a texel is displayed at larger than real size (eg. a single texel is represented with more than a single pixel.) Valid settings for the magnification filter are 'nearest', 'linear', and 'default'. Trainz currently defaults to linear interpolation. Selecting 'nearest' will use a nearest-neighbor filtering mode which results in a "pixelated" output.

MinFilter=linear

Controls the filtering style for texel minification. This is used when a texel is displayed at smaller than real size (eg. a single pixel is represented with more than a single texel.) Valid settings for the minification filter are 'nearest', 'linear', and 'default'. Trainz currently defaults to linear interpolation. Selecting 'nearest' will use a quantized filtering mode which results in a "noisy" output.

MipFilter=linear

Controls the filtering style for texture mipmap selection. Mipmaps are used during minification to help prevent the moire effect pattern. The cost of using mipmaps is that the resultant image will blur slightly. The benefits of using mipmaps are reduced quantization noise and reduced memory footprint (since the higher detail mip levels can be unloaded when not in use.) Valid settings for the mip filter are 'nearest', 'linear', 'default' and 'none'. Trainz currently defaults to trilinear interpolation. Selecting 'nearest' will cause the hardware to select a single mipmap for each pixel, which results in visible banding at mipmap boundaries. Selecting 'none' will disable mipmaps, resulting in lower performance, higher memory usage, and "noisy" output.

Tile=st

Tiling refers to the ability for texture coordinates outside the range of (0.0 .. 1.0) to be treated as valid coordinates on an infinitely tiled texture. With tiling active, coordinates which pass the right side of the texture effectively wrap back onto the left side, and so on. Valid options include 's', 't', 'st', and 'none'.

Image formats

The following image formats are acceptable as source data for the Texture file:

• Targa (.tga) files. Targa is a lossless image format with optional compression and optional alpha channel.
• JPEG (.jpg) files. JPEG is a lossy image compression format with no alpha channel support.
• Windows Bitmap (.bmp) files. BMP is a lossless image format with no compression and optional alpha channel.

Notes on Image Editors

• The Targa Exporter plugin shipped with some older versions of Adobe Photoshop is broken and silently corrupts or discards alpha channels; a free update is available which resolves this issue.
• Some image editors do not support alpha channels on BMP files.

.txt file extension

Texture files have a ".texture.txt" name extension, however when a texture file is specified within a Config.txt file or similar, the ".txt" must be omitted, leaving the ".texture" extension. For example, a texure file named grass.texture.txt is specified in a KIND Groundtexture config file using the syntax texture "grass.texture".

Use of image files in place of texture files

Trainz has historically supported using any supported image file in place of a Texture file. This technique has obvious limitations and is no longer recommended.