rtx: Add MaterialX (.mtlx) material support#348
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Registers the materialx subtype and the VISRTX_MATERIAL_MATERIALX extension. The MaterialX MDL support modules ride the MDL search path — resolved from the FetchContent source tree for in-tree builds, the installed libraries/mdl layout otherwise. Commit transcodes the document to MDL behind a change guard and exposes a materialNames property. TestMaterialXMaterial compiles with USE_MATERIALX so the advertised extension flag matches the device build.
…rface builtin Transcoder emits a clean-name -> generated-MDL-arg map so ANARI parameters keep their MaterialX names. Bundles standard_surface.mtlx and resolves the visrtx::standard_surface builtin against it.
materialx material token with a bare-constructor branch, a StandardSurface preset helper, and MaterialX/StandardSurface entries in the material menu.
The transcoder splices an <image> node in front of each texture-bindable constant input and pairs it in the paramMap (carrying origin path and type); ANARI samplers then route through the spliced nodes by pure arg binding, and a re-commit no longer reverts textured inputs. Only 2D image samplers (image2D / compressedImage2D) bind — a spliced MaterialX image lowers to an MDL texture_2d — checked locally at the bind site rather than on the Sampler base. Also fixes MDL search-path init: the search paths are now applied from initMDL (via syncMdlSearchPaths), not only from deviceCommitParameters. On the lazy-init path (app never commits the device) the bundled MaterialX support-module path was left unset, so the generated MDL failed to compile.
…a render gate When a document has no renderable element, instantiate its file-local surfaceshader nodedef. The file is read before stdlib import so auto-instantiation sees file-local nodedefs.
Transcoder takes a DocumentSource (file or inline) with snapshot provenance; the documentInline scheme survives when only source is re-set.
The implicit-input materialization (for inputs absent on the node instance, e.g. the bundled/auto-instantiated standard_surface) looked the input up with NodeDef::getInput, which only sees DIRECTLY declared inputs. standard_surface's default nodedef declares just base/base_color directly and inherits the other ~40 (emission_color, metalness, ...) from ND_standard_surface_surfaceshader_100, so getInput returned null for them, the splice was skipped, and binding a sampler to such an input failed with 'sampler not bound (image2D textured input required)'. base_color only worked by being one of the two direct inputs. Use getActiveInput, which resolves inputs through nodedef inheritance. Adds a transcoder test binding emission_color (verified to fail before the fix).
Classifies wired filename ports as texture-bindable rows, exempts them from retranscode topology, and exposes a textureInputs discovery property. Device-side sampler binding is not implemented yet.
A MaterialX standard_surface transcodes its emission to a coat-over-base EDF — df::unbounded_mix([edf_component(saturate(coat), directional_factor(diffuse)), edf_component(1-saturate(coat), diffuse)]) — so the ADR-0007 classifier rejected it (Directional kind + unknown intensity sign) and synthesized NO Geometry Light. The emitter then lit receivers only via the forward path, so its NEE pool was fainter/noisier than the equivalent physicallyBased or raw-MDL emitter. Four folds let the classifier see through the coat wrapper when coat is 0: - model math::saturate (nonnegative, in [0,1], zero iff the argument is zero); - prune a provably-zero-weight df::edf_component from a mix's kind union, so the view-dependent coat branch drops at coat=0 and only the diffuse base remains; - stop descending into a modeled EDF leaf's operands in the mix deep-scan — the diffuse_edf handle string is an Opaque node that otherwise poisoned the mix to Unknown (now matches the evalEdf leaf path); - fold a - 0 = a in combineSub, so the 1 - saturate(coat) layer weight resolves to the constant 1 and the intensity sign is ProvablyNonnegative. Pruning keys on the arg-block value, so a genuinely coated emitter (coat>0) keeps the view-dependent branch and stays unregistered (unfaithful), per the miss=variance / over-register=bias policy. Also classify the textured emitter: MaterialX's <image> node lowers to a materialx::stdlib_*::mx_image_* wrapper (a tex::lookup with an invalid-texture default fallback), NOT a bare tex::lookup intrinsic — so it carries no DS_INTRINSIC_TEX_LOOKUP semantic and the emission IR saw it as an opaque call. Recognize the mx_image_* family by name and treat it as a texture lookup whose texture is the mxp_file argument. The DB-name match is sound here (unlike EDF-leaf recognition, which stays semantics-only): a texture lookup only supplies a Pick-Power mean, so a misrecognized or unbound lookup folds to zero — variance, never bias.
Replace the compile-baked MaterialX paths with a runtime search chain: materialxSearchPaths device param -> MATERIALX_SEARCH_PATH -> mx::getDefaultDataSearchPath() -> compile-time last resort. The MDL implementation modules dir derives from the winning root. Delete the visrtx::standard_surface builtin alias and the shipped standard_surface.mtlx: applications author the instantiation inline (TSD preset does), the nodedef comes from the distribution.
jeffamstutz
approved these changes
Jul 18, 2026
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Adds a
materialxANARI material subtype to the VisRTX RTX device(
VISRTX_MATERIAL_MATERIALXextension). A.mtlxdocument — supplied as afile path or inline XML — is transcoded to MDL at commit time and rendered
through the existing MDL material path, so MaterialX materials get the full
MDL shading/emission pipeline with no new runtime backend.
The MaterialX standard library is resolved from a system-installed distribution at runtime,
not embedded or shipped (ADR 0008).
TSD gains a thin authoring layer (material token, a StandardSurface preset, a menu entry).
Requires
VISRTX_ENABLE_MDL_SUPPORT(MaterialX transcodes to MDL) and gated byVISRTX_ENABLE_MATERIALX_SUPPORT.