materials/vMaterials_2/Metal/Chromium_Knurling.mdl

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mdl 1.5;

import ::df::*;
import ::tex::*;
import ::math::*;
import ::base::*;
import ::state::*;
import ::anno::*;
import ::nvidia::core_definitions::*;

const string COPYRIGHT =
" Copyright 2024 NVIDIA Corporation. All rights reserved.\n"
" MDL MATERIALS ARE PROVIDED PURSUANT TO AN END USER LICENSE  AGREEMENT,\n"
" WHICH WAS ACCEPTED IN ORDER TO GAIN ACCESS TO THIS FILE.  IN PARTICULAR,\n"
" THE MDL MATERIALS ARE PROVIDED \"AS IS\", WITHOUT WARRANTY OF ANY KIND,\n"
" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF\n"
" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF\n"
" COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL NVIDIA\n"
" CORPORATION BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, INCLUDING ANY\n"
" GENERAL, SPECIAL,  INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WHETHER IN\n"
" AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF THE USE OR\n"
" INABILITY TO USE THE MDL MATERIALS OR FROM OTHER DEALINGS IN THE MDL MATERIALS.\n";

const string DESCRIPTION = "Metal with a diamond knurling finish";

float histogram_range(float input, float range = 1.0f, float position = 0.5f)
{	
	float low = ::math::clamp(1.0 - ::math::min(((1.0 - position) + range * 0.5), (1.0 - position) * 2), 0.0, 1.0);
	float high = ::math::clamp(::math::min((position + range * 0.5 ), position * 2.0), 0.0, 1.0);
	return ::math::lerp(low, high, input);
}

::base::texture_coordinate_info transform_coordinate_2(
	float4x4 transform										 
		[[ ::anno::description("A transformation to be applied to the source coordinates. rotation_translation_scale() is a suggested means to compute the transformation matrix.") ]],
	::base::texture_coordinate_info coordinate = ::base::texture_coordinate_info()
		[[ ::anno::description("Coordinate, typically sourced from coordinate_source or coordinate_projection.") ]]
) [[ 
	::anno::description("Transform a texture coordinate by a matrix.") ,
	::anno::noinline()
  ]]
{
	// Version 2
	float4 r_position = transform * float4(coordinate.position.x,coordinate.position.y,coordinate.position.z,1);
	//Try aproximating it for the case that the rotation is only aroud z and assuming the texture layout is nice and z is ~constant.
	//just pretend there is no other rotation happening
	//get rid of scaling and translation. Then extract fields where sin and cos would be in a simple 2d transform around z.
	float4 u = transform[0];
	float3 ru = ::math::normalize(float3(u.x,u.y,u.z));
	float cos =  ru.x; 
	float sin =  -ru.y;
	//TODO: at least also handle sign of z?
	//TODO: handle tangent becoming 0 
	
	
	return ::base::texture_coordinate_info(
		float3(r_position.x,r_position.y,r_position.z),
		::math::normalize(cos * coordinate.tangent_u - sin * coordinate.tangent_v),
		::math::normalize(cos * coordinate.tangent_v + sin * coordinate.tangent_u));
}

::base::texture_coordinate_info vmat_transform(
								float2 translation = float2(0.0, 0.0),
								float rotation	 = 0.0,				// rotation in degrees
								float2 scaling	 = float2(1.0, 1.0),
								uniform ::base::texture_coordinate_system system = ::base::texture_coordinate_uvw,
								uniform int uv_space	   = 0
)
{
	float rotation_rad = (rotation * 3.1415926535897932384626433832f) / 180.f;
	float4x4 scale =
	float4x4(1.0 /scaling.x, 0.			 ,  0. ,	 0.,
			 0.			, 1.0 /scaling.y ,  0. ,	 0.,
			 0.			, 0.			 ,  1.0,	 0.,
			 translation.x , translation.y  ,  0.0,	 1.);

