Shaders

Shaders are SHD files loaded by the NWN:EE engine to perform graphical changes to textures. There are vertex (per-vertex) and fragment (per-pixel) shaders that are run by the game.

Using shaders you can alter the graphical presentation of textures and models.

Basic Shader Overview

Shaders are text files loaded by the engine and compiled onto the GPU for changing how textures and models look at run time.

There's really just a few real separate shaders. The vs and fs prefixed files just have key flags that get turned on and off to make the shaders do different things, like yes or no use normal, spec, roughness, etc. In general the VS ones get your vertex properties all set up. The FS ones basically paint your screen pixels using the information gleaned from the nearest verts. And then there's a post-processing layer that does your stuff like sharpen and screen depth type stuff. And finally there's your shadow and beaming projectors. 

For the most part the base game doesn't offer a set of special shaders to change too much at all except the water shader.

If you want to add something like an alpha override instead of just putting the alpha in the diffuse alpha layer like you should, then you can pick a texture # between 6 and 10 and add that texture in there. Then write a super simple shader mod to just get your alpha from that B&W map instead of the diffuse.

How Does NWN Load a Shader

There are several entry points for shaders:

• To load a custom shader for custom content you need to add a customshaderVS and customshaderFS line in the MTR file for that specific texture. There used to be an old way to do this in TXI files as well (but don't use TXI files any more!)
• To use some shader things like Standard material inputs then only specifying a renderhint is required
• The game has several default ones loaded - some are only loaded when certain Game Options are selected such as "Depth of Field" or "Sharpen". Others are loaded as general stock ones for different models.

See below for what stock shader files there are and where they are used.

Generally you don't want to override the games default shaders; need to edit in here when tested since it might only be possible to do at game launch.

Stock Shader Files

Shader files are generally in the base_shaders.bif file - extract this most easily with NWN Explorer. Up until relatively recently the shader files may have undergone significant changes and were included in the /ovr folder in the game installation directory. These were folded back into the bifs later.

From looking at them there are not many comments and no easy to follow examples for new modders. You probably want to learn about shaders - an old tutorial where some of this is from is here and hopefully a few tutorials will be added to this wiki in time.

The game ships with a set of stock shaders. Many of these emulate behaviour of the old 1.69 NWN engine. First step in modifying one of the stock shaders is figuring out which one is used for the model in question. The shaders mostly follow a naming scheme based on what they take as input:

• lit means the shader uses dynamic lighting
• _sm means the object is sphere-mapped,
• _cm means the object is cube-mapped
• t means the shader has texture coordinates
• c means the shader is given a specific color by the engine
• v means the (vertex) shader gets the vertex coordinates
• _ls means the shader is using long-distance fog
• _sk means the shader is using the m_bones skeleton
• fb tends to be post-processing game options

A list of standard shaders included in the game files and what they're used on - when someone gets around to fully testing.

If you're not sure which stock shader is used for a given model, you can:

a) Load a GL debugger/tracer and check glUseProgram() calls

b) Modify each FS to show a different solid color, then check the color of the model, eg:

void main() 
{
	gl_FragColor = vec4(1.0, 0.0, 1.0, 1.0);
}

SHD Format

Shaders are relatively standard text files, written in c-like code.

Generally each shader you'll want to use for model texture changes will include "inc_standard". They also will use #define to setup what the shader file will do. For instance fslit_nm has the normal, specular, roughness height and self-illumination maps set (the "nm" means "normal maps"):

//=============================================================================
//
// fslit_nm.shd
//
//=============================================================================

#define SHADER_TYPE 2

#define FOG 1
#define KEYHOLING 1
#define LIGHTING 1

#define NORMAL_MAP 1
#define SPECULAR_MAP 1
#define ROUGHNESS_MAP 1
#define HEIGHT_MAP 1
#define SELF_ILLUMINATION_MAP 1
#define ENVIRONMENT_MAP 0

#include "inc_standard"

void main ()
{
    FragmentColor = vec4(1.0);
 	SetupStandardShaderInputs();
    ApplyStandardShader();
    gl_FragColor = FragmentColor;
}

Editing Parameters Dynamically via. nwscript

There is actually a way to edit some shaders - when applied to a specific texture on a specific object - via. nwscript. The object in question must be able to be referenced by, say, tag, or OBJECT_SELF - you can't apply this to specific tiles in a area's tileset for instance, or to set a general change on every general shader.

This can be used to quickly test some parameters though. For example this could be your MTR file, in this case called c_ettercap.mtr - overriding the c_ettercap.mdl main texture file.

customshadervs vslit_nm
customshaderfs fslit_nm
renderhint NormalTangents
// Textures
texture0 c_ettercap_d
texture1 c_ettercap_n
parameter float Specularity 0.02
parameter float Roughness 0.1

In this case we specify the diffuse, normal maps and force on the specular and roughness as uniform values - we don't need to supply a texture file.

This is limited of course to applying the same value across the entire model but is great for testing. In game you can run this code in the debug window when selecting the Ettercap to run it on:

float fSpecularity = 0.02;
float fRoughness = 0.05;
SetMaterialShaderUniformVec4(OBJECT_SELF, "c_ettercap", "Specularity", fSpecularity);
SetMaterialShaderUniformVec4(OBJECT_SELF, "c_ettercap", "Roughness", fRoughness);

You can also do this for the "metallicness" value but this tends to be auto-generated. This provides some instant results, eg:

Some examples: