OpenGTU — Open Graphics Terminal Unit

A pseudo-3D ASCII rendering engine for the terminal, written in C.

Quick start

make run

Controls

Key	Action
W / S	Move forward / backward (free-fly) or zoom (orbit)
A / D	Strafe left / right
Q / E	Move up / down
Arrow keys	Look around (free-fly) or orbit (fixed)
F1	Toggle wireframe mode
F2	Toggle debug overlay
F3	Cycle shading profile
ESC	Quit

Configuration (include/config.h)

(everything here is set by defualt)

Macro	Default	Description
FPS	60	Target render framerate
__GTR	100	Simulation tick rate
__physicsEnabled	1	Toggle physics
camera	1	0=fixed orbit, 1=free-fly
SCREEN_WIDTH/HEIGHT	120×40	Viewport size
WIREFRAME_MODE	0	Global wireframe
DEBUG_OVERLAY	1	FPS/info bar

Shading profiles

Cycle with F3 at runtime, or call directly in code:

obj->shading = __retu_gst();         // default
obj->shading = __retu_gst_dense();
obj->shading = __retu_gst_minimal();
obj->shading = __retu_gst_classic();
obj->shading = __retu_gst_smooth();

Custom voxel shapes

static const int my_shape[] = {
    1,1,1,
    1,0,1,
    1,1,1,
};
Object *obj = scene_add_object(&scene, SHAPE_CUSTOM, pos, rot, scl);
obj->vox_w = 3; obj->vox_h = 3; obj->vox_d = 1;
memcpy(obj->voxels, my_shape, sizeof(my_shape));
object_build_mesh(obj);

Scene save / load

# The running engine saves to a .gtus file; load it:
./opengtu my_scene.gtus

File layout

OpenGTU/
├── include/
│   ├── config.h       Engine configuration macros
│   ├── math3d.h       Vector & matrix math
│   ├── graphics.h     Shading profiles & framebuffer
│   ├── object.h       Object, mesh & scene system
│   ├── camera.h       Camera (fixed / free-fly)
│   ├── physics.h      Physics (gravity, collision)
│   ├── input.h        Non-blocking keyboard input
│   ├── renderer.h     Rasteriser & renderer
│   ├── animation.h    Keyframe animation system
│   └── scene_io.h     Scene save / load (.gtus)
└── src/
    ├── main.c         Engine loop & demo scene
    ├── math3d.c
    ├── graphics.c
    ├── object.c
    ├── camera.c
    ├── physics.c
    ├── input.c
    ├── renderer.c
    ├── animation.c
    └── scene_io.c