Sharing Physically Based Materials Between Renderers with MDL

Transcription

1 Sharing Physically Based Materials Between Renderers with MDL Jan Jordan Lutz Kettner Software Product Manager MDL Director Advanced Rendering and Materials October 10, GTC Europe 2018

2 Introduction to NVIDIA Material Definition Language MDL Agenda Matching the appearance of a single material within different rendering techniques Defining physically-based materials MDL ecosystem Become part of the ecosystem 2

3 Introduction 3

4 The NVIDIA Material Definition Language (MDL) is technology developed by NVIDIA to define physically-based materials for physically-based rendering solutions. 4

5 Iray Photoreal 5

6 Iray Photoreal 6

7 Iray Photoreal 7

8 courtesy Harley Davidson 8

9 9

10 10

11 11 NVIDIA vmaterials with Iray Photoreal

12 Iray Photoreal 12

13 Matching the Appearance of a Single Material Within Different Rendering Techniques 13

14 One Scene for Different Renderers Realtime Rasterizer Interactive Raytracer Pathtracer Share scene and MDL materials for a consistent look Switching renderers with no scene modifications 14

15 Iray Photoreal Path Tracer Iray Interactive Ray Tracer, Direct Illumination Iray Realtime 15 OpenGL Rasterizer

16 Traditional Shading Language Parts Texturing Material Definition Material Implementation Texture lookups Procedurals Uv-transforms Projectors Noise functions Math functions Glossy reflection Transparency Translucency Light loops / trace N rays OIT / ray-continuation Ray marching 16

17 Renderer Procedural Programming Language Texture lookups Procedurals Uv-transforms Projectors Noise functions Math functions Declarative Material Definition Glossy reflection Transparency Translucency Rasterizer Light loops / OIT Trace N rays Raytracer Pathtracer Ray-marching 17

18 Renderer Procedural Programming Language Declarative Material Definition Rasterizer Light loops / OIT Raytracer Trace N rays Pathtracer Ray-marching 18

19 Renderer Procedural Programming Language Declarative Material Definition Rasterizer Light loops / OIT MDL is not a Shading Language MDL defines what to compute, not how to compute it no programmable shading no light loops or access to illumination no trace call no sampling no camera dependence Trace N rays Raytracer Pathtracer Ray-marching 19

20 MDL Material Model material surface volume geometry backface 20

21 MDL Material Model material surface volume geometry bsdf scattering backface 21

22 MDL Material Model material surface volume geometry bsdf scattering emission edf emission intensity backface 22

23 MDL Material Model material surface volume geometry bsdf scattering emission edf backface emission intensity vdf scattering scattering_coefficient absorption_coefficient 23

24 MDL Material Model material surface volume geometry bsdf scattering vdf scattering displacement emission edf emission intensity scattering_coefficient absorption_coefficient cutout_opacity normal backface 24

25 MDL Material Model material surface volume geometry bsdf scattering vdf scattering displacement emission edf emission intensity scattering_coefficient absorption_coefficient cutout_opacity normal backface ior thin_walled 25

26 MDL Bidirectional Scattering Distribution Functions Elemental Distribution Functions Diffuse Reflection Diffuse Transmission Glossy (various) Backscatter Glossy Specular Reflection Spec. Refl.+Transm. Measured BSDF 26

27 MDL Emissive Distribution Functions Elemental Distribution Functions Volume Distribution Functions Diffuse Spot IES Profile Henyey-Greenstein 27

28 MDL Distribution Function Modifiers Tint Thin Film Directional Factor Measured Curve Factor 28

29 MDL Distribution Functions Combiners Normalized Mix Clamped Mix Weighted Layer Fresnel Layer Custom Curve Layer Measured Curve Layer 29

30 MDL 1.4: Modifier: Complex ior factor New BSDF Copper Gold Silver Combiners: All weights can be color now Custom curve layer 30

31 MDL Layered Material Example 31

32 Defining Physically-based Materials With Source Code 33

33 Defining a Material Using MDL MDL is a C like language. The material viewed as a struct struct material { bool material_surface material_surface color material_volume material_geometry }; thin_walled; surface; backface; ior; volume; geometry; 34