	float s = ::math::sin(rotation_rad);
	float c = ::math::cos(rotation_rad);
	float4x4 rotate =
	float4x4(  c  ,  -s   , 0.0 , 0.0,
			   s  ,   c   , 0.0 , 0.0,
			   0.0,   0.0 , 1.0 , 0.0,
			   0. ,   0.0 , 0.0 , 1.);
	
	return transform_coordinate_2(scale*rotate, ::base::coordinate_source(system, uv_space));
}

export material Chromium_Knurling(
	//Appearance
	float brightness = float(0.7f) [[
		::anno::description("Adjusts the brightness of the material."),
		::anno::display_name("Brightness"),
		::anno::in_group("Appearance"),
		::anno::hard_range(0.0f, 1.0f)
	]],
	float roughness = float(0.5f) [[
		::anno::description("Higher values lead to a rougher appearance of the material."),
		::anno::display_name("Roughness"),
		::anno::in_group("Appearance"),
		::anno::hard_range(0.0f, 1.0f)
	]],
	float grooves_dirt = float(0.4f) [[
		::anno::description("Adds dirt in the grooves of the knurling pattern."),
		::anno::display_name("Grooves Dirt"),
		::anno::in_group("Appearance"),
		::anno::hard_range(0.0f, 1.0f)
	]],
	uniform float bump_strength = float(0.8f) [[
		::anno::description("Adds dirt in the grooves of the knurling pattern."),
		::anno::display_name("Bump Strength"),
		::anno::in_group("Appearance"),
		::anno::soft_range(0.0f, 1.0f)
	]],
	
	// Round Corners
	uniform bool enable_round_corners = false [[
		::anno::display_name("Enable Round Corners"),
		::anno::in_group("Round Corners")
	]],
	uniform float roundcorner_radius = 0.01f [[
		::anno::display_name("Round Corner Radius"),
		::anno::description("Sets the radius of the round corners in millimeters."),
		::anno::soft_range(0.0f, 0.1f),
		::anno::in_group("Round Corners")
	]],
	uniform bool across_materials = false [[
		::anno::display_name("Across Materials"),
		::anno::description("Applies the rounded corner effect also between other materials."),
		::anno::in_group("Round Corners")
	]],
	//Transform
	float2 texture_translate = float2(0.f) [[
		::anno::description("Controls the position of the texture."),
		::anno::display_name("Texture Translate"),
		::anno::in_group("Transform")
	]],
	float texture_rotate = 0.f [[
		::anno::description("Rotates angle of the texture in degrees."),
		::anno::display_name("Texture Rotate"),
		::anno::in_group("Transform"),
		::anno::soft_range(0.f, 360.f)
	]],
	float2 texture_scale = float2(1.f) [[
		::anno::description("Larger numbers increase the size."),
		::anno::display_name("Texture Scale"),
		::nvidia::core_definitions::dimension(float2(0.35f, .35f)),
		::anno::in_group("Transform"),
		::anno::soft_range(float2(0.f), float2(2.f))
	]],
	
	// Advanced
	uniform int uv_space_index = 0 [[
		::anno::description("Uses the selected UV space index."),
		::anno::display_name("UV Space Index"),
		::anno::in_group("Advanced"),
		::anno::soft_range(0, 4)
	]]
)
[[
	::anno::display_name("Metal Knurling Chromium"),
	::anno::description(DESCRIPTION),
	::anno::copyright_notice(COPYRIGHT),
	::anno::thumbnail("./.thumbs/Chromium_Knurling.Chromium_Knurling.png"),
	::anno::key_words(string[]("metal", "chromium", "knurled", "knurling", "pattern", "design", "bumped")),
	::anno::contributor("Ruediger Raab"),
	::anno::author("NVIDIA vMaterials")
]]
= let
{
	color metal_tint = color(0.549302f, 0.5560554f, 0.5542377f);
	
	// Texture setup
	texture_2d normal_tex = texture_2d("./textures/metal_knurling_norm.jpg", ::tex::gamma_linear);
	texture_2d multi_heights_tex = texture_2d("./textures/metal_knurling_multi_heights.jpg", ::tex::gamma_linear);
	texture_2d diff_rough_grunge_tex = texture_2d("./textures/metal_knurling_multi_R_diff_G_rough_B_grunge.jpg", ::tex::gamma_linear);
	
