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Cel Edges

In the early days of animation, all art was hand drawn on transparent acetate called a Cel and painted with flat solid colors. This produced a unique look that is still highly desirable even today. The Cel Edges material attempts to mimic the hand drawn look of the outlines of these cartoons, creating colored strokes that follow surface contours and edges.

Constant Color

When combined with a Cel Material item, a low-fidelity cartoon-like look can be achieved. You can add the material to any surface using the Add Layer function of the Shader Tree, found in the menu under Custom Materials > Cel Edges Material.

NOTE:  For information regarding adding and working with Shader Tree Items Layers, please see Shader Tree.

Constant Panel





Toggles the effect of the layer on and off, duplicating the functionality of toggling visibility in the Shader Tree. When disabled, the layer has no effect on the shading of the scene. However, disabled layers are saved with the scene and are persistent across Modo sessions.


Inverts the RGB values for the layer producing a negative effect.

Blend Mode

Affects blending between different layers of the same effect type, allowing you to stack several layers for different effects. For more on blending, please see Layer Blend Modes.


Changes the transparency of the current layer. Reducing this value increasingly reveals lower layers in the Shader Tree if present, or dims the effect of the layer itself on the surface.


Most texture layers also have an associated Texture Locator that is automatically created in the Item List. This defines the mapping of the texture (the way the texture is applied) to the surface. The Locator option sets that association. You can choose alternate locators, however, the need to do so is very rare. There are, however, some instances where you may want multiple texture items to share a single locator.

Cel Edge Material

Edge Width

Defined as a pixel value, this control determines the overall width of the edge stroke.

TIP:  You should adjust this value when changing frame resolution because a two pixel contour appears half as thick when the render resolution is doubled.

Edge Color

This value determines the color of the actual stroke.

Incidence Edges

This value determines the amount that the Incidence Edges contribute to the final Cel edge. Incidence edges are those that appear at the steepest glancing angles, perpendicular to the camera. This is useful for obtaining a more organic thick and thin stroke, as the incidence angle changes depending on the surfaces position relative to the camera.

Angle Edges

This value determines the amount that interior contour edges, within the Min and Max Angle values, contribute to the final Cel Edge.

Min/Max Angle

These two values determine the angle spread between opposing polygonal surfaces where a stroke is rendered. Typically, only an adjustment to the Max value is necessary. Lowering the value produces more contour edges and raising it produces progressively less.

Distance Edges

This function detects which interior areas of a surface are considered edges when surface contours overlap. Edges are shaded when two adjacent sampling points are greater than the given threshold.


This value is used to determine the distance between adjacent sampling points for Distance Edges. Increasing it produces fewer interior edges for a surface, while decreasing it produces more edges.

Edge Quality

This value determines the overall quality of the Cel edges. Increasing this value produces cleaner edges, as more edge determining rays are fired, at the expense of longer render times.