34 Defining a Material Using MDL MDL is a C like language. The material and its components viewed as a struct struct material { bool material_surface material_surface color material_volume material_geometry }; thin_walled; surface; backface; ior; volume; geometry; struct material_surface { bsdf material_emission }; scattering; emission; 35

35 Defining a Material Using MDL MDL is a C like language. The material and its components viewed as a struct struct material { bool thin_walled = false; material_surface surface = material_surface(); material_surface backface = material_surface(); color ior = color(1.0); material_volume volume = material_volume(); material_geometry geometry = material_geometry(); }; struct material_surface { bsdf scattering = bsdf(); material_emission emission = material_emission(); }; 36

36 Defining a Material Using MDL Material struct is already fully defined material(); 37

37 Defining a Material Using MDL Material struct is already fully defined material(); 38

38 Defining a Material Using MDL Creating new materials material name ( material-parameters ) = material ( material-arguments ); 39

39 Defining a Material Using MDL material plaster( ) = material( surface: material_surface( scattering: df::diffuse_reflection_bsdf() ) ); 41

40 Defining a Material Using MDL New materials can have parameters material plaster ( color plaster_color = color(.7)) = material( surface: material_surface ( scattering: df::diffuse_reflection_bsdf ( tint: plaster_color ) ) ); 42

41 Defining a Material Using MDL Create complex materials by layering material plastic( color diffuse_color = color(.15,0.4,0.0), float roughness = 0.05 ) = material( surface: material_surface( scattering: df::fresnel_layer ( ior: color(1.5), layer: df::simple_glossy_bsdf ( roughness_u: glossy_roughness ), base: df::diffuse_reflection_bsdf ( tint: diffuse_color ) ) ) ); 43

42 MDL Handbook Added displacement since 2017 Cloth example 4 anisotropic glossy highlights + translucency 44

43 MDL Procedural Programming Language C-like language for function definitions Function results feed into material and function parameters Shader graphs are equivalent to function call graphs texture_coordinate texture_space`: 0 summed_perlin_noise position color_constructor value Material plaster plaster_color 45

44 Defining a Function Using MDL MDL is C like type-of-return-value function-name ( parameters ) { statements } 46

45 Defining a Function Using MDL Function access render state through standard modules color uv_as_color() { return color( state::texture_coordinate(0) ); } 47

46 Defining a Function Using MDL Use functions to drive BSDF or material parameters color uv_as_color() { return color(state::texture_coordinate(0)); } material uv_as_color_material_v2() = plaster( plaster_color: uv_as_color() ) 48

47 Defining a Function Using MDL Functions allow control flow like loops, switches, conditionals float summed_perlin_noise ( float3 point, int level_count=4, float level_scale=0.5, float point_scale=2.0, bool turbulence=false) { float scale = 0.5, noise_sum = 0.0; float3 level_point = point; for (int i = 0; i < level_count; i++) { float noise_value = perlin_noise(level_point); if (turbulence) noise_value = math::abs(noise_value); else noise_value = * noise_value; noise_sum += noise_value * scale; scale *= level_scale; level_point *= point_scale; } return noise_sum; } MDL Handbook 49

48 Defining a Function Using MDL Call graph of functions substitute shader graphs material perlin_noise_material() = plaster( plaster_color: color( summed_perlin_noise( point: state::texture_coordinate(0) ) ) ) texture_coordinate texture_space`: 0 summed_perlin_noise position color_constructor value Material plaster plaster_color 50

49 MDL Module System MDL is program code MDL is a programming language allowing dependencies among modules and materials import nvidia::vmaterials::design::metal::chrome::*; We use search paths to resolve imports 51

50 MDL Module System MDL is program code MDL is a programming language allowing dependencies among modules and materials import nvidia::vmaterials::design::metal::chrome::*; We use search paths to resolve imports C:\Users\Jan\Documents\mdl\nvidia\vMaterials\Design\Metal\chrome.mdl search path MDL package space nvidia::vmaterials::design::metal::chrome 52

