Doc_Halo1_ShaderExtension

Shader Extension

Object Shader Extensions

Specular Map

The specular map allows you to change the colour of the models specular reflection at the pixel level.

Field	Type	Usage
specular color map	tag reference	The specular colour map.
specular color coefficient	real	The specular map colour is multiplied by this value. 0 defaults to 1.
specular color exponent	real	The specular map colour is raise to this power. 0 defaults to 1.
flags	word flags	Sets whether to use the alpha channel as an exponent mask.

Normal Maps

Normal maps allow you to add per pixel details to a model. They are typically created by baking the surface normals of a high resolution model into a bitmap using the texture coordinates of a low poly model. Normal maps must be in tangent space.

Detail normal maps can be used to add further close up details. The alpha channel of the base normal map controls how the detail normal maps are blended.

Alpha range	Usage
0/0.000 ===> 85/0.333	No detail normals to detail normal 1.
85/ 0.333 ===> 170/0.666	Detail normal 1 to detail normal 2.
255/1.000 ===> 255/1.000	Detail normal 2 to no detail normals.

Field	Type	Usage
base normal map	tag reference	The base normal map.
base normal coefficient	real	The strength of the base normal map.
detail normal 1 map	tag reference	The first detail normal map.
detail normal 1 coefficient	real	The strength of the normal map. 0 defaults to 1.
detail normal 1 scale	real	The texture coordinate scaling of the normal map. 0 defaults to 1.
detail normal 1 v-scale	real	The additional V-texture coordinate scaling of the normal map. 0 defaults to 1.
detail normal 2 map	tag reference	The second detail normal map.
detail normal 2 coefficient	real	The strength of the normal map. 0 defaults to 1.
detail normal 2 scale	real	The texture coordinate scaling of the normal map. 0 defaults to 1.
detail normal 2 v-scale	real	The additional V-texture coordinate scaling of the normal map. 0 defaults to 1.

Specular Tint Override

The specular tint override replaces the matching values in the base tag, since you may want different values to compliment the specular colour map.

Field	Type	Usage
perpendicular brightness	real fraction	The brightness of the perpendicular specular reflection.
perpendicular tint color	real argb colour	The tint colour of the perpendicular specular reflection.
parallel brightness	real fraction	The brightness of the parallel specular reflection.
parallel tint color	real argb colour	The tint colour of the parallel specular reflection.

Diffuse Lighting

This section only applies when using the shader on BSP.

Field	Type	Usage
flags	word flags	Controls whether directional lightmaps should be used with this shader.

Specular Lighting

The OS shader model shaders allow you to have specular reflections on your models.

Field	Type	Usage
specular lighting exponent	real	The specular reflection is raise to this power, which controls the size of the highlight.
specular lighting coefficient	real	The specular reflection is multiplied by this coefficient, which controls the brightness of the highlight.

Environment Shader Extensions

Directional Lightmaps

OpenSauce adds directional lightmaps to the engine (As used in Valve's source engine) which allows you to have normal mapped static lighting on BSP. The shader uses the shader environments normal map.

Directional lightmaps are created in 3DS Max using the provided lightmap rendering script, or in Maya using it's built in DLM renderer (used to be called Turtle). The rendered lightmaps are added to the scenario tag as part of the BSP modifier system.

Field	Type	Usage
flags	word flags	Controls whether directional lightmaps should be used with this shader.
bump amount	real	Controls the strength of the shader's normal map.

Specular Directional Lightmaps

With access to directional lightmap data it has been possible to add a type of static specular lightmapping to the engine. The shader uses a reflected eye vector to sample the diffuse lightmap to get the light accumulated from the specular direction. Specular DLM's are reliant on diffuse DLM's, so they will also be disabled if diffuse DLM's are disabled.

Specular DLM colour map

The specular map allows you to change the colour of the specular reflection at the pixel level.

Field	Type	Usage
specular color map	tag reference	The specular colour map.
specular color coefficient	real	The specular map colour is multiplied by this value. 0 defaults to 1.
specular color exponent	real	The specular map colour is raise to this power. 0 defaults to 1.
flags	word flags	Sets whether to use the alpha channel as an exponent mask.

Specular DLM tint and brightness

The specular tint and brightness values control the colour of the specular reflection at direct and glancing angles.

Field	Type	Usage
perpendicular brightness	real fraction	The brightness of the perpendicular specular reflection.
perpendicular tint color	real argb colour	The tint colour of the perpendicular specular reflection.
parallel brightness	real fraction	The brightness of the parallel specular reflection.
parallel tint color	real argb colour	The tint colour of the parallel specular reflection.

Specular DLM intensity

These values are not the same as those in the shader model tag. Lightmaps are pre-calculated colours values baked into a bitmap, and as such the data required to calculate the specular attenuation correctly is not available. So to get the specular attenuation, the shader uses the luminosity of the diffuse lightmap to which the following values are then applied. You will need to try it out and choose values that are best for you. This isn't a realistic lighting algorithm by any means but it can produces reasonable results.

Field	Type	Usage
specular lighting exponent	real	The specular reflection is raise to this power, which controls the size of the highlight.
specular lighting coefficient	real	The specular reflection is multiplied by this coefficient, which controls the brightness of the highlight.

Effect Shader Extensions

The effect shader is a transparent shader used in particle systems. As such, you will find extension values available in the contrail, particle, particle_system and weather_particle_system tags.

Depth Fade

Effect depth fading allows you to soften the edges of your effects when close to opaque meshes, and when close to the camera. Depth fading relies upon the depth buffer in the GBuffer. If the GBuffer is disabled or unavailable, depth fading will not be used.

Field	Type	Usage
depth fade distance	real	The fade out start distance when close to an opaque surface.
camera fade distance	real	The fade out start distance when close to the camera.

In-game, off-on comparison: From: http://forum.halomaps.org/index.cfm?page=topic&topicID=47823&start=387 ImageBackup WebpageBackup