How can I implement edge detection to outline objects in Unity’s art style?

Implementing Edge Detection to Outline Objects in Unity

Using Shader Graph for Edge Detection

Unity’s Shader Graph offers a flexible and powerful way to implement edge detection to outline objects. Below are steps to create an outline shader using Shader Graph:

1. Create a new Shader Graph by right-clicking in the Project window and selecting Create > Shader > PBR Graph.
2. Open the Shader Graph and add the nodes that will serve as inputs for edge detection. These include the Normal Vector and the Screen Position.
3. Use a Dot Product node to calculate the angle between the surface normal and the view direction.
4. Incorporate an Edge Detection algorithm using Fresnel Effect by connecting a 1- node to the dot product result.
5. Define the outline color and thickness with corresponding Color and Float nodes, and use a Multiply node to manipulate the thickness of the effect.
6. Connect the output to the Fragment output node. Save the graph and apply this shader to a material.

Programming Edge Outlines with C#

In cases where more control is needed or when Shader Graph is restricted, C# scripting can be employed to dynamically outline objects:

Play, have fun, and win!

using UnityEngine;
public class EdgeDetectionOutline : MonoBehaviour {
    public Material OutlineMaterial;
    void OnRenderObject() {
        OutlineMaterial.SetPass(0);
        GL.Begin(GL.LINES);
        // Insert edge detection logic here
        GL.End();
    }
}

Implementing edge detection through script involves using GLSL or even HLSL to handle vertex and fragment operations. You might leverage existing libraries or engines like OpenGL as hinted in resources like ‘https://stackoverflow.com/questions/how-to-draw-edges-between-vertices-in-opengl‘ to handle complex drawing tasks.

Best Practices for Performance

• Use Graphics.DrawMeshInstanced instead of Graphics.DrawMesh to minimize draw calls when handling multiple objects.
• Balance performance and visual quality by adjusting the outline thickness in low-performance scenarios.
• Consider combining edge detection with object culling techniques for large scenes to reduce processing overhead.