s3de

Software 3d renderer for 3ds files.

The renderer, cmh3d, is a plain C library with no dependency on Windows. It draws through one callback, void pixel(int x, int y, int r, int g, int b), that the host hands it with Setppixel(), so it can render into anything: a window, a file, a terminal. Two hosts are included:

• s3de: the Win32 viewer (toolbar, settings dialog, mouse orbit).
• headless: a console program that renders a model to a .ppm image using only the C runtime. It is the smallest possible host and doubles as a check that the engine stays independent of the platform.
• tests: regression tests that render hand-built scenes and check pixels.

Models are loaded with the bundled lib3ds. Textures must be 24-bit .bmp files in the same folder as the .3ds file.

Building

Open s3de.sln in Visual Studio 2022 or later and build the x64 configuration, or from a developer prompt:

msbuild s3de.sln -p:Configuration=Release -p:Platform=x64

Headless host

x64\Release\headless.exe models\box05.3ds out.ppm

Optional arguments after the output name: shade flags as a hex number (see cmh3d/cmh3d/shade.h), rotation about x and y in degrees, zoom, and a camera position for a first-person view instead of an orbit. Run it without arguments for the usage line.

Tests

x64\Release\tests.exe

Prints one line per test and exits with the number of failures. The tests cover texture edge orientation and the exact-zero seam, specular state leaking between frames, the world-space light, vertex normal length, the Blinn-Phong highlight, the clipper's vertex count, binary-mode texture loading, repeated reloads, and bad input handling.

Writing a host

1. Setppixel(fn) with your pixel callback. The engine only calls it with x and y inside the screen; y grows upward.
2. InitializeWorld(filename) loads the model and sets up cameras and lights.
3. SetScreenW(w) and SetScreenH(h) whenever the output size changes.
4. Position the camera (see ProcessInput() in s3de/s3de.cpp or headless/headless.c) and call DrawScene(world) once per frame.
5. The engine never exits the process. InitializeWorld() returns NULL and DrawScene() returns 0 on failure, with the reason in GetLastEngineError(). After a successful load a non-empty message is a warning, such as a texture that could not be read.