Custom shader fundamentals in Unity - Mini Project: Build & Apply

Custom shader fundamentals

📖 Scenario: You are creating a simple visual effect in a Unity game. You want to write a custom shader that colors an object with a solid color.

🎯 Goal: Build a basic Unity shader that colors an object with a fixed color using shader code.

📋 What You'll Learn

Create a shader with a fixed color property

Write the shader code to output the fixed color

Apply the shader to an object in Unity

Print the final color output in the shader

💡 Why This Matters

🌍 Real World

Custom shaders let game developers create unique visual styles and effects for objects in games and apps.

💼 Career

Understanding shader fundamentals is important for graphics programmers, technical artists, and game developers working with Unity.

1

Create a shader with a fixed color property

Create a shader named SimpleColorShader with a _Color property set to (1, 0, 0, 1) (red). Write the shader declaration and properties block.

Unity

// Write the shader declaration and properties block
// Your code here

Need a hint?

Start by declaring the shader name and add a Properties block with a color named _Color set to red.

2

Add a fixed color fragment shader

Inside the SubShader, add a Pass with a fragment shader named frag that returns the _Color value. Also add a vertex shader named vert that passes vertex data unchanged.

Unity

Shader "Custom/SimpleColorShader" {
    Properties {
        _Color ("Color", Color) = (1, 0, 0, 1)
    }
    SubShader {
        // Add a Pass with vert and frag shaders here
        // Your code here
    }
}

Need a hint?

Inside SubShader, add a Pass with CGPROGRAM. Define vert and frag functions. The fragment shader should return the _Color.

3

Add a helper variable for color intensity

Add a float property named _Intensity with default value 1.0 in the Properties block. Then declare float _Intensity; inside the shader code and multiply _Color by _Intensity in the fragment shader before returning.

Unity

Shader "Custom/SimpleColorShader" {
    Properties {
        _Color ("Color", Color) = (1, 0, 0, 1)
        // Add _Intensity property here
        // Your code here
    }
    SubShader {
        Pass {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            // Declare _Intensity variable here
            // Your code here

            fixed4 _Color;

            v2f vert(appdata v) {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target {
                // Multiply _Color by _Intensity here
                // Your code here
            }
            ENDCG
        }
    }
}

Need a hint?

Add a float property _Intensity in Properties. Declare it in the shader code and multiply it with _Color in the fragment shader.

4

Print the final color output

Add a Debug.Log statement in the fragment shader to print the final color value before returning it. Then print the final color output in Unity console.

Unity

Shader "Custom/SimpleColorShader" {
    Properties {
        _Color ("Color", Color) = (1, 0, 0, 1)
        _Intensity ("Intensity", Float) = 1.0
    }
    SubShader {
        Pass {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            float _Intensity;

            struct appdata {
                float4 vertex : POSITION;
            };

            struct v2f {
                float4 pos : SV_POSITION;
            };

            fixed4 _Color;

            v2f vert(appdata v) {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target {
                // Add Debug.Log to print final color
                // Your code here
                return _Color * _Intensity;
            }
            ENDCG
        }
    }
}

Need a hint?

Shaders cannot use Debug.Log directly. Instead, return the final color multiplied by intensity. When applied to an object, the color should appear red with full intensity.