MDL SDK 2024.1 (381500.2959): 14 Jan 2025

ABI compatible with the MDL SDK 2024.1 (381500.2959) binary release
(see https://developer.nvidia.com/mdl-sdk)

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
  ...

MDL SDK 2024.0.4 (377400.3959): 07 Oct 2024

ABI compatible with the MDL SDK 2024.0.4 (377400.3959) binary release
(see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.9 Language Specification

  • Updated to document version 1.9.2.

• General

  • The default value for the backend option enable_exceptions is now off,
    as this is the behavior described by the MDL specification.

• MDL Compiler and Backends

  • Implemented folding of ::tex function calls with invalid textures on the DAG.
  • Added “max_const_data” backend option to limit the size of global constants in the
    generated code when the “enable_ro_segment” option is enabled. Larger constants are put
    into read-only data segment. The default is “1024” bytes, which corresponds to
    the old behavior.

• MDL SDK examples

  • MDL Core code_gen example:
    • Added support for single-init mode.
  • MDL SDK df_vulkan example:
    • Added support for read-only data segments and max_const_data backend option.
  • MDL Example Execution Native:
    • It now supports the -p abbreviation for –mdl_path as in all other examples.
  • MDL Example df_native:
    • Added support for argument blocks in Class Compilation mode.
    • Added OpenGL GUI for editing material parameters and displaying stats during rendering.
    • Changed default compilation mode to Class Compilation.
    • Removed command line option --cc which is now replaced
      by --nocc (or disable Class Compilation mode).

Fixed Bugs

• General

  • libbsdf: Fixed issues for df::thin_film over df::custom_curve_layer and
    df::directional_factor with normal reflectivity approaching zero.
  • Fixed a build error if image plugins are disabled.
  • Fixed a build error caused by picking up LLVM header files from a different location.
  • Fixed documented return codes for IExpression_factory::create_cast() and
    create_decl_cast() (error codes are negative as usual, not positive).
  • Fixed missing build dependencies for the distiller plugins and the distiller example plugin.

• MDL Compiler and Backends

  • Allow material sub structs to be used inside a declarative struct and declarative functions.
  • Improved error message in case a select operator cannot be executed because of the
    left-hand-side type was not imported.
  • Fixed wrong HLSL/GLSL read functions used for shadow copies of function parameters.
  • Fixed crash when compiling a function which receives a material parameter but doesn't
    use the state (GLSL backend with rodata segment disabled).
  • Avoid undefined behavior with "%" operator for negative values for GLSL
    by implementing “a % b” as “a - (a / b) * b”.
  • Report when a standard library module is imported with a weak relative import names from
    a module in a search path root. This is needed because standard library modules are
    loaded from a high-priority search path and would shadow any relative import. This will
    trigger a warning for MDL versions between 1.6 and 1.9, and an error for MDL versions
    greater than 1.9.
  • Fixed the documentation of the backend option "hlsl_use_resource_data" and
    "glsl_use_resource_data". These are recognized but not supported at the moment.
  • Fixed compilation of calls to non-inlined functions which receive material parameters as
    arguments for GLSL/HLSL.
  • Return identity matrix instead of zero for unimplemented tex::grid_to_object_space().
  • Fixed crash when compiling an expression as const which only becomes const after
    optimization (e.g. by getting rid of state access).
  • libbsdf: Fixed wrong shadow mask in microfacet BSDFs.
  • libbsdf: Avoid NaNs due to out-of-range roundings during random number updates.
  • MDL Core: Fixed resource indices for native code if a custom texture runtime is used.
  • Fixed crashes if a non-constant default constructor occurred during code generation
    in various backends.

MDL SDK 2024.0.2 (377400.2626): 07 Aug 2024

ABI compatible with the MDL SDK 2024.0.2 (377400.2626) binary release
(see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General
  • MDL Arnold: Added support for Arnold SDK version 7.3.2.1.

Fixed Bugs

• General

  • Fixed missing leading "::" for qualified names reported by IMdl_discovery_api,
    if search paths had a trailing OS separator.
  • Improved error message that can be triggered when calling non-const methods
    on const objects. This can e.g. be triggered via the Python binding by accessing
    (not editing) database elements.
  • Improved coverage tests for the Python binding.