51 UDIM and uv-tiles New in MDL 1.4 UDIM texture layout in Autodesk Maya, rendering in Iray 53

52 Additional MDL Benefits Measured Materials Designed for Parallelism Material Catalogs Spatially Varying BRDF AxF from X-Rite Measure Isotropic BSDF Little data dependencies Side-effect free functions Modules and packages Archives 54

53 MDL Ecosystem 55

54 MDL Past, Present and Future MDL 0.x MDL 1.0 MDL 1.1 MDL 1.2 MDL 1.3 MDL 1.4 MDL 1.5 Public Specification vmaterials Advisory Council JIT Compile Public SDK Iray 2013 Nvidia Iray Plugins Holodeck Open Source SDK Bunkspeed mental ray (3ds May, Maya) Substance Designer Unreal Studio 4.20 Catia V6 Vray Adobe Dimension Daz 3d ESI IC.IDO Solidworks Visualize

55 MDL Advisory Council Companies sharing our vision of MDL Joint direction of MDL and the MDL eco system Include expertise other companies have gained in the field and with MDL 57

56 MDL Ecosystem Creation Rendering Applications integrating Renderers Substance Designer Chaosgroup Vray Adobe Dimensions Vray Max/Maya Libraries UE4 Unreal Studio NVIDIA Holodeck NVIDIA VMaterials Siemens NX11 Solidworks Vis. Substance Source NVIDIA Iray Dassault Catia V6 Iray DCC Plugins Other Iray Products Adobe Stock Patchwork 3D Daz 3D Studio 58

57 MDL in VRAY 61

58 MDL Adobe Dimension and Adobe Stock 62

59 MDL in Substance Designer 63

60 MDL in Substance Designer 64

61 MDL in Substance Designer 65

62 MDL in Substance Designer 66

63 MDL in Substance Designer 67

64 MDL in Substance Designer 68

65 MDL in Substance Designer 69

66 MDL in Substance Designer 70

67 Focus on Material Exchange Freely choose where to author material content create Substance Designer Iray for Rhino modify Chaosgroup V-RAY consume 71

68 NVIDIA vmaterials 1.5 ~1600 MDL materials verified for accuracy - FREE TO USE 72

69 NVIDIA vmaterials 1.5 More flexible and user-centric parameters 75

70 Become Part of the Ecosystem 76

71 Become Part of the Ecosystem Integrate MDL enabled renderer MDL is included Write your own compiler Based on the freely available MDL Specification Use the MDL SDK Published under the NVIDIA Designworks License and 77

72 Write Your Own Compiler MDL Specification Language specification document Free to use MDL conformance test suite Syntactic conformance tests Semantic conformance tests Available on request 78

73 RENDERING PHYSICS Iray SDK OptiX SDK MDL SDK NV Pro Pipeline vmaterials PhysX VOXELS VIDEO MANAGEMENT GVDB Voxels VXGI GPUDirect for Video Video Codec SDK GRID SW MGMT SDK NVAPI/NVWMI DISPLAY Multi-Display Capture SDK Warp and Blend 79

74 MDL SDK Features MDL source MDL 1.4 Resolve, parse, store MDL SDK DB for MDL definitions DAG view on materials several compilation modes MDL editing Code generators PTX, LLVM IR, x86, GLSL (s. only) Distiller and texture baker Editor Renderer Generate code Bake textures Database of content Compile Material Optimized DAG view on material Samples Samples Documentation and tutorials API Distill Docs 80

75 MDL SDK 2018 What is New Features MDL 1.4 support Class compilation support in all modes Link mode Full material compilation with BSDF reference implementation Improved distilling quality Flexible render state binding in backends MDL archive access accelerated API to enumerate all dependent resources Access to SDK version at API entry point Auto shutdown SDK helper class for simplified access to annotations New samples for all back-ends Samples reorganized CMake build for samples 81

76 MDL and RTX Materials tricky for todays game engines become feasible with RTX Anisotropic glossy reflections True refractive and volumetric materials Measured BRDF Proper translucency Complex glossy lobe shape and color MDL materials make RTX shine! 82

