OpenGL Digit Sphere

A real-time 3D sphere rendered entirely from numeric digits, built with legacy OpenGL and WinAPI. The sphere rotates continuously with digits mapped across its surface using spherical coordinates.

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Preview

Digits in teal (RGB 0, 0.545, 0.545) scatter across a rotating sphere. Each digit's value is derived from its 3D position on the sphere surface.

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Features

• Spherical surface sampling — vertices generated via nested phi × theta loops
• Digit-mapped surface — each vertex value computed as |x + y + z| × 10 mod 10
• Bitmap font rendering — uses wglUseFontBitmaps with Courier New Bold 18px
• Orthographic projection — 16:9 aspect ratio at 1920×1080 resolution
• Smooth real-time rotation — X axis +0.3°/frame, Y axis +0.5°/frame (~60fps via Sleep(16))
• Teal digit coloring — glColor3f(0.0, 0.545, 0.545)

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Requirements

• Windows OS (WinAPI required)
• OpenGL 1.x — fixed-function pipeline (no shaders needed)
• MSVC or MinGW compiler
• Libraries: opengl32, gdi32, user32

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Build & Run

Since everything is unified into a single file, you only need to compile one source file.

Requirements: Windows OS, MinGW/MSVC compiler, and standard Windows libraries (opengl32, gdi32, user32).

MinGW / g++

g++ start.cpp -o startall.exe -DUNICODE -D_UNICODE -lopengl32 -lgdi32 -luser32
./startall.exe

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File Structure

opengl-digit-sphere/
├── circlenum.cpp       
└── README.md
└── squarechange.cpp
└── start.cpp

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How It Works

1. Window & OpenGL context dibuat menggunakan WinAPI (WNDCLASS, wglCreateContext)
2. Font bitmap di-generate via wglUseFontBitmaps lalu disimpan dalam display list
3. Setiap frame, display() dipanggil — menghitung posisi (x, y, z) tiap digit dari koordinat bola (phi, theta)
4. Digit ditampilkan di posisi 3D menggunakan glRasterPos3f + glCallLists
5. Rotasi diupdate setiap iterasi loop utama sebelum SwapBuffers

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Configuration

Kamu bisa ubah parameter berikut di circlenum.cpp:

Parameter	Default	Keterangan
radius	0.6f	Radius bola
angleX +=	0.3f	Kecepatan rotasi sumbu X
angleY +=	0.5f	Kecepatan rotasi sumbu Y
phi/theta step	0.12f	Kerapatan digit di permukaan
Font size	-18	Ukuran font (negatif = pixel height)
Sleep(16)	16ms	Target ~60fps

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Controls

The application starts with a blank canvas. Use the following keys to interact:

• C : Render Sphere mode.
• S : Render Cube mode.
• Spacebar : Clear screen (Empty mode).

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Known Limitations

• Menggunakan OpenGL fixed-function pipeline (legacy) — tidak kompatibel dengan OpenGL Core Profile
• itoa() adalah fungsi non-standard (tersedia di MSVC & MinGW, tidak di GCC Linux)
• Tidak ada depth sorting untuk digit — urutan render mengikuti loop, bukan jarak kamera
• Window size hardcoded ke 1920×1080

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License

MIT License.

Update in last month