Shader Builders (.shader_builder)

Many shaders in Spore are not coded in a single .hlsl file directly. Instead, they are generated by combining different pieces of code, known as Shader Fragments. These fragments are then combined under certain conditions in the Shader Builder files.

A shader builder contains two lists of references to fragments, with certain conditions that the game must meet for that fragment to be selected. When the game needs a shader, all these conditions are checked, the correct fragments are selected and merged, and a shader is generated.

There are two types of list, both must be included in the same file:

• vertexShader: Can only use those fragments that end with the .vertex_fragment extension.
• pixelShader: Can only use those fragments that end with the .pixel_fragment extension.

For example, a builder list for a vertex shader might look something like this:

vertexShader
    add copyVertexColor -elements color
    add getAngle
    add toClipSpace
end

In this example, there are fragments that are always selected (getAngle and toClipSpace) and other that depend, in this case, on whether the model has vertex colors.

Select groups

Apart from using add to add fragments, it's also possible to choose one from a group of possible selections. For example:

group 0x1
	select applyShadowMapTerrainNest -compareData shadowMapInfo 3
	select applyShadowMapTerrain -compareData shadowMapInfo 2
	select applyShadowMapNull
end

This will select, at most, only one of those fragments; if applyShadowMapTerrainNest cannot be used, it will try with applyShadowMapTerrain, and so on. It is possible that no fragment in the group is selected at all. Notice that inside a group, you use select instead of add.

When defining a group you must also give it a name.

Attributes

Both add and select have the same attributes and options:

add fragmentName

select fragmentName

fragmentName is the name of the fragment to be used; if this is inside a vertex shader only vertex fragments can be used, and the same goes for pixel shaders.

Conditions

Add and select instructions can have certain conditions that define when these will be used. If no conditions are specified, then the fragments are always used.

These conditions are mutually exclusive, meaning that only one of them can be used:

• hasData dataNames...

Uses the fragment if the game has defined data for the specified Shader Data names; you can use from 1 to 3 names. For example, add myFragment -hasData skinWeights cellStage

• compareData dataName value

Uses the fragment if the game has defined data for the specified Shader Data, and that has the same value as specified. For example, select myFragment -compareData shadowMapInfo 2