	// Coordinate setup 
	::base::texture_coordinate_info uvw = vmat_transform(
		translation: texture_translate,
		rotation:	texture_rotate,
		scaling:	texture_scale,
		system: 	::base::texture_coordinate_uvw,
		uv_space: 	uv_space_index
	);
	
	// ---------- Diff Rough Grunge Lookup ----------
	
	float3 diff_rough_grunge_lookup = float3(
		::base::file_texture(
			texture: 	diff_rough_grunge_tex,
			uvw: 		uvw,
			mono_source: ::base::mono_average
	).tint );
	
	float3 multi_height_lookup = float3(
		::base::file_texture(
			texture: 	multi_heights_tex,
			uvw: 		uvw,
			mono_source: ::base::mono_average
	).tint );
	
	float3 norm = ::base::tangent_space_normal_texture(
		texture:	normal_tex,
		factor:		bump_strength,
		uvw:		uvw
	);
	
	
	float remap_rough = histogram_range(
		input:	diff_rough_grunge_lookup.y,
		range:	1.0f,
		position:	0.234f
	);
	
	
	float roughness_mapped = remap_rough + (roughness * multi_height_lookup.y);
	
	float remapped_diff = histogram_range(
		input:		diff_rough_grunge_lookup.x,
		range:		1.0f,
		position:	(brightness * 0.4f) + 0.4f
	);
	
	float diff_contribution = ::math::pow(remapped_diff - ((grooves_dirt * 0.5) * multi_height_lookup.x * diff_rough_grunge_lookup.z), 2.67f);
	
	bsdf ggx_smith_bumped = ::df::weighted_layer(
		layer: ::df::microfacet_ggx_smith_bsdf(
				roughness_u:	roughness_mapped * roughness_mapped,
				roughness_v:	roughness_mapped * roughness_mapped,
				tint: 			color(diff_contribution),
				mode:			::df::scatter_reflect
			),
		base: bsdf(),
		weight: 1.0f,
		normal: norm
	);
	
	bsdf diff_bsdf = ::df::diffuse_reflection_bsdf(
		tint: color(diff_contribution)
	);

	
	bsdf final_bsdf = ::df::weighted_layer(
		weight: 1.0f - (diff_rough_grunge_lookup.z * multi_height_lookup.x * grooves_dirt),
		layer:	::df::directional_factor(
			normal_tint:	metal_tint,
			grazing_tint:	color(1.0f),
			base:	ggx_smith_bumped
			),
		base: diff_bsdf
	);
	
	
	// Round Corners
	float3 round_normal = enable_round_corners ? 
		::state::rounded_corner_normal(
			radius:	roundcorner_radius * 0.001,
			across_materials: across_materials
		) : ::state::normal();
}
in material (
	
	surface: material_surface(
	scattering: final_bsdf
	),
	geometry: material_geometry(
		normal: round_normal
	)
);


export material Chromium_Knurling_Worn(*)
[[
	::anno::display_name("Metal Knurling - Chromium Worn"),
	::anno::description(DESCRIPTION),
	::anno::copyright_notice(COPYRIGHT),
	::anno::thumbnail("./.thumbs/Chromium_Knurling.Chromium_Knurling_Worn.png"),
	::anno::key_words(string[]("metal", "chromium", "knurled", "pattern", "knurling", "design", "bumped", "worn")),
	::anno::contributor("Ruediger Raab"),
	::anno::author("NVIDIA vMaterials")
]] = Chromium_Knurling(
	brightness:				0.4f,
	roughness:				1.0f,
	grooves_dirt:			1.0f,
	bump_strength:			0.8f,
	
	enable_round_corners:	false,
	roundcorner_radius:		1.2f,
	across_materials:		false,
	
	texture_translate:		float2(0.0f),
	texture_rotate:			0.f,
	texture_scale:			float2(1.0f),
	
	uv_space_index:			0
);