Announcement: MDL SDK 2024.1.0 released

[mkroll]

Get the update on GitHub - NVIDIA/MDL-SDK: NVIDIA Material Definition Language SDK.

MDL SDK 2024.1.0 (381500.2959): 14 Jan 2025

Added and Changed Features

• MDL 1.10 Language Specification

  • Updated version to 1.10.
  • Changed of diffuse_reflection_bsdf to improved Oren-Nayar model by Fujii
    and added parameter multiscatter_tint.
  • Corrected description of multiscatter_tint parameter in sheen_bsdf.
  • Added parameter f82_factor to standard distribution function modifiers
    directional_factor and color_custom_curve_layer.
  • Added standard distribution function modifier microflake_sheen_bsdf.
  • Added standard distribution function modifier coat_absorption_factor.
  • Extended rules for the distribution function normal form with new BSDFs.

• General

  • Added IBaker::get_type_name() to obtain the type name for constants to be used
    for a given baker instance. Improved the baker documentation w.r.t. the relation between
    type of the baked expression, the pixel type for canvases, and the type name of constants.
  • The MDL SDK is now also available via vcpkg.
  • Added support for the manifest mode of vcpkg.
  • The performance of editing database elements in general has been improved.
  • The public API requires now C++ 11. All code paths for C++ 03 have been removed.
  • The performance of the module builder has been improved.
  • When exporting textures, the gamma value is now exported as metadata
    (if supported by OpenImageIO and the underlying image file format).
  • The cmake option MDL_BUILD_WITHOUT_CUDA_DRIVER has been added to support building
    the MDL SDK on machines without a CUDA driver being installed.
  • The recommended/tested thirdparty software versions are now:
    • vcpkg: git hash 821100d96.
    • SWIG: 4.2.1.
    • Windows SDK: 10.0.22621.0 or newer.
    • It is now recommended to install the Vulkan SDK also via vcpkg.
  • Support for the install target has been improved. In most cases it is no longer
    necessary to set LD_LIBRARY_PATH/PATH and/or MDL_SAMPLES_ROOT
    for running the examples or tools from an installed location. The executables
    of the CUDA-based examples also no longer depend on the CUDA SDK, only on the
    CUDA driver.
  • With MDL 1.10, a new lookup table for the “Microflake Sheen BSDF” was introduced.
    If not yet supported, integrations need to handle these new 3D RGB textures.
  • Python Bindings:
    • Added get_data_numpy() to access texture tile data with numpy.
    • Renamed internal binding functions to start with an underscore.
    • Added type annotations to structure fields.
    • Updated to Swig to version 4.2.1.
    • Added binding for new IBaker::bake_texture_with_constant_detection function.

• MDL Compiler and Backends

  • Added support for MDL 1.10.
  • Added expression promotion for default arguments of imported entities: Before this release,
    an exported entity was bound to the language versions that are supported by the used types
    in its signature and the called entities in its default arguments; The last restriction is
    now partly lifted: The compiler can now promote expressions from MDL version N to MDL
    version M if N > M. This allows to import entities from older MDL versioned modules in to
    newer ones, even if they use expressions in its default arguments that are not available in
    the new version. The compiler rewrites those expressions with an equivalent expression for
    the current version (just as it is done in the internal representation).
    • Note that this works only for imports from older modules, imports from newer modules to
      older modules still might be filtered out if default expressions does not exists in the
      older version, because there is not always a downgrade path.
    • Note further that this is supported for all MDL versions, not only MDL 1.10 now, so
      exports can create code that is not accepted by older versions of the MDL SDK/compiler.

• MDL Distilling and Baker

  • Added support for baking float2 and float4 expressions.
  • Increased the number of texture spaces supported to 16.
  • Added a NaN-check so resulting pixel values equal to NaN will be replaces by zero.
  • Both, CPU and GPU bakers, implement a new method
    IBaker::bake_texture_with_constant_detection(). This method is an improved version of
    bake_texture() that detects constant textures.