• MDL Compiler and Backends

  • Fixed crash in some cases when derivatives were calculated for a struct also containing
    non-floating point fields.
  • Fixed wrong digit that can be added to tex::texture_isvalid() calls for
    HLSL and GLSL backends, if more than one texture type (for instance texture_2d and
    texture_3d) are used together in one module.

MDL SDK 2024.0.1 (377400.2109): 18 Jul 2024

ABI compatible with the MDL SDK 2024.0.1 (377400.2109) binary release
(see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.9 Language Specification

  • Updated version to 1.9.
  • declarative and struct_category as new reserved words.
  • Added the concept of declarative structure definitions with
    and without a structure category to the conventional
    structure definitions.
  • Added the definition for the assignment operator (=) for
    declarative structs with and without a structure category.
  • Restricted the type cast operator on structure types to
    conventional structure types.
  • Added declarative functions.
  • Restricted overload resolution on material definitions.
  • Extended overload resolution to define functions whose signature
    is a prefix of others as more specific.
  • Specified that function overload sets can contain both
    declarative and non-declarative functions.
  • Clarified that the auto return type for functions is allowed
    on function definitions and not on function declarations.
  • Defined material definitions as functions returning a declarative
    structure definition of the material_category structure category.
  • Defined the builtin material type as a declarative structure type
    with the material_category structure category.
  • Changed the ior field of the builtin material type to
    be of varying type and not uniform color anymore.
  • Defined the builtin distribution function types bsdf,
    edf, vdf, and hair_bsdf as a declarative structure type
    without structure category and without fields.
  • Redefined the compound types in the material type to
    declarative structure types without structure category.
  • Added rounding function round_away_from_zero() and clarified rounding
    behavior of round().
  • Removed the statement for microfacet BSDF models that they become
    black in transmission mode if the ior values indicate total
    interior reflection.

• General

  • The material.ior field is now varying for all versions of MDL (not only for MDL 1.9).
    This avoids to break the ABI to the renderer, since there is still only one material type.
    The new method IMdl_configuration::set_material_ior_frequency() allows to revert
    that change as a workaround for rare compatibility problems with MDL modules authored
    for MDL versions before 1.9. Please note that this will switch the field to uniform
    for all version (including MDL 1.9). Note further that this option cannot be set dynamically,
    it is only possible to set it at SDK start time.

  • Added CMake option MDL_BUILD_SDK which is ON by default. If set OFF
    only the MDL Core and mdlc will be built.

  • The alpha channel is now always treated as linear, independent of the gamma value
    specified for the remaining channels.

  • Added new AOV(Arbitrary Output Variables) support. It allows rendering applications
    to produce customized data in addition to the usual image output buffers:

    • The interface IStruct_category has been added to represent the new
      concept of struct categories. The new interface IStruct_category_list
      represents an ordered collection of struct categories identified by name or index.
    • The new methods IType_struct::get_struct_category() and
      IModule::get_struct_categories() allow to query the struct categories
      of a struct type and those defined in a module, respectively.
    • The new methods IType::is_declarative(),
      IFunction_definition::is_declarative(), and
      Definition_wrapper::is_declarative() indicate whether a type or function is
      declarative.
    • The interface IType_factory has been extended with methods to create,
      clone, compare, and dump struct categories and/or struct category lists.
    • A sixth template-like function, the so-called decl_cast operator, has
      been added. The new method IExpression_factory::create_decl_cast()
      provides a convenient way to create calls of this function definition.
    • The method IMaterial_instance::create_compiled_material() accepts the
      new option "target_type" on the execution context. This option behaves as if
      the entire material is wrapped into a decl_cast operator with the given
      target type.
    • The new method ICompiled_material::get_sub_expression_hash() allows to
      compute hash values of arbitrary sub-expressions and is not limited to
      predefined material slots as ICompiled_material::get_slot_hash().
    • The module builder has been extended to support struct categories: The new
      method IModule_builder::add_struct_category() allows to create them.
      The signature of the method IModule_builder::add_struct_type() has been
      extended with a struct_category parameter. The signature of several
      methods on IModule_builder has been extended with a
      is_declarative parameter. The old signatures are still available if
      MI_NEURAYLIB_DEPRECATED_15_0 is defined.

