by Benjamin Mikhaiel, model by Martin Trafas	Models from polyhaven.com	Robot model by Ian Robinson

Toon Shader Non-Photorealistic Rendering	Standard Material Physically Based Rendering

Color remapping a noise texture

Tone mapping a Toon shader with an Area Light

Tone mapping a Toon Shader with an Infinite Light

Tonemap: Stepped Color Ramp Base Color: White	Stepped Grayscale Ramp Color texture map

Light Type: Infinite Light Changing Shadow Softness	Area Light Changing Area Light Size

Changing light intensity	Changing a light's shadow transparency

Changing ramp exposure

Controls the main color of the Toon shader. This the most common place to connect a primary color texture. The Base Color is multiplied with the Base Tonemap color, setting the Base Color to white allows the full Base Tonemap color to come through while setting it to black results in no color.

 

Controls the brightness of the base color from 0 to 1.

 

Controls the shading with an externally connected ramp or texture node. This is where you give a Toon shader a cel shaded look and is one of the most important inputs to adjust. Using a ramp with stepped interpolation results in a classic cel shaded look where the transition between highlight and shadow is abrupt and sharp. You can use ramps with any type of interpolation, stepped and smooth transitions can even be used in the same ramp, however, mixed interpolation types will not look as sharp as a ramp that only uses stepped interpolation. The Base Tonemap color is multiplied with the Base Color.

By default, with no connected ramp node, the Base Tonemap results in a linear black to white shaded style as seen in the example on the right below.

 

Tone mapping works by mapping the light intensity on the objects in your scene (the illuminance) to a ramp node with colors and shading defined by you. With a horizontal ramp, the left side of the ramp controls the shadow color, the middle part of the ramp controls the midtone colors, and the right part of the ramp controls the highlight color. Light intensity has a direct impact on how much of your tonemap is used, for example, if you don't see the highlight portion of a ramp on your objects then you either need to make the lighting brighter or change the position of the highlight color in your ramp.

In the examples below the ramp used in each can be seen at the bottom of the image. Take note of how the ramp is mapped to the scene, with the darkest parts of the scene mapping to the left side of the ramp and the brightest parts mapping to the right side of the ramp. Understanding the relationship between scene lighting and a tonemap is important to achieving any kind of stylized look you can come up with.

 

When bump mapping is used it distorts the tone mapping which allows for stylized shading. In the examples below, note how the shading appears less uniform.

 

The Base Tonemap Modes controls how Base Tonemap shading behaves in shadow, this includes shadows from other objects and self shadows.

By default, the Light and Opaque Shadow mode does not change how tone mapping is applied when in shadow. In this mode, a shadow is able to dim or even change the color of the tone mapping underneath (if is casting a colorful shadow) but all tone mapping transitions stay in the same place whether they are in or out of shadow. Lower opacity shadows make the underlying region brighter while more opaque shadows make it darker.

By comparison, the Light and Shadow mode actually changes how tone mapping is applied in shadows and adheres strictly to the colors used in the tonemap. In this mode, a shadow is able to shift the tone mapping underneath along the tonemap ramp — how far, and in which direction, this shift travels depends on the opacity of the shadow. Lower opacity shadows shift the tone mapping into the brighter part of a ramp, while more opaque shadows shift the tone mapping further into the shadow part of the ramp.

In the examples below, two fully opaque bars cast a shadow on the objects below and the Toon shader's Base Shadow Opacity is adjusted to demonstrate the effect shadow transparency has on each mode, this setting can be found in the Toon shader's Advanced section. When using the Light and Shadow mode, the tonemap ramp can be seen creeping along the surface of the object as shadow opacity decreases from the default value of 0. However, when using the Light and Opaque Shadow mode the tonemap does not move. Keep in mind that shadow transparency can also be adjusted on lights.

Controls where specular reflections (direct reflections from light sources) are able to be seen with an externally connected ramp. A ramp used with the Tonemap Layer Mask is mapped in exactly the same way as the Reflection Tonemap, the darkest part of a specular reflection maps to the left side of a horizontal ramp while the brightest part maps to the right side — light intensity and light angle directly affect where this is applied on your objects and move in unison with the Reflection Tonemap. Bright colors increase the opacity of the specular reflection while dark colors decrease the opacity — the same general functionality as any layer mask where black removes from the layer being masked. By default, with no input ramp, the specular reflection can be visible everywhere.

Since the Tonemap Layer Mask is mapped onto the object based on light angle and intensity it cannot be used to mask out specular reflections in certain parts of an object. Instead, this should be controlled with a texture in the overall Reflection Color below, using black areas to stop the specular reflection from being visible or just dimming them with darker colors.

