Texture Modding

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Revision as of 17:06, 5 January 2014 by Scrawl (talk | contribs) (Added material overrides system)
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NOTE: This page describes features that are implemented in GIT, but haven't been released yet.

Objects

NIFs

NIFs are unfortunately a bit limited in that they don't allow specifying material properties (such as a bump map) externally, meaning that after creating a bump map for a color texture you'd usually have to edit all meshes that use this texture and distribute the meshes with your mod.

With OpenMW, as of GIT@83a46b79f2319ff, there is an alternate way:

Material overrides

Create a file called texture-overrides.cfg and place it in one of the following locations:

- Windows: <OpenMW installation root>
- Linux: /etc/openmw or build folder for a local build
- Mac: ?

The file must be a simple INI file. For each base texture, a list of overrides can be specified.

[textures\tx_hlaalu_wall2_01.dds]
normalMap = textures\tx_hlaalu_normal.dds
specular = 1 1 1 64

The full list of override keys can be found in the objects.mat file.

Normal mapping

If using material overrides, use a 'normalMap = <Path to normal map>' line. You can also edit meshes and assign the normal map to the BumpTexture slot of the NiTexturingProperty.

Parallax

Parallax mapping is similar to normal mapping, except that the alpha channel contains height information. To tell OpenMW that height information is available, make sure your normal map filename contains "_nh." (stands for normalHeight). Example: Tx_BM_snow_01_nh.dds

Please note that the strength of the parallax effect is not adjustable at the moment. However, to reduce the effect you can simply scale the heights. Height 0.5 is the base level where no view dependent offset is performed.

Specular

First, make sure that specular is enabled in general.

If using material overrides, add this line:

specular = <R> <G> <B> <S>

RGB is the specular color and S is the shininess.

Example:

specular = 1 1 1 64

If editing the mesh:

  • Add a NiSpecularProperty and make sure the 'flags' field is set to '1'.
  • In the NiMaterialProperty, make sure the specular color is set properly and glossiness is valid.

Shininess/glossiness

Valid shininess values are from 1-128. Values higher than 128 may work, but are not supported on all graphics cards. The higher the shininess, the 'sharper' the specular effects will look.

Specular mapping

Shiny and non-shiny parts along the texture can be defined by storing a specular mask in the alpha channel of the color texture. alpha 1 = shiniest, alpha 0 = no specular.

Obviously, for alpha-blended (or alpha-tested) materials, the alpha channel is already used for transparency, so specular mapping those is not possible yet.

Native format

We plan to have native mesh/material formats in the future, but this is still in the planning stages.

Terrain

Specular mapping

The specular mask is stored in the alpha channel of the color texture.

Note that contrary to what you'd expect, alpha=1 means no specular and alpha=0 means full specular. This is because Vanilla's default textures aren't supposed to have specular.

Normal mapping

Normal maps need to be named with an _n postfix. For example, for a color texture Tx_BM_snow_01.dds, OpenMW will look for a normal map called Tx_BM_snow_01_n.dds.

Parallax mapping

Parallax mapping is similar to normal mapping, except that the alpha channel contains height information. alpha = 1 -> highest, alpha = 0 -> lowest. Also, the filename postfix you need to use becomes _nh (e.g. Tx_BM_snow_01_nh.dds) so that OpenMW knows that height information is available.