  • The methods for texture export (IMdl_impexp_api::export_canvas() and
    IImage_api::create_buffer_from_canvas()) and the image plugin API have
    been changed to use a generic options map instead of two hard-coded options.
    Supported options are documented at IImage_api. The old signatures are
    still available if MI_NEURAYLIB_DEPRECATED_15_0 is defined.

  • The new export option "exr:data_type" allows to control the data type of EXR channels.

  • The database supports now multiple scopes. For details, see the
    documentation for the class IScope and the methods create_scope(),
    get_scope(), and remove_scope() on IDatabase.

  • The new method IExpression_factory::create_temporary() allows to create
    temporary references.

  • The signature of IMdl_module_builder::add_function() has been extended
    to support temporaries. The old signature is still available if
    MI_NEURAYLIB_DEPRECATED_15_0 is defined.

  • The free functions set_value() and get_value() on IData
    support now arrays (similar to what existed already for IValue).
    Arrays can be specified as pointer/length pair, or as std::vector.

  • Exit codes in case of array size mismatches for the the free functions
    set_value() and get_value() on IValue have been changed
    from -3 (implementation) and -4 (documentation) to -5 for consistency with
    IData.

  • The methods IModule::get_function_overloads() have been updated to
    implement the modified overload resolution rules for MDL >= 1.9.

  • Additional performance improvements for the creation of compiled materials.

  • The recommended vcpkg version is now 5d675c7e5. This
    changes the recommended versions for Boost to 1.84, OpenImageIO to 2.5.8.0,
    and GLFW to 3.4.

  • The license texts have been split into three separate files
    LICENSE.md, LICENSE_IMAGES.md, and LICENSE_THIRD_PARTY.md.

  • The API reference documentation for the MDL SDK and MDL
    Core is now installed as part of the "install" target.

  • Added the compiler flag -flax-vector-conversions when
    using OpenImageIO on Linux and ARM.

  • Python Bindings:

    • Changed the recommended Python version to 3.10.
    • Improved type hints.
    • Added stub functions to keep the bindings backwards compatible.
    • Prepared for an update to Swig 4.2.1.
    • Added more tests to improve coverage.

• MDL Compiler and Backends

  • Increased default MDL version to 1.9.
  • Added support for MDL 1.9:
    • Implemented math::round_away_from_zero().
    • Implemented structure categories, declarative structures and declarative functions.
    • Adapted overload resolution to new rules.
  • Added backend option "libbsdf_flags_in_bsdf_data" to enable use of the new
    "flags" field in the BSDF data structures for libbsdf. The flags can be used
    to restrict generated sample, evaluate, pdf and auxiliary functions to only
    calculate reflections, transmissions or both.
  • MDL Core API: Support for declarative structs and functions (AOV support).
    • Extend the abstract syntax of MDL
      • New declaration kind mi::mdl::IDeclaration::Kind::DK_STRUCT_CATEGORY and corresponding
        class mi::mdl::IDeclaration_struct_category for struct category declarations.
      • New methods on mi::mdl::IDeclaration_type_struct for modifying a struct's category:
        • IQualified_name const *get_struct_category_name().
        • IDefinition const *get_struct_category_definition().
        • void set_struct_category_definition(IDefinition const *category_definition).
      • New methods on mi::mdl::IDeclaration_type_struct and mi::mdl::IDeclaration_function
        for the declarative flags:
        • bool is_declarative().
        • void set_declarative(bool flag).
      • New and modified methods on mi::mdl::IDeclaration_factory for handling struct categories
        and changes to structs and functions:
        • IDeclaration_struct_category *create_struct_category(...).
        • IDeclaration_type_struct *create_struct(bool declarative = false, ...,
IQualified_name const *category_name).
        • IDeclaration_function *create_function(bool is_declarative, ...).
      • Changes to mi::mdl::IDefinition to support declarative features:
        • New definition kind DK_STRUCT_CATEGORY.
        • New definition flag DP_IS_DECLARATIVE.
        • New intrinsic DS_INTRINSIC_DAG_DECL_CAST.
        • New function IStruct_category const *get_category() to get the category of
          a category definition.
      • Changes to mi::mdl::IGenerated_code_dag...