In the examples below you can see how the ramp controls where the specular reflection is visible and how brightness and color affect how intense that reflection is. In most situations you want bright colors in the ramp on the right side so the brightest part of a specular reflection is more intense than the darkest — usually with black on the left side of the ramp so that the specular reflection isn't visible across the entire object. However, since the layer mask is extremely flexible, if you actually want to mask out the brightest part of a highlight that is possible by making the right side of the ramp black as seen in the animated example. In the Smooth Rainbow example, note how the objects are tinted by color everywhere — even in shadow — because there is no black in the ramp so the specular reflections. In the other examples, the left side of the ramp is black so that the darkest parts are not tinted.

 

Controls the main reflection color of the Toon shader. This the most common place to connect a reflection color map. The Reflection Color is multiplied with the Reflection Tonemap and masked away by a Tonemap Layer Mask if present. Setting Reflection Color to white allows the full Reflection Tonemap to come through while setting it to black results in no color.

 

Controls the overall brightness of reflections.

 

Controls the size of specular reflection highlights. Higher roughness values result in larger specular highlights while lower values result in smaller highlights, using a roughness texture map will create a variable size and shape.

 

Controls whether the fresnel effect has an impact on reflection intensity. When enabled, by default, the intensity of reflections varies heavily based on light angle and reflection roughness — this realistically emulates how reflections behave in physically based rendering. However, for more stylized reflections, disabling fresnel might produce a more desirable result that is easier to control.

For example, when fresnel is enabled, high roughness values can cause reflections to quickly lose intensity. With the Toon shader, when a reflection loses intensity the specular highlight also gets smaller, this can be counter-intuitive if you want a wide specular highlight. In the examples below, take note of how the specular highlight stays much smaller, and even disappears, as Reflection Roughness changes with Fresnel enabled.

 

Short for Index of Refraction, controls how light rays traverse a medium and bend when changing mediums. In a practical sense, changing the IOR adjusts how intense reflections become when Fresnel is enabled. A value of 1 is equivalent to how light behaves in a vacuum, resulting in no bending of the light as a vacuum does not interact with the light rays at all. In the real world, normal materials never have an IOR below 1 because that would be impossible, as it would mean light travels faster in this medium than it does in a vacuum.

 

Controls how many samples are used for reflections, this mainly effects rough indirect reflections. Higher values reduce reflection noise but take longer to render, while lower values increase the chance for reflection noise but render faster.

 

Controls the look of specular highlights with an externally connected ramp or texture node. Reflection Tone mapping works by taking the specular intensity of the lighting in your scene and mapping that to a ramp node with colors and shading defined by you. With a horizontal ramp, the left side of the ramp controls the dimmest part of a highlight, the middle part of the ramp controls the midtone colors, and the right part of the ramp controls the brightest part of a highlight. Light intensity has a direct impact on how much of your tonemap is used and how large the specular highlights appear, for example, if your specular highlights are too small then you might make the lighting brighter, change the reflection roughness, or change the position of the highlight color in your ramp.

The Reflection Tonemap color is multiplied with the Reflection Color and masked away by the Reflection Tonemap Layer Mask. By default, with no connected ramp node , the Reflection Tonemap results in a linear black to white shaded style as seen in the right example below.

 

In the examples below, note how the specular intensity of the light in the scene corresponds to the different parts of the ramps that can be seen at the bottom of each image. The dark parts of the specular reflections map to the left side of the ramp and the bright parts map to the right side of the ramp.

 

When bump mapping is used it distorts the tone mapping.

 

The Reflection Tonemap Modes control how specular reflections behave in shadow, this includes self shadows and shadows from other objects.

By default, the Light and Opaque Shadow mode does not change how tone mapping is applied when in shadow. In this mode, a shadow is able to dim or even change the color of the tone mapping underneath (if is casting a colorful shadow) but all tone mapping transitions stay in the same place whether they are in or out of shadow. Lower opacity shadows make the underlying specular highlight brighter while more opaque shadows make it darker.

By comparison, the Light and Shadow mode actually changes how tone mapping is applied in shadows and adheres strictly to the colors used in the tonemap. In this mode, a shadow is able to shift the tone mapping underneath along the tonemap ramp — how far, and in which direction, this shift travels depends on the opacity of the shadow. Lower opacity shadows shift the tone mapping of the specular highlight into the brighter part of a ramp and make it larger. While more opaque shadows shift the tone mapping of the specular highlight further into the shadow part of the ramp and make it smaller.

