GeoCLI

GeoCLI is a command-line computational geometry utility toolkit written in C++.
It is developed as a capstone project for a C++ Programming Fundamentals course and is inspired by the design philosophy of libraries such as CGAL.

The project focuses on clean structure, validated input, modular design, and reproducible builds, rather than advanced templates or heavy abstractions.

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📐 Project Goals

• Apply core C++ programming fundamentals in a complete project
• Practice modular, multi-file program structure
• Implement foundational computational geometry algorithms
• Demonstrate proper input validation and error handling
• Understand and use the C++ compilation pipeline (.cpp → .o → binary)
• Maintain a clear debugging and error-logging workflow

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🧰 Utility Overview

Each GeoCLI utility follows the same workflow:

User input → Validation → Geometric computation → Output

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1️⃣ Distance Between Points

Computes distances between two points in 2D space.

Inputs

• Point A: (x₁, y₁)
• Point B: (x₂, y₂)

a) Euclidean Distance

Calculates the straight-line distance between two points:

distance = sqrt((x₂ − x₁)² + (y₂ − y₁)²)

Use cases

• Geometric measurements
• Nearest-neighbor queries
• Spatial analysis

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b) Squared Distance

Computes the squared Euclidean distance without using a square root:

distance² = (x₂ − x₁)² + (y₂ − y₁)²

Why this matters

• Faster computation
• Avoids unnecessary floating-point operations
• Commonly used in geometry algorithms

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2️⃣ Orientation Test (Geometric Predicate)

Determines the relative orientation of three points.

Inputs

• Point A (x₁, y₁)
• Point B (x₂, y₂)
• Point C (x₃, y₃)

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a) Orientation of Three Points

Uses a signed cross product to classify orientation:

value = (x₂ − x₁)(y₃ − y₁) − (y₂ − y₁)(x₃ − x₁)

Interpretation

• value > 0 → Counterclockwise
• value < 0 → Clockwise
• value = 0 → Collinear

Why this matters

• Core predicate in computational geometry
• Used in convex hulls and intersection algorithms

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b) Point Relative to a Line

Determines whether a point lies:

• to the left of a directed line
• to the right
• or on the line

Optionally computes the perpendicular distance from the point to the line.

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3️⃣ Line Segment Intersection

Determines whether two line segments intersect in 2D.

Inputs

• Segment AB
• Segment CD

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a) Intersection Test (Yes / No)

Checks whether the two segments intersect using orientation tests and special collinearity cases.

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b) Intersection Classification

Classifies the type of interaction:

• No intersection
• Proper intersection
• Endpoint touching
• Collinear overlap

Use cases

• Collision detection
• Map overlays
• Computational geometry pipelines

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4️⃣ Polygon Tools

Analyzes basic geometric properties of polygons.

Inputs

• Number of vertices n ≥ 3
• Vertices (x₀, y₀)…(xₙ₋₁, yₙ₋₁) in order

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a) Polygon Area (Shoelace Formula)

Computes polygon area using:

area = ½ |Σ (xᵢ yᵢ₊₁ − yᵢ xᵢ₊₁)|

Applications

• GIS
• CAD
• Spatial statistics

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b) Polygon Orientation & Perimeter

• Determines clockwise or counterclockwise vertex order
• Computes the polygon perimeter

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🧱 Project Structure

GeoCLI/ ├── include/ # Header files ├── src/ # Source files ├── build/ # Compiled binaries (ignored by Git) ├── logs/ # Error and build logs ├── README.md ├── Makefile └── .gitignore

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🔐 Input Validation

All user input is validated through centralized CLI helper functions:

• read_int(...)
• read_double(...)
• read_choice(...)

This prevents crashes due to invalid input and keeps the code clean and reusable.

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🛠️ Build Instructions

Compile the project from the root directory:

g++ -std=c++17 -Wall -Wextra -pedantic -Iinclude src/*.cpp -o build/geocli