MDL SDK 2023.1.4 (373000.3036): 18 Mar 2024

ABI compatible with the MDL SDK 2023.1.4 (373000.3036) binary release
(see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Added a linker script on Linux that hides all defined symbols except for the factory symbol(s).

• MDL SDK examples

  • Updated OptiX 7 example to support up to OptiX SDK 8.0.0.
  • Example AXF to MDL
    • Added support for AxF 1.9 sheen for SVBRDF representation.
    • Improved compatibility for refracting carpaint representation.
    • Improved mapping of Cook-Torrance spreads (used for non-measured BRDF fallback
      and flake orientation).
  • Example Execution GLSL:
    • Added enable/disable SSBO and noise function remap by command line arguments.

Fixed Bugs

• General

  • Fixed a crash if IMdl_resolved_resource_element::create_reader() returns nullptr.
    This might be due to an incorrect user implementation, or in legitimate cases, e.g.,
    if the file disappeared between resolving and the query.
  • Fixed a memory leak involving the interface pointer used with the context option
    "user_data".

• MDL Compiler and Backends

  • Fixed inconsistent storing and reading of matrix material parameters in target
    argument blocks for the native backend.
  • Avoid warnings about unsupported PTX features for native backend.
  • Don't let LLVM abort at shutdown, when writing to stderr fails.
  • mdltlc: Fixed error in pattern matching of material nodes.
  • Fixed HLSL/GLSL code generation that sometimes placed temporaries into a
    loop body that are used outside, causing invalid code.
  • Fixed crash in the core compiler that might happen on heavily malformed MDL code.
  • Prevent errors/warnings in the core compiler without line numbers
    due to internal clone operations.
  • Slightly speedup compilation in multithreaded operations.
  • Do not try to resolve empty resource URLs; Note that this is still malformed MDL code.

• MDL SDK examples

  • Example df_vulkan
    • Fixed command line options to match other examples for --mdl_path / -p option.
  • Example AXF to MDL
    • Fixed re-coding of BRDF colors table (used in non-measured BRDF fallback).
  • Example Execution GLSL:
    • Fixed OpenGL 3.3 mode.

MDL SDK 2023.1.3 (373000.2208): 14 Feb 2024

Added and Changed Features

• General

  • Update to zlib 1.3.1.

• MDL SDK examples

  • Example AXF to MDL
    • Simplified the code that constructs an instance of the spectral color constructor. This
      also demonstrates how to use the Argument_editor to set array arguments.

Fixed Bugs

• General

  • Fixed IMdl_factory_impl::get_db_definition_name() for entities from the ::<builtins>
    module.
  • Fixed export of MDL modules with uvtile and/or animated textures, where under certain
    conditions the first tile/frame was repeated for all tiles/frames of a particular resource
    set.
  • Fixed a bug that caused DB changes to become visible in concurrent transactions.
  • Fixed missing dependencies on libdl on Linux that triggered the recently added undefined
    symbol check on Ubuntu 20.04.

• MDL Compiler and Backends

  • Fixed indeterministic generation of rmem* variables for HLSL/GLSL.
  • Fixed invalid HLSL/GLSL code generation.

• MDL SDK examples

  • Example Distilling Target
    • Visual Studio project names for the executable and library use now different names.

MDL SDK 2023.1.2 (373000.1755): 23 Jan 2024

ABI compatible with the MDL SDK 2023.1.2 (373000.1755) binary release
(see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • libbsdf:
    • The roughness values computed by the generated auxiliary functions changed to contain
      only glossy contributions.
    • The color weights for normals and roughness in the generated auxiliary functions
      are now reduced by luminance instead of average.

