Unlit vs lit shaders in Unity - Visual Side-by-Side Comparison

Concept Flow - Unlit vs lit shaders

Start: Object Render

↓

Choose Shader Type

↓

Unlit Shader

↓

No Lighting

↓

Apply Color

↓

Display Object on Screen

When rendering an object, the system chooses between unlit or lit shaders. Unlit shaders skip lighting calculations and show color directly. Lit shaders calculate lighting before showing the final color.

Execution Sample

Unity

Shader "Custom/UnlitColor" {
  SubShader {
    Pass {
      Lighting Off
      Material {
        Diffuse (1,0,0,1)
      }
    }
  }
}

// Lit shader calculates lighting before color

This example shows a simple unlit shader that colors an object red without lighting effects.

Execution Table

Step	Shader Type	Lighting Calculation	Color Applied	Output
1	Unlit	Skipped	Red (1,0,0,1)	Object appears solid red, no shading
2	Lit	Calculated based on lights and normals	Red modulated by light	Object appears red with shading and highlights
3	Unlit	Skipped	Blue (0,0,1,1)	Object appears solid blue, flat color
4	Lit	Calculated	Blue modulated by light	Object appears blue with shading
5	End	-	-	Rendering complete

💡 Rendering ends after applying shader color with or without lighting

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
Shader Type	None	Unlit	Lit	Unlit	Lit	None
Lighting Calculation	None	Skipped	Calculated	Skipped	Calculated	None
Color Applied	None	Red	Red with light	Blue	Blue with light	None
Output	None	Solid Red	Shaded Red	Solid Blue	Shaded Blue	Rendered Object

Key Moments - 3 Insights

Why does the unlit shader show no shading or highlights?

Because unlit shaders skip lighting calculations as shown in execution_table rows 1 and 3, they apply color directly without considering lights.

How does the lit shader change the object's appearance?

Lit shaders calculate lighting based on scene lights and surface normals (rows 2 and 4), which modulates the base color to add shading and highlights.

Can unlit shaders respond to scene lighting?

No, unlit shaders ignore lighting calculations entirely (rows 1 and 3), so they always show flat colors regardless of lights.

Visual Quiz - 3 Questions

Look at the execution_table, what is the lighting calculation result at step 3?

A Calculated based on lights

B Partial calculation

C Skipped

D Unknown

💡 Hint

Check the 'Lighting Calculation' column at step 3 in the execution_table

At which step does the object first show shading and highlights?

A Step 2

B Step 1

C Step 3

D Step 5

💡 Hint

Look for 'Calculated' lighting and 'Shaded' output in execution_table

If we change the unlit shader color to green, which execution_table row would change?

A Row 4

B Row 1

C Row 2

D Row 5

💡 Hint

Unlit shader color is shown in row 1 under 'Color Applied'

Concept Snapshot

Unlit shaders skip lighting and show flat colors.
Lit shaders calculate lighting for shading and highlights.
Unlit is simpler and faster but less realistic.
Lit shaders respond to scene lights and normals.
Choose unlit for flat style, lit for realism.

Full Transcript

This visual trace compares unlit and lit shaders in Unity. When rendering an object, the system picks a shader type. Unlit shaders skip lighting calculations and apply color directly, so objects appear flat and solid colored. Lit shaders calculate lighting using scene lights and surface normals, which modulates the base color to add shading and highlights. The execution table shows steps where unlit shaders skip lighting and apply color directly, while lit shaders calculate lighting before applying color. Variables like shader type, lighting calculation, and output color change step by step. Key moments clarify why unlit shaders show no shading and how lit shaders add realism. The quiz tests understanding of lighting calculation steps and color application. The snapshot summarizes that unlit shaders are simpler and faster but less realistic, while lit shaders respond to lights for realistic effects.