BSDFs#

This section contains a list of bsdfs supported by the Ignis renderer. All number and color parameters can be connected to a shading network or texture via PExpr.

A bsdf is specified in the bsdfs block with a name and a type. The type has to be one of the bsdfs listed at this section below.

{
    // ...
    "bsdfs": [
        // ...
        {"name":"NAME", "type":"TYPE", /* DEPENDS ON TYPE */},
        // ...
    ]
    // ...
}

Diffuse (diffuse)#

Parameter	Type	Default	PExpr	Description
reflectance	color	`0.8`		Albedo
roughness	number	`0`		Isotropic roughness. If roughness > 0, the Oren-Nayar model will be used.

Dielectric (dielectric)#

Parameter	Type	Default	Description
specular_reflectance	color	`1`	Reflectance factor. Should be less or equal to 1 for each component for physical correctness.
specular_transmittance	color	`1`	Transmittance factor. Should be less or equal to 1 for each component for physical correctness.
ext_ior int_ior	number	~vacuum, ~bk7	Specifies exterior and interior index of refraction.
ext_ior_material int_ior_material	string	None, None	Has to be one of the available presets listed here.
thin	boolean	false	true if the glass should be treated as a thin interface. int_ior will be always the inside of the thin surface, regardless of the direction of the surface normal.
roughness_u roughness_v	number	`0`, `0`	Roughness of the dielectric. Can be specified implicitly using roughness and anisotropic instead. thin will be ignored if roughness is greater than zero.
roughness anisotropic	number	`0`, `0`	Roughness and anisotropic terms. Can be specified explicitly using roughness_u and roughness_v instead. Anisotropic is the amount of anisotropy in the roughness distribution. thin will be ignored if roughness is greater than zero.

Conductor (conductor)#

Parameter	Type	Default	Description
eta k	color	~Perfect mirror	Real and imaginary components of the material’s index of refraction.
material	string	None	Instead of eta, k a material name can be specified. Available presets are listed here.
specular_reflectance	color	`1`	Optional factor that can be used to modulate the specular reflection component. Note that for physical realism, this parameter should never be touched.
roughness_u roughness_v	number	`0`, `0`	Roughness terms. Can be specified implicitly using roughness and anisotropic instead.
roughness anisotropic	number	`0`, `0`	Roughness and anisotropic terms. Can be specified explicitly using roughness_u and roughness_v instead. Anisotropic is the amount of anisotropy in the roughness distribution.

Plastic (plastic)#

Parameter	Type	Default	Description
specular_reflectance	color	`1`	Specular reflectance. Should be less or equal to 1 for each component for physical correctness.
diffuse_reflectance	color	`0.8`	Diffuse reflectance. Should be less or equal to 1 for each component for physical correctness.
ext_ior int_ior	number	~vacuum, ~bk7	Specifies exterior and interior index of refraction.
ext_ior_material int_ior_material	string	None, None	Has to be one of the available presets listed here.
roughness_u roughness_v	number	`0`, `0`	Roughness terms. Can be specified implicitly using roughness and anisotropic instead.
roughness anisotropic	number	`0`, `0`	Roughness and anisotropic terms. Can be specified explicitly using roughness_u and roughness_v instead. Anisotropic is the amount of anisotropy in the roughness distribution.

Phong (phong)#

Parameter	Type	Default	PExpr	Description
specular_reflectance	color	`1`		Reflectance factor. Should be less or equal to 1 for each component for physical correctness. See note below for PBR consideration.
exponent	number	`30`		Exponent of the lobe. Greater number results into a greater peak, therefore the visible peak spot will be smaller.

Note

It is not recommended to use this BSDF for new projects as it disregards some PBR principles and is only included for legacy purposes.

Principled (principled)#

Parameter	Type	Default	Description
base_color	color	`0.8`	Base color of the principled bsdf. Should be less or equal to 1 for each component for physical correctness.
metallic	number	`0`	A number between 0 and 1. A metallic value of 1 displays a full metallic (conductor), which can not transmit via refraction.
roughness_u roughness_v	number	`0.5`, `0.5`	Anisotropic microfacet roughness for specular, diffuse and sheen reflection terms. Can be specified implicitly using roughness and anisotropic instead. The roughness is computed via the GGX method.
roughness anisotropic	number	`0.5`, `0`	The microfacet roughness for specular, diffuse and sheen reflection and anisotropic terms. The roughness is computed via the GGX method. Can be specified explicitly using roughness_u and roughness_v instead. Anisotropic is the amount of anisotropy in the roughness distribution.
ior reflective_ior refractive_ior	number	~bk7	Specifies index of refraction. To distinguish between the ior used for the reflective fresnel term use reflective_ior and for the actual refraction refractive_ior. If one of the latter two is specified, ior will be ignored.
ior_material reflective_ior_material refractive_ior_material	string	None	Has to be one of the available presets listed here. See above for the reflective and refractive use case.
thin	boolean	false	true if the bsdf should be treated as a thin interface, which affects the refraction and subsurface behavior.
flatness	number	`0`	Amount of subsurface approximation. Only available if thin is true.
specular_transmission	number	`0`	Amount of specular transmission. Should be less or equal to 1 for physical correctness.
specular_tint	number	`0`	Mix factor of white and base_color for specular reflections.
diffuse_transmission	number	`0`	Amount of diffuse transmission. Should be less or equal to 1 for physical correctness. This is often named translucency in other applications.
sheen	number	`0`	Amount of soft velvet layer resulting into a soft reflection near the edges.
sheen_tint	number	`0`	Mix factor of white and base_color for sheen reflections.
clearcoat	number	`0`	Amount of white specular layer at the top.
clearcoat_gloss	number	`0`	Amount of shininess of the clearcoat layer.
clearcoat_top_only	boolean	true	true if clearcoat should only be applied to the front side of the surface only.
clearcoat_roughness	number	`0.1`	The isotropic microfacet roughness for clearcoat. Higher values result into a rougher appearance. The roughness computed via the GGX method.