• MDL Compiler and Backends

  • Allow more direct assignments of vectors instead of element-wise assignments for HLSL.
  • Avoid unnecessary calls to functions whose values are not actually used.
  • Avoid reading whole arrays from argument blocks or read-only data segments when
    providing those arrays as function parameters. This especially improves rendering
    performance of axf_importer materials.
  • Avoid array copies when accessing arrays provided as function parameters for HLSL/GLSL.

• MDL SDK examples

  • Add options to configure the lambda return mode and the generation of PDF and auxiliary
    functions to code_gen example.
  • Rename "-p" parameter of df_cuda example to "--cam" and use "-p" as short form
    for "--mdl_path" as in other examples.

Fixed Bugs

• General

  • nvidia::core_definitions: Fixed '--' in display names.
  • Fixed type computation of ternary operator in MDL SDK/neuray.

• MDL Compiler and Backends

  • Fixed a rare crash that could happen in an MDL module imports other modules and
    import the same module (diamond pattern).
  • Fixed default constructor of enum values which sometimes did not choose
    the first enumerator as default value.

MDL SDK 2023.1 (373000.1077): 14 Dec 2023

ABI compatible with the MDL SDK 2023.1 (373000.1077) binary release
(see https://developer.nvidia.com/mdl-sdk)

Known Issues and Restrictions

• MDLE export can fail in this release with broken .mlde files that contain malformed MDL code.

Added and Changed Features

• General

  • Added rotate_around_x/y/z functions to ::nvidia::support_definitions.
  • The MDL SDK comes now with unit tests. Building of the unit tests is
    controlled via the cmake option MDL_ENABLE_UNIT_TESTS. Unit
    tests can be executed from the command line via CTest, make test,
    or the Visual Studio solution. Some unit tests require the idiff
    tool from OpenImageIO.
  • The baker uses now multiple threads.
  • The deprecated FreeImage plugin as been removed.
  • The recommended vcpkg version has been updated. It is now also
    recommended to install GLEW and GLFW via vcpkg. The
    feature flag tools for OpenImageIO is now required by some
    unit tests.
  • The database used by the MDL SDK supports now multiple parallel
    transactions. See the documentation of ITransaction for visibility
    and conflict resolution. This change includes adding support for
    ITransaction::abort(). As a consequence, if an ITransaction is
    released without committing or aborting, it is now automatically aborted
    with a warning instead of being committed with an error message.
  • The new API component ILogging_configuration has been added to the
    MDL SDK. The API methods IMdl_configuration::set_logger() and
    get_logger() have been deprecated. Use
    ILogging_configuration::set_receiving_logger() and
    ILogging_configuration::get_receiving/forwarding_logger() instead. The
    old methods are still available if MI_NEURAYLIB_DEPRECATED_14_1 is
    defined. Use ILogging_configuration::set_log_prefix(0) to prevent
    the forwarding logger from automatically adding the severity to the log
    message.
  • Additional performance improvements, in particular with a focus on
    creation of compiled materials.
  • The new methods IType_factory::get_mdl_type_name() and
    create_from_mdl_type_name() allow to serialize and deserialize types via
    their type names.
  • The new method IType_factory::get_mdl_module_name() returns the
    name of the MDL module that defines a given type. This is primarily
    useful for enum and struct types.
  • The method IType_array::get_deferred_size() returns now the
    "simple" symbol name, e.g., "N" instead of the fully qualified one.
  • The method IExpression_factory::create_direct_call() allows now to
    create calls to unexported functions. Note that such calls can only be
    used in the same module as the called function.
  • When loading textures via an MDL module, failures do no longer cause a
    dummy instance of ITexture to be created and
    IValue_texture::get_value() returns now a NULL pointer.
  • Python Bindings:
    • Added more missing interface functions to the bindings.
    • Removed all generated "declare_interface"-types.
    • Added post build step to strip unused types and functions and
      marked constructors invalid.
    • Fixed "error"-out-parameters by providing a ReturnCode type that can be passed
      by reference.
    • Added UUID comparison for interface types.
    • Updated the binding of enums which are now Python enums in the appropriate scope.
    • Extended unit tests written in Python.
    • Added a coverage report option for the unit tests written in Python.
    • Added missing and fixed existing get/set_value functions for various IData class bindings.
    • Mapping now mi::Size to Sint64 to handle -1 returns correctly.
    • Removed the IAttribute_set function from scene elements.

