/usr/share/libwildmagic/Data/CgShaders/LightAmbient.fx is in libwildmagic-common 5.13-1ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28  | void v_LightAmbient
(
    in float3 modelPosition : POSITION,
    out float4 clipPosition : POSITION,
    out float4 vertexColor : COLOR,
    uniform float4x4 PVWMatrix,
    uniform float3 MaterialEmissive,
    uniform float3 MaterialAmbient,
    uniform float3 LightAmbient,
    uniform float4 LightAttenuation
)
{
    // Transform the position from model space to clip space.
    clipPosition = mul(PVWMatrix, float4(modelPosition,1.0f));
    float3 ambient = LightAttenuation.w*LightAmbient;
    vertexColor.rgb = MaterialEmissive + MaterialAmbient*ambient;
    vertexColor.a = 1.0f;
}
void p_LightAmbient
(
    in float4 vertexColor : COLOR,
    out float4 pixelColor : COLOR
)
{
    pixelColor = vertexColor;
}
 |