Dream Shader Decompile

dream-shader-decompile <asset>

Read an existing asset's node graph and write the DreamShaderLang source that builds it. Since 2.0 the default output is 2.0 text — a .dss, a .dsi for a material instance, or (since 2.1.0) a .dsp for a Custom Pass pipeline — written by the compiler run backwards (graph → IR → AST → printer; a pipeline has no graph, so its fields are read back into the payload a .dsp binds to). The 1.x exporter that writes .dsm / .dsf is still there behind -Format Legacy.

This is the front half of a migration; the back half is dream-shader-optimize.

Paths below are relative to the plugin root, Plugins/DreamShader/.

Run it

pwsh -File Plugins/DreamShader/.skill/dsc.ps1 decompile /Game/Materials/M_Steel

pwsh -File Plugins/DreamShader/.skill/dsc.ps1 decompile /Game/Materials/MI_Steel_Worn

pwsh -File Plugins/DreamShader/.skill/dsc.ps1 decompile /MyPlugin/Materials/M_RectBlock -Out D:/Work/M_RectBlock.dss -KeepAssetPath

Exit 0 writes the file and logs where, and in which format:

LogDreamShader: Display: DreamShader decompiled '/Game/Materials/M_Steel.M_Steel' to '…/M_Steel.dss' (dss).
dsc: OK (exit 0)

Without -Out the destination is computed from the asset's package path:

So /Game/Materials/Metal/M_Steel → DShader/Decompiled/Materials/Game/Materials/Metal/M_Steel.dss. With -Format Legacy the same places get .dsm / .dsf, and an instance or a pipeline is refused.

What comes out

// Decompiled by DreamShader from /Game/Materials/M_Steel.M_Steel
uniform float A = 1.0;
uniform float B = 2.0;

export void M_Steel(inout material m)
{
    float Sum = A + B;
    float Twice = Sum * Sum;

    m.Opacity = saturate(Twice - Sum);
    m.Roughness = A * 0.5;
}

• Uniforms come out in the material's display order; /// @sort is written only where a priority is not the uniform's place in that order.
• A value gets a local when it is read twice, or when the statement that made it named it; the rest is written inline.
• A Custom node comes back as a /// @custom function with its helpers; a function asset the graph calls becomes an extern prototype with /// @asset.
• Comment boxes are #pragma regions, node positions are #pragma layout hints.
• A material instance comes out as a .dsi: its parent, the #pragma instance keys it overrides, and only the parameters that differ from the parent.
• A DreamShader thin-custom pair (hidden MB_DreamThinBase_* base + instance) is decompiled as the one material it is — pass the instance. Backend = ThinCustom is written only where it is not the project default anyway, or with -SourceFile / -KeepAssetPath.
• A Custom Pass pipeline comes out as a .dsp: #pragma pipeline, the uniforms, the buffers and the passes in the asset's order, every key that would read back as its default left out. What the text cannot say the way the asset has it is DSH9211–DSH9220; the text is then parsed and bound again and compared with the asset (DSH9221–DSH9223, warnings — the file is written either way). Docs/tools/decompiler.md has the details.

After the export — do this, in order

1. Read the // Warning: DSHnnnn: … lines under the // Decompiled by DreamShader from … header. Each names something the text cannot state the way the asset has it (warnings of DSH9060–DSH9084; for a pipeline DSH9211–DSH9220) — the notes of those ranges stay in the log. They are the migration work list; Docs/diagnostics/DSH9xxx.md says what each one means and what to do about it.
2. Compile it as-is, to establish that the export is at least buildable:

   pwsh -File Plugins/DreamShader/.skill/dsc.ps1 compile DShader/Decompiled/Materials/…/M_Steel.dss -Force -CleanNew

   Without -KeepAssetPath this is safe by construction: a .dss builds its asset where the file is, so a file under Decompiled/… builds a new asset (/Game/Decompiled/Materials/…) and leaves the original alone.
3. Clean it up — dream-shader-optimize.
4. Only then let it take over the original: move the file to the place that names the original asset, or add /// @name /Game/Materials/Metal/M_Steel to the export (what -KeepAssetPath would have written), and delete nothing until the rebuilt asset has been looked at.