• MDL SDK examples

  • Third-party dependencies:
    • Updated ImGui to version 1.95.5.
    • Added modification markers to the changes made in ImGui.
    • Added modification markers to the changes made in fx-gltf.
    • Updated the d3dx12.h license to match the one of the origin (still MIT).
  • MDL Content:
    • Updated the formatting and some range annotations in the glTF support module.
  • MDL SDK df_native Example:
    • Added support for user defined argument blocks.
    • Added GUI for interactively change material parameters and displaying renderings
      statistics.
    • Using Class Compilation as default. Command line option “--cc” has been deprecated,
      and “--nocc” has been added to force Instance Compilation.
  • Core API / MDL SDK code_gen Example:
    • Also dump render state usage with option “-dump-meta-data”.
  • MDL SDK Example Distilling:
    • Added option “--no_constant_detection”. By default (i.e. “--no_constant_detection”
      not set), the distilling example detects baked textures containing a constant color and
      falls back to baking a constant instead. If the option “--no_constant_detection” is
      set, then the example does not attempt to detect constant colors in the baked textures.
  • MDL SDK Example DXR:
    • Added support for the KHR_materials_anisotropy glTF extension.
    • Updated d3dx12.h to the latest version.
    • Updated fx-gltf to version 2.0.0 and the corresponding nlohmann/json to version 3.11.3.
    • The ICompiled_materials are now dumped in addition to shaders when running with
      “--gpu_debug”.
    • Generated MDL code, from MaterialX, is now also dumped formatted for better readability
      when running with “-g”.
  • Vulkan Examples:
    • The examples use vcpkg for building now and don’t need the Vulkan SDK anymore.
    • Added option for selection a specific GPU.
    • Added SPIR-V optimization and option to disable it.
  • MDL SDK Example df_vulkan:
    • It now uses and requires VK_EXT_descriptor_indexing for unsized and partially filled
      texture arrays in the MDL renderer runtime. This eliminates the need for the indirection
      through the texture index buffer in the old implementation.
    • It now uses the single-init mode.
    • Added GUI for changing display settings and material parameters, and displaying
      rendering statistics.
    • Added output of auxiliary albedo_diffuse/glossy and roughness.
    • Added options for v-sync and the texture results cache size.
  • Added new Core API example “df_native” that shows different compilation modes and options
    and how to generate target code for the native backend.
  • Added new Core API example “df_vulkan” for demonstrating generation and usage of
    distribution functions using the GLSL backend in a Vulkan-based path tracer.

Fixed Bugs

• General

  • Fixed export of MDL modules with animated and/or uvtile textures if
    the texture file exists already.
  • Fixed IModule::get_resource() to enumerate resources that appear in bodies and
    temporaries of functions.
  • Fixed resources appearing in expressions returned by Function_definition::get_body()
    and get_temporary().
  • Fixed some sources of duplicated log warnings.
  • Fixed missing filenames in ILight_profile::get_filename() and
    IBsdf_measurement::get_filename() if the resource resides in an MDL archive or MDLE file.
  • base.mdl: Avoid undefined behavior by skipping tangent updates when this would cause
    a division by zero.
  • Fixed IExpression_factory::create_direct_call() to support
    temporary references as arguments.
  • When creating MDLEs of variants, the ::anno::origin annotation now points to the
    variant itself, not to its prototype.
  • Fixed names of some unit test targets to support the cmake generator for Ninja.
  • Fixed documentation for the ::base and ::nvidia::core_definitions modules to match
    exactly the version of those modules.

• MDL Compiler and Backends

  • Skip transmission check for thin-walled materials in target material mode, because the
    analysis is only supported with the material constructor as a root of the compiled material.
  • Fixed inserting unnecessary decl_cast when the root of the compiled material already had
    the correct type. This broke the target material mode, always resulting in a material
    constructor.
  • Fixed wrong error message when a material and sub types are used as parameters
    for declarative functions.
  • Functions used inside default argument expressions of struct constructors are now
    auto-imported.
  • Fixed several conditions under which an auto-import of default arguments has failed.
  • Fixed missing state usage information for distribution functions and for all functions
    compiled in single-init mode.
  • Fixed handling of material parameters and read-only data constants requested as derivative
    values by functions.

• MDL Distiller and Baker

  • Fixed the baking of varying boolean expressions.
  • Fixed distiller implementation to enable distilling with
    the MDL core library (libmdl_core).

• MDL SDK examples

  • glTF Support:
    • Fixed tangent rotation for normal map lookups.
  • MDL SDK Example DXR:
    • Fixed MaterialX version detection to determine if the target version option
      is supported.