Java Software 3D Renderer

Built as a small experiment to understand how 3D rendering works without relying on OpenGL.

A simple 3D software renderer written in Java using Swing.

This project renders .obj models without OpenGL or external graphics libraries. Everything is implemented manually: transformations, triangle rasterization, z-buffering, and basic shading.

Features

• OBJ file loading
• Triangle rasterization
• Z-buffer (depth buffer)
• Per-face lighting (based on surface normal)
• Interactive rotation (mouse sliders)
• Load custom models at runtime
• Mesh subdivision ("inflate")

Demo

How it works

The renderer follows a basic 3D pipeline:

1. Load vertices and faces from an OBJ file
2. Apply rotation using 3x3 matrices
3. Project 3D coordinates to screen space (orthographic)
4. Rasterize triangles using barycentric coordinates
5. Use a z-buffer to handle depth
6. Compute simple shading using triangle normals

No GPU acceleration is used. All rendering is done on the CPU.

Controls

• Horizontal slider → rotate around Y axis
• Vertical slider → rotate around X axis
• "Open OBJ" → load a model from disk
• "Inflate" → subdivide the mesh

Running

Open the project in IntelliJ IDEA and run:

DemoViewer.java

Requires Java 8 or newer.

Project structure

src/
  DemoViewer.java     // UI + application setup
  RenderPanel.java    // rendering logic
  ObjLoader.java      // OBJ parsing
  Matrix3.java        // matrix math
  Vertex.java         // 3D point
  Triangle.java       // triangle data
models/
  *.obj               // example models

Notes

• Rendering is orthographic (no perspective projection)
• Large meshes may reduce performance (CPU rasterizer)
• OBJ support is minimal (only vertices and faces)

Future improvements

• Perspective projection
• Backface culling
• Wireframe mode
• Texture mapping

License

MIT