Blend (blend)#

Parameter	Type	Default	PExpr	Description
first second	bsdf	None		The two bsdfs which should be blended.
weight	number	`0.5`		Amount of blend between the first and second bsdf.

Mask (mask)#

Parameter	Type	Default	Description
bsdf	bsdf	None	The bsdf which should be masked out.
weight	number	`0.5`	Amount of masking. This is only useful if the weight is spatially varying, else it behaves like opacity.
inverted	boolean	false	true if the weight should be inverted.

Cutoff (cutoff)#

Parameter	Type	Default	Description
bsdf	bsdf	None	The bsdf which should be cutoff.
weight	number	`0.5`	Weight factor for cutoff. This is only useful if the weight or cutoff is spatially varying.
cutoff	number	`0.5`	Threshold for cutoff. This is only useful if cutoff or weight is spatially varying.
inverted	boolean	false	true if the weight should be inverted. Keep in mind that cutoff is not inverted.

Transparent (transparent)#

Parameter	Type	Default	PExpr	Description
color	color	`1`		Color tint of the transparent material.

Warning

The transparent bsdf should be used carefully, as simple techniques like Next-Event Estimation still intersect the object geometry.

Passthrough (passthrough)#

Warning

The passthrough bsdf should be used carefully, as simple techniques like Next-Event Estimation still intersect the object geometry.

Normal mapping (normalmap)#

Parameter	Type	Default	Description
bsdf	bsdf	None	The bsdf the new normal will be forwarded to.
map	color	`1`	Usually a texture used for normal mapping.
strength	number	`1`	Interpolation factor between the old and new normal.

Bump mapping (bumpmap)#

Parameter	Type	Default	Description
bsdf	bsdf	None	The bsdf the new normal will be forwarded to.
map	texture	None	A grayscale texture used for texture mapping.
strength	number	`1`	Interpolation factor between the old and new normal.

Transform (transform)#

Parameter	Type	Default	Description
bsdf	bsdf	None	Bsdf the normal transformation will be forwarded to.
normal	vector	`(0,0,1)`	Normal to use instead of the callee normal (e.g., surface normal).
tangent	vector	None	Tangent to use instead of the callee tangent (e.g., surface tangent). Will be calculated from the normal parameter if not set.

Dupuy & Jakob measured materials (djmeasured)#

Parameter	Type	Default	PExpr	Description
filename	string	None		Path to a valid brdf.
tint	color	`1`		Tint.

Klems (klems)#

Parameter	Type	Default	Description
filename	string	None	Path to a valid windows xml specifying a klems bsdf.
base_color	color	`1`	Tint.
up	vector	`(0,0,1)`	Up vector

TensorTree (tensortree)#

Parameter	Type	Default	Description
filename	string	None	Path to a valid windows xml specifying a tensortree bsdf.
base_color	color	`1`	Tint.
up	vector	`(0,0,1)`	Up vector

Radiance BRTDfunc (rad_brtdfunc)#

Parameter	Type	Default	Description
reflection_specular	color	`1`	Tint of the specular reflection lobe.
transmission_specular	color	`0`	Tint of the specular transmission lobe.
direct_diffuse	color	`0`	Tint of the direct diffuse lobe. In contrary to Radiance, Ignis has no special handling of direct light connections (NEE) inside materials. The lobe is simply added to the diffuse lobes below.
reflection_front_diffuse	color	`0`	Tint of the front-side diffuse lobe.
reflection_back_diffuse	color	`0`	Tint of the back-side diffuse lobe.
transmission_diffuse	color	`0`	Tint of the diffuse transmission lobe. This emulates translucency.

Radiance Roos model (rad_roos)#

Roos model based on the paper: Roos, A., Polato, P., Van Nijnatten, P.A., Hutchins, M.G., Olive, F. and Anderson, C. (2001), Angular-dependent optical properties of low-e and solar control windows—: Simulations versus measurements

Parameter	Type	Default	Description
refl_w refl_p refl_q	number	`0`	Roos parameters for the reflection.
trns_w trns_p trns_q	number	`0`	Roos parameters for the transmission.
reflection_front_diffuse	color	`0`	Tint of the front-side diffuse lobe.
reflection_back_diffuse	color	`0`	Tint of the back-side diffuse lobe.
transmission_diffuse	color	`0`	Tint of the diffuse transmission lobe. This emulates translucency.

List of preset index of refractions#

Currently the following materials are available as presets:

vacuum
bk7
glass same as bk7
helium
hydrogen
air
water
ethanol
diamond
polypropylene

List of preset conductors#

Currently the following materials are available as presets:

aluminum
brass
copper
gold
iron
lead
mercury
platinum
silver
titanium
none ~ a perfect mirror