🎨 Computer Graphics Projects

This repository contains two OpenGL-based Computer Graphics coursework projects developed for Computer Graphics.
Both assignments implement core rendering techniques, geometric modelling, transformations, animation, and interactive controls.

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📘 Project Overview

🖼 CW1 – 2D Greeting Card (OpenGL + GLUT)

A colourful interactive 2D greeting-card scene celebrating XJTLU’s anniversary.
The program showcases polygon rendering, parametric curves, geometric transformation, and animation.

✨ Key Features

• Custom background using multicolored polygons, with gradient achieved by color interpolation
• Text rendering supporting Chinese & English characters
• Billboard drawing using GL_FRONT / GL_BACK / GL_FILL / GL_LINE
• Circles & ellipses drawn via parametric equations
  • Circle: x = r cos(360t), y = r sin(360t)
  • Ellipse: x = a cos(360t), y = b sin(360t)
• Clouds, trees, balloons constructed from ellipses + circles
• Rainbow using glutSolidTorus() (showing half via translation)
• Geometric transformations: scaling, translation using glPushMatrix() & glPopMatrix()

🎮 Keyboard Controls

• q – Quit program
• f – Toggle between fill mode and line mode
• r – Reset animations
• o – Reverse direction of clouds & balloons
• t – Stop movement
• b / s – Scale objects bigger / smaller
• c – Restore original size

🖱 Mouse Interaction

• Left click: decelerate movement (if positive direction)
• Right click: accelerate movement

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🧱 CW2 – 3D Modelling Project (OpenGL + GLUT)

A hierarchical 3D scene including buildings, ground, trees, UFO animation, boat movement, and textured surfaces.
Demonstrates modelling, lighting, projection, and interactive navigation.

✨ Key Features

• Hierarchical modelling: ground, buildings, components built in structured layers
• Geometry creation using cubes, trapezoidal prisms, and glutSolidSphere
• Transformations for positioning, rotation, scaling of models
• Orthographic projection using glOrtho()
• Lighting & materials: ambient, diffuse, specular, shininess
• Texture mapping on roofs, grass, carpets
• Animation: UFO rotation/movement, boat navigation

🎮 Keyboard Controls

• q – Quit
• b / l / c – Scale trees bigger / smaller / reset
• w, a, s, d, h – Control boat movement
• t / r – Stop / reset UFO animation

⤴️ Special Keys

• Arrow keys ← ↑ ↓ →: rotate the entire model view
• PgUp, PgDn: zoom in / out

🖱 Mouse Interaction

• Left click: slow down if direction is positive, speed up if negative
• Right click: speed up if direction is positive, slow down if negative

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📂 Repository Structure

computer_graphics/
│
├── CW1/ # 2D Greeting Card project
├── CW2/ # 3D Modelling & Animation project
├── LICENSE
└── .gitattributes

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🛠 Build & Run Instructions

Both CW1 and CW2 require:

• OpenGL
• GLUT / FreeGLUT
• A C++ compiler supporting OpenGL linking

General compilation:

g++ main.cpp -lopengl32 -lglu32 -lfreeglut -o graphics_project
./graphics_project

(Modify filenames accordingly.)

🎯 Learning Outcomes

These projects demonstrate:

• Low-level 2D/3D rendering using OpenGL

• Parametric modelling & geometric construction

• Hierarchical and scene-based modelling

• Transformations, lighting, and texture mapping

• Interactive graphics programming