Skip to content

Material

This page contains classes defined in hakowan.material module.

Declarative surface and hair material channels.

Material dataclass

Bases: Channel

Material base class.

Attributes:

Name Type Description
two_sided bool

Whether to render both sides of the surface (default: False).
back_side Material | None

An independent material for the back face of each facet (default: None). When set, the front face uses this material's owning material and the back face uses back_side; this implies two-sided rendering regardless of two_sided. Only meaningful for surface marks. A nested back_side on the back material itself is ignored.
Source code in hakowan/grammar/channel/material/material.py 
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
@dataclass(kw_only=True, slots=True)
class Material(Channel):
    """Material base class.

    Attributes:
        two_sided: Whether to render both sides of the surface (default: False).
        back_side: An independent material for the back face of each facet
            (default: None). When set, the front face uses this material's
            owning material and the back face uses ``back_side``; this implies
            two-sided rendering regardless of ``two_sided``. Only meaningful for
            surface marks. A nested ``back_side`` on the back material itself is
            ignored.

    """

    two_sided: bool = False
    back_side: "Material | None" = None

Diffuse dataclass

Bases: Material

Diffuse material.

Attributes:

Name Type Description
reflectance TextureLike

Diffuse reflectance (i.e. base color) texture (default: 0.5).
Source code in hakowan/grammar/channel/material/material.py 
31
32
33
34
35
36
37
38
39
40
@dataclass(slots=True)
class Diffuse(Material):
    """Diffuse material.

    Attributes:
        reflectance: Diffuse reflectance (i.e. base color) texture (default: 0.5).

    """

    reflectance: TextureLike = 0.5

Conductor dataclass

Bases: Material

Conductor material.

Attributes:

Name Type Description
material str

Conductor material name based on Mitsuba preset.
Source code in hakowan/grammar/channel/material/material.py 
43
44
45
46
47
48
49
50
51
52
@dataclass(slots=True)
class Conductor(Material):
    """Conductor material.

    Attributes:
        material: Conductor material name based on [Mitsuba preset](https://mitsuba.readthedocs.io/en/stable/src/generated/plugins_bsdfs.html#conductor-ior-list).

    """

    material: str

RoughConductor dataclass

Bases: Conductor

Rough conductor material.

Attributes:

Name Type Description
distribution Literal['beckmann', 'ggx', 'phong']

Microfacet distribution (default: "beckmann").
alpha ScalarTextureLike

Roughness value (default: 0.1).
Source code in hakowan/grammar/channel/material/material.py 
55
56
57
58
59
60
61
62
63
64
65
66
67
@dataclass(slots=True)
class RoughConductor(Conductor):
    """Rough conductor material.

    Attributes:
        distribution (Literal["beckmann", "ggx", "phong"]): Microfacet distribution
            (default: ``"beckmann"``).
        alpha: Roughness value (default: 0.1).

    """

    distribution: Literal["beckmann", "ggx", "phong"] = "beckmann"
    alpha: ScalarTextureLike = 0.1

Plastic dataclass

Bases: Material

Plastic material.

Attributes:

Name Type Description
diffuse_reflectance TextureLike

Diffuse reflectance (i.e. base color) texture (default: 0.5).
specular_reflectance ScalarTextureLike

Specular reflectance texture (default: 1.0).
Source code in hakowan/grammar/channel/material/material.py 
70
71
72
73
74
75
76
77
78
79
80
81
@dataclass(slots=True)
class Plastic(Material):
    """Plastic material.

    Attributes:
        diffuse_reflectance: Diffuse reflectance (i.e. base color) texture (default: 0.5).
        specular_reflectance: Specular reflectance texture (default: 1.0).

    """

    diffuse_reflectance: TextureLike = 0.5
    specular_reflectance: ScalarTextureLike = 1.0

RoughPlastic dataclass

Bases: Plastic

Rough plastic material.

Attributes:

Name Type Description
distribution Literal['beckmann', 'ggx', 'phong']

Microfacet distribution (default: "beckmann").
alpha float

Roughness value (default: 0.1).
Source code in hakowan/grammar/channel/material/material.py 
84
85
86
87
88
89
90
91
92
93
94
95
96
@dataclass(slots=True)
class RoughPlastic(Plastic):
    """Rough plastic material.