77 MDL SDK and RTX The MDL SDK directly generates code for use in RTX enabled renderer MDL SDK generates PTX material code suitable to be called by OptiX and used with RTX available since MDL SDK Sample program available as part of Optix 5.1 MDL SDK will generate HLSL material code suitable to be used in an DXR based renderer (upcoming feature) Integrating MDL with an RTX based renderer is simple! 83

78 MDL in Realtime Rendering Three approaches 1. Ubershader 2. Compilation: on-demand shader generation 3. Distillation to fixed material model All based on MDL SDK 86

79 Distillation to Fixed Material Model MDL Material Complex BSDF layering Complex procedurals Distillation Fixed Material Model Simple BSDF structure One texture per parameter 88

80 Distillation to Fixed Material Model MDL Material Complex BSDF layering Complex procedurals Distillation Fixed Material Model Simple BSDF structure One texture per parameter bsdf bsdf bsdf bsdf bsdf bsdf bsdf 89

81 Distillation to Fixed Material Model MDL Material Distillation Fixed Material Model Complex BSDF layering Complex procedurals Simple BSDF structure One texture per parameter bsdf tex Material diffuse bsdf bsdf bsdf bsdf tex tex tex tex specular glossy kurtosis normal bsdf bsdf 90

82 Distillation to Fixed Material Model MDL Material Distillation Fixed Material Model Complex BSDF layering Complex procedurals Simple BSDF structure One texture per parameter bsdf bsdf bsdf bsdf bsdf bsdf bsdf tex tex tex tex tex Material diffuse specular glossy kurtosis normal Approximate render result: Some materials will look quite different 91

83 Distillation to Fixed Material Model MDL Material Distillation Fixed Material Model Complex BSDF layering Complex procedurals Simple BSDF structure One texture per parameter bsdf bsdf bsdf bsdf bsdf bsdf bsdf Fast projection of material instances: Realtime editing tex tex tex tex tex Material diffuse specular glossy kurtosis normal Approximate render result: Some materials will look quite different 92

84 Distillation to Fixed Material Model MDL Material Distillation Fixed Material Model Complex BSDF layering Complex procedurals Simple BSDF structure One texture per parameter bsdf bsdf bsdf bsdf bsdf bsdf bsdf Fast projection of material instances: Realtime editing tex tex tex tex tex Flexible framework to target different fixed models not a fixed MDL subset (no MDL lite ) Material diffuse specular glossy kurtosis normal Approximate render result: Some materials will look quite different 93

85 Distillation to Fixed Material Model Results on vmaterials diffuse-only Fresnel( glossy, diffuse) original 94

86 MDL Distilling Released as part of Iray/MDL SDK Example: UE4 target with clearcoat and transparency through alpha GLSL rendering sample using Distilling and baking MDL UE4 95

87 May the Source Be with You Feature image courtesy of Adobe, created by art director Vladimir Petkovic. 96

88 May the Source Be with You NVIDIA Open Sources the MDL SDK Feature image courtesy of Adobe, created by art director Vladimir Petkovic. 97

89 May the Source Be with You NVIDIA Open Sources the MDL SDK BSD 3-clause license Full MDL SDK 48 modules, 570 files, 310 KLOC Excluding MDL Distilling and texture baking GLSL compiler back-end Added MDL Core API Includes MDL Core Definitions and more Feature image courtesy of Adobe, created by art director Vladimir Petkovic. 98

90 MDL Core API A Lower-level Compiler API in the MDL SDK MDL SDK API Higher-level API for easy integration Reference counted interfaces Mutable objects In-memory store Texture and resource importer MDL Core API API close to the compiler Objects managed in arenas Immutable objects Stateless compiler Callbacks 99

91 MDL Takeaways What is MDL MDL Ecosystem Starting Material Declarative Material Definition Procedural Programming Language NVIDIA vmaterials MDL Advisory Council Open Source release MDL Specification MDL Handbook MDL SDK MDL Backend Examples Conformance Test Suite 100

92 Further Information on MDL raytracing-docs.nvidia.com/mdl/index.html Documents NVIDIA Material Definition Language Technical Introduction Material Definition Language Handbook NVIDIA Material Definition Language Language Specification On-Demand 101