Rectangle Border

Create a border by subtracting an inner rectangle mask from an outer one.

Overview

• Follow the steps to complete the exercise.

Learning Objectives

• Build rectangle masks with step
• Combine masks using subtraction

Prerequisites

• simple-rectangle
• step-function-mask

Key Concepts

• vUv is normalized UV in [0,1].

vec2 uv = vUv;

• Blend values with mix(a, b, t).

vec3 color = mix(colorA, colorB, t);

• Build a hard mask with step.

float mask = step(0.5, uv.x);

How To Implement (Step-by-step)

• Start from vUv.
• Build a hard mask with step().
• Use mix() to blend outputs.

Self-check

• Does it compile without errors?
• Does the output match the goal?
• Are key values kept in [0,1]?

Common Mistakes

• Clamp t into [0,1] when needed.