• MDL Compiler and Backends

  • Removed unused exception_state parameter from generated functions for non-native backends
    to improve performance. Needs update in renderers calling these functions.
  • Let generated functions for material expressions of base types and vector types return
    their values directly instead via a result buffer by setting the new backend option
    "lambda_return_mode" to "value". Only supported by the PTX and the LLVM-IR backend.
  • Generated auxiliary functions now separate albedo into diffuse and glossy, similar to the evaluate functions.
  • Generated auxiliary functions now also report roughness.

• MDL Distiller and Baker

  • Debugging features for mdltlc: debug_name and debug_print statements
    in MDLTL rules files.
  • Added mdltl unit tests.

• MDL SDK examples

  • Replaced compiler define NO_DIRECT_CALL by command line parameter
    --use-direct-call to make it easier to try both variants.
  • Adapted MDL SDK df_cuda and OptiX 7 examples to use the new value return mode.
    The MDL Core df_cuda example still uses the old default mode ("sret").
  • AxF Example:
    • Updated to Pantora 1.9.0.
    • Added search path command line options.
  • Example DXR:
    • Changed hardware sampler mode to clamp and implemented repeat by software
      to fix edge cases when cropping.
    • Added a MaterialX to MDL version number parameter in preparation for
      upcoming MaterialX releases.
    • Added options to render multiple auxiliary outputs to file in one run.

Fixed Bugs

• General

  • base.mdl:
    • Improved tangent space handling for bump maps. Noise-based bump mapping is now
      oriented correctly for object and world space coordinate sources.
    • Additionally, coordinate transforms change the orientation consistently now.
      This adds one field to base::texture_coordinate_info.
  • Added a work-around to handle user defined constants inside the code that is added using
    add_function() to an existing MDL module in the MDL_module_builder interface.
    This can only handle cases where the user defined type is either defined locally
    or imported using an absolute path.
  • Python Binding: Fixed proxy parameter handling of "IMdl_distiller_api::create_baker"
    and "ILight_profile::reset_*" functions.

• MDL Compiler and Backends

  • Fixed auto-import of enum conversion operators.
  • Fixed a case where the auto-importer was not able to import conversion operators
    (enum-to-int), which caused wrong prefixed constructors when exporting MDL,
    e.g. base::int(value).
  • Adapted data layout for PTX to match data layout used by CUDA compiler
    to avoid problems with misaligned data types.
  • Fixed wrong function indices set for init functions in single-init mode,
    when ILink_unit::add_material() is called more than once.
  • Fixed invalid CUDA prototypes returned by
    mi::neuraylib::ITarget_code::get_callable_function_prototype().
  • Fixed texremapu in base.mdl for GLSL resulting in undefined behaviour
    for negative texture coordinates.
  • Improved handling of invalid MDL code in the MDL compiler.

• MDL Distiller and Baker

  • Fixed printing of NaN, +inf and -inf constants in the mdl_distiller_cli
    command line utility. They are now printed as (0.0/0.0), (1.0/0.0) and (-1.0/0.0)
    respectively, same as in the MDL compiler and SL backends.
  • mdltlc: Fixed code generation for rules with node names.
  • mdltlc: Fixed code generation for creation of conditional expressions.

• MDL SDK examples

  • Example DXR: Fixed resource creation warnings reported with the
    "--gpu-debug" option on Windows 11.

MDL SDK 2023.0.6 (367100.5773): 03 Nov 2023

ABI compatible with the MDL SDK 2023.0.6 (367100.5773) binary release
(see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Various performance improvements, in particular with a focus on creation of
    compiled materials.
  • Python Bindings:
    • Added get and set value functions to the bindings of types in mi::data and
      added corresponding tests.
    • Removed the IAttribute_set interface from the bindings of the IScene_element types.

• MDL Compiler and Backends

  • Optimized high-level (GLSL/HLSL) code generator to reduce code size.
  • Added new backend option "hlsl_remap_functions": This allows to remap MDL functions
    (including state functions) to user implemented Native HLSL implementations.