    Attributes:
        distribution (Literal["beckmann", "ggx", "phong"]): Microfacet distribution
            (default: ``"beckmann"``).
        alpha: Roughness value (default: 0.1).

    """

    distribution: Literal["beckmann", "ggx", "phong"] = "beckmann"
    alpha: float = 0.1

Principled dataclass

Bases: Material

Principled material.

Attributes:

Name Type Description
color TextureLike

Base color texture (default: 0.5).
roughness ScalarTextureLike

Roughness texture (default: 0.5).
metallic ScalarTextureLike

Metallic texture (default: 0.0).
anisotropic float

Anisotropy amount (default: 0.0).
spec_trans float

Specular transmission / transparency (default: 0.0).
eta float

Interior index of refraction (default: 1.5).
spec_tint float

Specular tint towards base color (default: 0.0).
sheen float

Sheen amount (default: 0.0).
sheen_tint float

Sheen tint towards base color (default: 0.0).
flatness float

Blend between thin and volumetric subsurface scattering (default: 0.0).
Source code in hakowan/grammar/channel/material/material.py 
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
@dataclass(slots=True)
class Principled(Material):
    """Principled material.

    Attributes:
        color: Base color texture (default: 0.5).
        roughness: Roughness texture (default: 0.5).
        metallic: Metallic texture (default: 0.0).
        anisotropic: Anisotropy amount (default: 0.0).
        spec_trans: Specular transmission / transparency (default: 0.0).
        eta: Interior index of refraction (default: 1.5).
        spec_tint: Specular tint towards base color (default: 0.0).
        sheen: Sheen amount (default: 0.0).
        sheen_tint: Sheen tint towards base color (default: 0.0).
        flatness: Blend between thin and volumetric subsurface scattering (default: 0.0).

    """

    color: TextureLike = 0.5
    roughness: ScalarTextureLike = 0.5
    metallic: ScalarTextureLike = 0.0
    anisotropic: float = 0.0
    spec_trans: float = 0.0
    eta: float = 1.5
    spec_tint: float = 0.0
    sheen: float = 0.0
    sheen_tint: float = 0.0
    flatness: float = 0.0

ThinPrincipled dataclass

Bases: Principled

Thin Principled material.

Attributes:

Name Type Description
diff_trans float

Diffuse transmission amount (default: 0.0).
Source code in hakowan/grammar/channel/material/material.py 
129
130
131
132
133
134
135
136
137
138
@dataclass(slots=True)
class ThinPrincipled(Principled):
    """Thin Principled material.

    Attributes:
        diff_trans: Diffuse transmission amount (default: 0.0).

    """

    diff_trans: float = 0.0

Dielectric dataclass

Bases: Material

Dielectric material.

Attributes:

Name Type Description
int_ior str | float

Interior index of refraction (default: "bk7").
ext_ior str | float

Exterior index of refraction (default: "air").
medium Medium | None

Medium (default: None).
specular_reflectance float

Specular reflectance (default: 1.0).
specular_transmittance float

Specular transmittance (default: 1.0).
Source code in hakowan/grammar/channel/material/material.py 
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
@dataclass(slots=True)
class Dielectric(Material):
    """Dielectric material.

    Attributes:
        int_ior: Interior index of refraction (default: "bk7").
        ext_ior: Exterior index of refraction (default: "air").
        medium: Medium (default: None).
        specular_reflectance: Specular reflectance (default: 1.0).
        specular_transmittance: Specular transmittance (default: 1.0).

    """

    int_ior: str | float = "bk7"
    ext_ior: str | float = "air"
    medium: Medium | None = None
    specular_reflectance: float = 1.0
    specular_transmittance: float = 1.0

ThinDielectric dataclass

Bases: Dielectric

Thin dielectric material.

Source code in hakowan/grammar/channel/material/material.py 
161
162
163
164
165
@dataclass(slots=True)
class ThinDielectric(Dielectric):
    """Thin dielectric material."""

    pass

RoughDielectric dataclass

Bases: Dielectric

Rough dielectric material.

Attributes:

Name Type Description
distribution Literal['beckmann', 'ggx', 'phong']

Microfacet distribution (default: "beckmann").
alpha ScalarTextureLike

Roughness value (default: 0.1).
Source code in hakowan/grammar/channel/material/material.py 
168
169
170
171
172
173
174
175
176
177
178
179
180
@dataclass(slots=True)
class RoughDielectric(Dielectric):
    """Rough dielectric material.

