Features Implemented

1. Inspiration

Artist: Katawoka

Ghost Girl Illustration

My inspiration for my stylized shader was this comic style illustration to the left. There were a few visual elements from this piece I wanted to incorporate into my toon shader:

• Half tone shading
• Outlined shadows
• Minimal color palette

Credit: Robot Model by Tasha Lime

Robot Scene Assets

• Because the main focus of this project was to create an interesting stylized shader, I chose to import my main asset from SketchFab.
• I chose this sad looking robot character because I thought it replicated the melancholy expression of the girl in the illustration.
• The other assets in the scene are simple cubes and spheres made in Unity.

2. Interesting Shaders

• This was achieved by using three threshold values to bucket the colors in the scene. These values control the amount of Highlight, Midtone, and Shadow seen on the meshes and can be customized by the user.

• The specular highlight appears on objects in the scene as a white dot at bright spots of light.
• This was created by using the view vector from the current fragment to the camera and the reflected light vector. The reflected light vector can be calculated using the normal vector and the vector from the current vertex to the light position.
• The angle between the reflection vector and the view vector can be found with a dot product. This angle is then used to determine the amount of specular reflection the current fragment gets.
• This is added to the diffuse color value and creates the bright spot of white!

• I thought the outlines on the shadows of my inspiration piece were really interesting! I achieved a similar look in my scene, exemplified well in the image below.

• We can see the outline on the shadows on both the ground and the robot.
• The shadow outline on the robot separates the light teal color from the darker green color on the front of the robot and follows the shape of the boundary between the Highlight and the Shadow tones
• Shadow Outline color and width can be customized by the user

• This was a simple effect done by using the logic of the Three Tone Shader but decreasing the size of the Midtone so it acted as an outline instead of a tone. (The reason the robot still looks like it has multiple tones — more than a 2 tone shader — is because of the point lights creating a bucketed coloring effect!)

To implement half tones, I first created a custom half tone texture.

• I used a brush tool in Procreate to draw the dots to make it look hand-drawn.

I also used the above node network to implement the half tones:

• I sampled the UVs of the half tone texture, making sure to first tile + offset and rotate the UV to make it more visually interesting.
• To be able to customize the color of the dots on the shadow, I take the minimum of the Shadow color and the sampled texture color. Thus, if we are sampling one of the dots, then the minimum will be black (the dot color) and the color of the Shadow otherwise.
• We then ensure the color of the dots is colored correctly with the Shadow Dots color (rather than fixing the color of the dots to be black from the sample texture). We do this by taking the maximum of the sampled color and the Shadow Dots color, which will return Shadow Dots if we originally sampled a dot or Shadow if we originally sampled empty space around the dots.
• The user can customize Shadow, Shadow Dots, and Shadow Tiling, which control the color of the shadow, the color of the dots, and the size of the dots.

Screenshot of back view to demonstrate half-tone shading

To implement half tones, I first created a custom half tone texture.

• I used a brush tool in Procreate to draw the dots to make it look hand-drawn.

I also used the above node network to implement the half tones:

• The intersection of the lights can be seen in the scene below. I increased the intensity of the second light here and made it purple to exaggerate the visual effect.
• We can see the interaction of the two lights at areas where they overlap — note the brighter spots
• The lights also change the appearance of the shadows and help overall bring more complexity to the scene

Example scene to illustrate additional lights

• I created a second shader based on above, with some added vertex deformation.
• For each vertex, I interpolate between its original position and an animated offset position.
• The animated position is created by offsetting the x position of the vertex using a sine curve, with time and several exposed parameters (like speed and frequency) as an input. This creates a nice wiggly-wobbly effect!
• The user can tweak the Wobble Speed, Wobble Frequency, Wobble Distance, and Wobble Amount, to customize the intensity of the wobbly animation.

I also used the above node network to implement the half tones:

• The intersection of the lights can be seen in the scene below. I increased the intensity of the second light here and made it purple to exaggerate the visual effect.
• We can see the interaction of the two lights at areas where they overlap — note the brighter spots
• The lights also change the appearance of the shadows and help overall bring more complexity to the scene

3. Outlines

Left: Example scene with Depth-based outlines; Right: Example wobble effect on outlines

I. DEPTH-BASED OUTLINES

In order to create depth based outlines, I used Unity’s URP to get access to the Depth buffer. Then, I used a Sobel outline implementation to detect large differences in depth.

• There are several adjustable parameters, including outline Width, ColorThreshold (adjusts amount of outlines), and Strength (adjusts the strength/opacity of the outlines)
• To make the outlines more interesting, I decided to add a wobble effect using similar logic for the wobble shader.
• The intensity of wobble can also be adjusted by the user, similar to the shader wobble effect described above.

II. NORMAL-BASED (COLOR) OUTLINES

Because my inspiration piece included outlines between different tones, I also chose to implement normal based outlines which achieved the outlines between colors.

• I used a Normal Shader feature and added a material made from it to the render pipeline. I then connected a Normal Buffer texture as the destination target for this render feature.
• Using this Normal Buffer texture, I was able to detect large difference in normals across the screen, which I used to create color-based outlines.
• These outlines had the same adjustable parameters as the Depth-based ones.

4. Cohesive Color Saturation Filter

• To adjust saturation, I interpolated between the original color and and a grayscale color defined based on the original input color. The user can tweak the amount of saturation by adjusting the xyz components of the Sat parameter (which is the input for interpolation).
• To tweak the color palette, the user can individually change each of the xyz components of the Sat parameter. Because they correspond to the amount of rgb mixing, doing so will vary the colors shown in the final output.
• Below are some the results that can be achieve with this post-processing effect:

Scene with no color saturation post-processing effect applied

Scene with color saturation post-processing effect applied

5. Interactivity

Scene with colors from Green/Orange color palette attached

Scene with colors from Gray/Purple color palette attached

6. Extra Polish

• Pixelization — achieved by bucketing the UV sampling of the scene’s main color texture
• Dots Overlay — overlays a grid of dots on top of the main texture to mimic a TV screen. This was done by using the output of a Voronoi texture to sample a three tone color gradient. Decreasing the opacity of the gradient and then subtracting it from the main color achieved the dotted texture.
• Static Distortion Effect — creates the glitchy warping effect that can be seen best along the edges of the objects in the scene
• Color Distortion — distorts the colors of the scene to achieve different kinds of retro color styles