 

In the examples below, two fully opaque bars cast shadows on the objects below and the Toon shader's Reflection Shadow Opacity is adjusted to demonstrate the effect shadow transparency has on each mode, this setting can be found in the Toon shader's Advanced section. When Light and Shadow mode is used, note how the specular reflection shifts along the tonemap ramp and gets smaller when the shadows get darker and more opaque. However, when using Light and Opaque shadow, the specular highlights stay the same size and only the overall brightness changes.

 

In the next example, a large transmissive plane casts a colorful stained glass window effect on the objects below. When using Light and Opaque Shadow the specular reflections are tinted by the stained glass effect, taking on their color and dimming as the shadows become more opaque. However, when Light and Shadow mode is used, the specular highlights shift and shrink at different rates depending on where the different parts of the stained glass effect land. For both modes, when Reflection Shadow Opacity is at +1, there is no visible specular reflection because the transmissive object is casting a completely opaque shadow.

 

When the Stylized mode is used, a texture connected to the Reflection Tonemap input is used to create a stylized specular highlight based on the position and intensity of selected lights.

Stylized
Tonemap Mode

 

Here, up to four lights can be added to the Light List to drive the placement and intensity of stylized reflection highlights, any excluded lights are ignored for this effect.

Controls the color of the rim lighting effect. Rim lighting does not cast shadows but it is dependent on the position of the lights selected to participate in the effect.

Rim Color is multiplied with the Rim Tonemap color.

 

Controls the overall brightness of the rim lighting.

Light intensity influences the intensity of the rim lighting effect, if you don't see any rim lighting your selected lights might not be bright enough.

 

Controls the thickness of the rim lighting. This is similar to controlling the falloff of a fresnel shader.

 

Controls how focused the rim lighting is, low values shrink the spread of the rim effect around the incoming direction of rim lights. A value of 0 disables the rim lighting.

There are two rim lights in the example below, notice how at low values the rim effect is narrow and localized around the incoming light angle. By comparison, when this value is high the rim effect is spread out along the silhouette of an object and the effect from each light even overlaps .

 

Controls how the rim light fades out to the terminator edge. Low values result in an abrupt transition while high values fade out gradually.

 

The Rim Tonemap can be used to map a ramp along the width of the rim effect.

Rim Tonemap is not based on scene lighting the way Base Tonemap and Reflection Tonemap work.

 

Here, up to four lights can be added to the Light list to drive the angle of the rim lighting, any excluded lights are ignored for this effect.

If no lights are added, Rim lighting is equivalent to a uniform fresnel effect.

 

Controls the color of emitted light.

For NPR styles, emission can be useful in ways that it isn't with traditional PBR workflows. Since cel shaded looks tend to have a flat look already, emission can be used as another way to add interesting flat looks to your shader.

 

Controls the intensity of the emitted light.

 

By default the Toon shader does not receive global illumination, because Base Indirect Scale is set to 0, so it is important to be careful with emission as it will cast indirect illumination on objects that can receive GI.

 

Controls the overall transparency of the material. Brighter colors are more opaque while darker colors are more transparent. White, by default, results in a fully opaque object.

 

When enabled, any emissive effects are affected by opacity. For example, if you have a bright orange emissive texture but opacity is set to a low value, you will only get a dim orange result.

When disabled, emissive effects are not affected by opacity. In this mode, it is easier to separately control emission and opacity and bright emissive areas that stack on top of each other will be rendered additively. Disabling Opacity Affects Emission is a great way to render additive particle effects.

 

When enabled, reflections are affected by opacity masking just like any other part of the material.

When disabled, reflections are not affected by opacity masking, instead reflections will remain untouched which can create the illusion of a transparent toon material.

In the example below a window is placed in the scene and the pane of glass has a toon shader applied with a completely black opacity. When Opacity Affects Reflection is enabled you can see entirely through the glass but there is no indication of any reflective surface. When it is disabled, you can still see through the glass but the toon reflection comes back and the opacity of the stylized reflection can be controlled with the reflection weight.

 

When enabled, the rim light effect is affected by opacity masking just like any other part of the material.

When disabled, the rim light effect is not affected by opacity masking, instead rim shading will remain untouched which can create the illusion of a transparent toon material.

 

Connect a bump map node and texture here. Bump mapping affects all aspects of the Toon shading, including breaking up the transitions between cel shading in a tonemap ramp. Low bump intensities can go a very long way with toon shading.

 

This enables the per-material Trace Depth parameters below. When disabled, global trace depths from the render settings are used.

 

This parameter controls the trace depth for reflection rays shot from this material. If the reflection rays of a material are not very defined (meaning they are blurry because of high roughness or have a low reflection weight), then multiple bounces can be a waste of rendering time. This parameter allows the user to reduce the trace depth and speed up rendering on a per-material basis.