    Attributes:
        distribution (Literal["beckmann", "ggx", "phong"]): Microfacet distribution
            (default: ``"beckmann"``).
        alpha: Roughness value (default: 0.1).

    """

    distribution: Literal["beckmann", "ggx", "phong"] = "beckmann"
    alpha: ScalarTextureLike = 0.1

Hair dataclass

Bases: Material

Hair material.

Color is controlled either physically, via the two melanin pigment concentrations (natural hair palette: black → brown → red → blonde), or directly via color with an RGB / named color for uniform fur of any hue. color overrides the melanin parametrization when set.

For richer fur, colors can be mixed procedurally along and across strands: root_color / tip_color give a root-to-tip gradient (dark undercoat → lighter tips), and color_variation adds per-strand random brightness jitter. These are evaluated in the hair shader (Blender), so they compose with the guide/child hairs for free.

Note: a data-driven color (e.g. ScalarField) is not supported by the hair renderers and falls back to melanin with a warning — the hair BSDF darkens/tints colors, which is poor for reading data anyway. To color fur by an attribute, use a non-Hair material (e.g. Diffuse) on the fur strands.

Attributes:

Name Type Description
eumelanin float

Eumelanin (dark/brown pigment) concentration (default: 1.3). Ignored when color or a root/tip gradient is set.
pheomelanin float

Pheomelanin (reddish-yellow pigment) concentration (default: 0.2). Ignored when color or a gradient is set.
color TextureLike | None

Direct RGB / named hair color (overrides melanin). None (default) uses the melanin parametrization.
root_color ColorLike | None

Strand-root color of a root-to-tip gradient. Setting root_color and/or tip_color overrides color and melanin.
tip_color ColorLike | None

Strand-tip color of the root-to-tip gradient.
color_variation float

Per-strand random brightness jitter in [0, 1] (0 = uniform). Applied on top of the melanin / color / gradient.
Source code in hakowan/grammar/channel/material/material.py 
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
@dataclass(slots=True)
class Hair(Material):
    """Hair material.

    Color is controlled either physically, via the two melanin pigment
    concentrations (natural hair palette: black → brown → red → blonde), or
    directly via ``color`` with an RGB / named color for uniform fur of any
    hue.  ``color`` overrides the melanin parametrization when set.

    For richer fur, colors can be mixed procedurally along and across strands:
    ``root_color`` / ``tip_color`` give a root-to-tip gradient (dark undercoat →
    lighter tips), and ``color_variation`` adds per-strand random brightness
    jitter.  These are evaluated in the hair shader (Blender), so they compose
    with the guide/child hairs for free.

    Note: a *data-driven* color (e.g. ``ScalarField``) is not supported by the
    hair renderers and falls back to melanin with a warning — the hair BSDF
    darkens/tints colors, which is poor for reading data anyway.  To color fur
    by an attribute, use a non-Hair material (e.g. ``Diffuse``) on the fur
    strands.

    Attributes:
        eumelanin: Eumelanin (dark/brown pigment) concentration (default: 1.3).
            Ignored when ``color`` or a root/tip gradient is set.
        pheomelanin: Pheomelanin (reddish-yellow pigment) concentration
            (default: 0.2).  Ignored when ``color`` or a gradient is set.
        color: Direct RGB / named hair color (overrides melanin).  ``None``
            (default) uses the melanin parametrization.
        root_color: Strand-root color of a root-to-tip gradient.  Setting
            ``root_color`` and/or ``tip_color`` overrides ``color`` and melanin.
        tip_color: Strand-tip color of the root-to-tip gradient.
        color_variation: Per-strand random brightness jitter in ``[0, 1]``
            (0 = uniform).  Applied on top of the melanin / color / gradient.

    """

    eumelanin: float = 1.3
    pheomelanin: float = 0.2
    color: TextureLike | None = None
    root_color: ColorLike | None = None
    tip_color: ColorLike | None = None
    color_variation: float = 0.0

    def __post_init__(self) -> None:
        if self.eumelanin < 0.0 or self.pheomelanin < 0.0:
            raise ValueError("Hair melanin concentrations must be non-negative.")
        if not 0.0 <= self.color_variation <= 1.0:
            raise ValueError("Hair.color_variation must be in [0, 1].")