Fallout custom env map shader

//
// Generated by Microsoft (R) HLSL Shader Compiler 9.23.949.2378
//
// Parameters:
//
//   float4 AmbientColor;
//   sampler2D CustomEnvMask;
//   float4 EnvToggles;
//   samplerCUBE EnvironmentCubeMap;
//   sampler2D NormalMap;
//
//
// Registers:
//
//   Name               Reg   Size
//   ------------------ ----- ----
//   AmbientColor       c1       1
//   EnvToggles         c27      1
//   NormalMap          s0       1
//   EnvironmentCubeMap s1       1
//   CustomEnvMask      s3       1
//

    ps_2_x
    def c0, -0.5, 1, 0, 0
    dcl_pp_centroid t1
    dcl_pp_centroid t2
    dcl_pp_centroid t3
    dcl_pp t0.xy
    dcl v0.xyz
    dcl t4.x
    dcl_2d s0
    dcl_cube s1
    dcl_2d s3
    texld_pp r0, t0, s0
    mov_pp r1.x, t1.w
    mov_pp r1.y, t2.w
    mov_pp r1.z, t3.w
    nrm_pp r2.xyz, r1
    add r0.xyz, r0, c0.x
    add_pp r0.xyz, r0, r0
    nrm_pp r1.xyz, r0
    dp3_pp r0.x, r1, t1
    dp3_pp r0.y, r1, t2
    dp3_pp r0.z, r1, t3

    add r1.xy, r1, -r0

    dp3 r1.w, r1, r2
    add r1.w, r1.w, r1.w
    dp3 r2.w, r1, r1
    mul r0.xyz, r2, r2.w
    mad r0.xyz, r1.w, r1, -r0
    texld_pp r1, r0, s1
    texld_pp r2, t0, s3
    lrp r1.w, c27.w, r2.x, r0.w
    mul_pp r1.w, r1.w, c27.z
    mul_pp r0.xyz, r1, r1.w
    mul_pp r0.xyz, r0, c1.w
    mul_pp r1.xyz, r0, v0
    cmp_pp r0.xyz, -c27.x, r0, r1
    mul_pp r0.xyz, r0, t4.x
    mov_pp r0.w, c0.y
    mov_pp oC0, r0

// approximately 34 instruction slots used (3 texture, 31 arithmetic)