 

This parameter allows you to override the global cut-off setting for reflections.

 

When the reflections of a material are very dark (because of low "Weight" or "Color" values) they contribute very little to the final image. This parameter defines what is considered "very dark" at which point no more reflection rays will be shot — which will speed up rendering. Scenes containing very strong lights might need this parameter set to very low values such as 0.0001 in order to avoid early termination which can produce a grain-like effect.

 

Controls the weight of indirect illumination base rays, i.e. the effect of global illumination on the base shading of the Toon shader. By default, the Toon shader has indirect illumination disabled with a Base Indirect Scale of 0. This is frequently desirable so that toon shading remains flat, however, the Base Indirect Scale can be increased to enable the effects of global illumination.

 

Controls the weight of indirect reflection rays, i.e. reflections of other surfaces (including self reflections) — this does not include specular reflections, i.e. reflections of light objects. By default, the Toon shader has indirect reflection disabled with a Reflection Indirect Scale of 0. This is frequently desirable so that toon shading remains flat and looks less like a traditional PBR style, however, the Reflection Indirect Scale can be increased to enable this here.

 

Controls the transparency level of shadows cast on the Base layer of the Toon shader, including self shadows.

In the examples below, two fully opaque bars cast a shadow on the objects below and the Toon shader's Base Shadow Opacity is adjusted to demonstrate the effect shadow transparency has on each Tonemap Mode. On the right side is what each Tonemap mode looks like at the default value — in a scenario with opaque shadows, note that both Tonemap modes look identical and only look different when the shadows become transparent. For more detailed information on the behavior of each mode, please see the Base Tonemap Mode section of the Toon shader.

 

In the next example, a large transmissive plane casts a colorful stained glass window effect on the objects below. On the right side is what each Tonemap mode looks like at the default value — in a scenario with shadows cast from a transmissive object, note that the two modes look different from each other. The Light and Opaque Shadow mode takes on the color of the stained glass while the Light and Shadow mode does not.

 

Controls the transparency level of shadows cast on the Specular Reflection layer of the Toon shader, including self shadows.

In the examples below, two fully opaque bars cast a shadow on the objects below and the Toon shader's Reflection Shadow Opacity is adjusted to demonstrate the effect shadow transparency has on each Tonemap Mode. On the right side is what each Tonemap mode looks like at the default value — in a scenario with opaque shadows, note that both Tonemap modes look identical and only look different when the shadows become transparent. For more detailed information on the behavior of each mode, please see the Base Tonemap Mode section of the Toon shader.

 

In the next example, a large transmissive plane casts a colorful stained glass window effect on the objects below. On the right side is what each Tonemap mode looks like at the default value — in a scenario with shadows cast from a transmissive object, note that the two modes look different from each other. The Light and Opaque Shadow mode takes on the color of the stained glass while the Light and Shadow mode does not.

 

This setting controls what is reflected when the Reflection Trace Depth is exceeded.

• Base: The final reflection color is taken from the base color of the toon shader.
• Environment: The final reflection is taken from an available environment shader (like a dome light) or will be black if there is no environment.

When trace depths are low or an object's shape creates many self reflections and this parameter can have an enormous difference on the final look. Increasing the reflection trace depths will fix this issue, resulting in more realistic dark reflections, but this comes at the expense of render times. Sometimes setting Reflection End Color to "Base" is enough to produce a very similar darkened result to increasing the trace depths but avoids increased render times.

 

Controls how the reflection layer observes energy compensation from the following options:

• Use Fresnel: Layering is weighted by the albedo weight multiplied by fresnel. This matches other uber shaders like the Standard Material.
• No Fresnel: Reflection layer weight is based on the Reflection Weight. This can result in the reflection layer completely overpowering the rest of the shader at the default Reflection Weight of 1.
• None: No energy compensation is used, the base and reflection layers are added together.

 

Controls if a an object is visible in itself through areas of semi-transparency. A semi-transparency area is anywhere a grey value appears in an opacity map. Opacity maps without semi-transparency, purely black and white maps, are unaffected by this option.

In the example below a tile shader is used for the opacity map with the grout and bevel width animated in order to demonstrate the effect. When the tile shader, pictured below on the right, has smooth transitions between white and black semi-transparency is involved and the effect can be seen. If disabled, instead of revealing the backside of the object through the semi-transparent sections it is completely skipped showing only the white background behind them.

However, when this parameter is enabled — or when the tile shader is only black and white with harsh edges — the opacity behaves as normal.