GraphicalLab

An interactive computer graphics laboratory built with Avalonia GraphicalLab is a cross-platform desktop application developed in C# using the Avalonia UI framework. It serves as an educational and experimental tool for visualizing classic computer graphics algorithms. The app provides dedicated interactive canvases for each major topic, with real-time rendering, step-by-step debug mode, grid overlay, and instant visual feedback via toast notifications.

✨ Features

Lines

• Draw line segments using three classic algorithms:
  • DDA (Digital Differential Analyzer)
  • Bresenham line algorithm
  • Xiaolin Wu anti-aliased line algorithm
• Click twice on the canvas to define start and end points

Circles & Conic Sections

• Draw the following primitives by clicking on the canvas:
  • Circle (parameter R)
  • Ellipse (parameters A, B)
  • Hyperbola (parameters A, B)
  • Parabola (parameter P)
• Automatic parameter visibility based on selected type

Curves

• Interactive curve construction using waypoints:
  • Hermite curves
  • Bézier curves
  • B-Splines
• Three interaction modes: Add, Remove, and Connect points
• Real-time redrawing when points are moved

Polygons

• Build arbitrary polygons point-by-point
• Convex hull algorithms:
  • Graham scan
  • Jarvis march (Gift wrapping)
• Point-in-polygon testing with real-time feedback
• Normal vector visualization (toggleable)
• Line segment intersection detection (with highlighted intersection points)

Polygon Filling

• Four advanced fill algorithms (works with polygons created in the Polygons tab):
  • Scanline with sorted edge list
  • Scanline with Active Edge Table (AET)
  • Simple flood fill (seed fill)
  • Scanline flood fill
• Click inside a closed polygon to fill it

3D Transformations

• Load 3D figures (supported formats via the figure loader service)
• Full suite of affine transformations:
  • Translation (Move in X/Y/Z)
  • Rotation (around X, Y, Z axes)
  • Scaling (uniform)
  • Reflection (flip over X/Y/Z)
  • Perspective projection toggle
• Keyboard shortcuts for quick manipulation (WASD, arrows, +/-, etc.)
• Real-time 3D-to-2D projection on the canvas

Triangulation & Voronoi

• Delaunay triangulation
• Voronoi diagram generation
• Add and drag points interactively
• Instant visual update of both diagrams

Common Controls (available on every page)

• Debug Mode — enables step-by-step algorithm execution
• Next Step button — advance one iteration (or bulk steps in some algorithms)
• Grid toggle — helpful coordinate grid
• Clear Canvas button
• Live step counter and status
• Toast notifications for successful operations and algorithm info
• MVVM architecture with CommunityToolkit for clean, maintainable code

Screenshots

Lines Page

Three line algorithms in action with anti-aliasing example

Circles & Conics Page

Circle, ellipse, hyperbola, and parabola drawn from a single click

Curves Page

Waypoint-based curve construction with live preview

Polygons & Convex Hulls

Graham and Jarvis hulls with normals and intersection testing

Filling Algorithms

Scanline and flood-fill results on complex polygons

3D Transformations

Loaded 3D model with rotation, scaling, and perspective projection

Triangulation & Voronoi

Interactive Delaunay triangulation and Voronoi diagram

Tech Stack

• Framework: Avalonia UI (cross-platform)
• Architecture: MVVM with CommunityToolkit.Mvvm
• Rendering: Custom WriteableBitmap + DebuggableBitmapControl
• Algorithms: Implemented in clean, separate modules (Lines, Circles, Curves, Fill, Poly, Transform, Voronoi, etc.)
• Notifications: Custom toast service
• Debugging: Step-by-step pixel drawing