• MDL Distiller and Baker

  • Renamed mdl_distiller command line tool to mdl_distiller_cli to more
    clearly separate it from the distiller plugin of the same name.

Fixed Bugs

• General

  • Fixed IFactory::compare() for IString and IRef on Linux on ARM.
  • Python Bindings:
    • Fixed the binding for the ITile::get_pixel() and
      ITile::set_pixel() functions.
    • Mapped mi::Size to signed integer in python to allow for
      comparing against -1.
    • Deprecated the tuple return of functions that have an float* out parameter in C++.
      Now an ReturnCode object is passed in and out as Python parameter.
    • Removed unused classes and functions from the bindings.

• MDL Distiller and Baker

  • mdltlc: Fixed matching on nested attribute expressions.
  • Fixed missing enum to int conversion operator an auto-imports,
    which caused compilation errors in rare cases.
  • Fixed context information when compiling entities in the DAG-backend
    (fixes only some asserts in debug mode).
  • Fixed HLSL/GLSL code generation for access to single element compound types,
    like arrays of length 1 or structs with only one field.

MDL SDK 2023.0.4 (367100.4957): 05 Oct 2023

ABI compatible with the MDL SDK 2023.0.4 (367100.4957) binary release
(see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Python Bindings:
    • Added binding for the (built-in) entity resolver and added unit tests.
    • Accessing functions of invalid interfaces do not crash anymore but
      instead throw python exceptions.
    • Added more unit tests.
    • Extend the wrapper around MDL type (Type):
      • Give access to vectors and arrays size and element type.
      • Give access to matrices size.
    • Convert low level IValues to python friendly data types:
      • Extended to give access to file path for textures, light profiles
        and BSDF measurements.

• MDL SDK examples

  • Example DXR:
    • Reduced the HLSL glue code and added dynamic function selection
      for generated shader functions.
    • Added support for backface scattering and emission.
    • Handle meters_per_scene_unit at runtime and expose the parameter to the UI.
    • MaterialX resource resolution now uses the MDL entity resolver as fallback
      to handle tiled resources.
    • Handle the collapse flag of the in_group annotations.
    • Improved measured BSDF runtime implementation numerically.
    • Camera pose fitting now sets near and far plane distances.
    • Added support for KHR_materials_iridescence glTF extension.
  • Example Traversal:
    • Removed the preprocessor directive that disabled the distiller option.

Fixed Bugs

• General

  • Catch memory allocation failures in the OpenImageIO plugin while exporting images.
  • Python Bindings: Fixed the mdl_distiller plugin path in the scripts for
    running the examples.
  • Argument expressions that are created by the API are no longer optimized by the MDL
    compiler, but stay "unmodified" until arguments in class compilation mode are created.
    This makes the generated arguments more "deterministic" for users.
  • Fixed export of uv-tile textures. Only first tile was exported.
  • Fixed export of animated textures when frame number differs from frame ID.

• MDL Compiler and Backends

  • Fixed translation of vector access with non-constant index in some cases for HLSL/GLSL.
  • Fixed bit-operations on integer fields in structs containing derivable values.
  • HLSL/GLSL: The compiler uses now name mangling on struct types instead of
    the very simple old connection with '_'.
  • Fixed bug that caused crashes when several MDL modules import each other
    within a special order.
  • Material expressions which path prefix is "geometry.displacement" are now created in
    the displacement context.
  • Fixed code generation for re-exported MDL entities.
  • Fixed parsing of resource sets inside container files (MDLE).
  • Fixed ownership of types in created distribution functions which could lead to crashes
    under certain complex conditions.
  • Fixed crashes due to "missing functions" which are requested from wrong modules,
    for instance state::cos().
  • Fixed printing of package name components which are MDL keywords and require
    quoting as Unicode identifiers.

• MDL SDK examples

  • Example DXR:
    • Fixed the UI parameter mapping for struct parameters.
    • Reviewed the UV coordinate handling and improved its documentation.
    • Added missing out of bounds check when reading NV_materials_mdl nodes.
    • Treat alpha channels in glTF textures as linear in cases where the RGB data
      is in sRGB color space.