JSDL: Jens’ Simple SDL — Features & ExamplesJSDL (Jens’ Simple SDL) is a lightweight, minimal wrapper around the Simple DirectMedia Layer (SDL) designed to make common tasks — window creation, event handling, basic rendering, and simple audio — easy and quick to implement. It aims at hobbyists, rapid prototypers, and educators who want to get small interactive programs running without the ceremony or complexity of larger frameworks.
Why JSDL exists
Many beginners and quick-prototype projects need just a thin, stable layer over SDL to reduce boilerplate. SDL itself is powerful but requires repeated setup for window/context creation, event loops, and resource management. JSDL provides convenient defaults and small helper functions so users can focus on their application logic rather than setup details.
Core features
- Minimal setup: One or two function calls to initialize video, audio, and input subsystems.
- Cross-platform: Works anywhere SDL works (Windows, macOS, Linux, and potentially other platforms supported by SDL).
- Event abstraction: Simplified event handling that exposes common events (keyboard, mouse, quit) in an easy-to-use structure.
- Simple rendering helpers: Basic drawing primitives (clear screen, draw rectangle, draw texture) with sensible defaults.
- Texture management: Lightweight API to load textures from image files and manage lifetimes.
- Basic audio playback: Play short sound effects and music with simple calls.
- Timing utilities: Frame limiting and delta-time helpers for stable updates.
- Examples and templates: Ready-made example programs for games, tools, and demos.
Typical API overview
Note: this is an illustrative API to show the style JSDL promotes.
- jsdl_init(flags)
- jsdl_create_window(title, width, height)
- jsdl_load_texture(path)
- jsdl_play_sound(path)
- jsdl_poll_events(callback)
- jsdl_draw_rect(x, y, w, h, color)
- jsdl_present()
- jsdl_delay(ms)
- jsdl_shutdown()
Example: Minimal “Hello Window” (C-style pseudocode)
#include "jsdl.h" int main() { jsdl_init(JS_DLL_VIDEO); Window *win = jsdl_create_window("Hello JSDL", 800, 600); bool running = true; while (running) { jsdl_poll_events(&running); // sets running = false on quit jsdl_clear(0, 0, 0, 255); jsdl_draw_text("Hello JSDL", 100, 100, WHITE); jsdl_present(); jsdl_delay(16); } jsdl_destroy_window(win); jsdl_shutdown(); return 0; } Example: Simple sprite movement
Texture *player = jsdl_load_texture("player.png"); float x = 100, y = 100; while (running) { Event e; while (jsdl_poll_event(&e)) { if (e.type == KEYDOWN) { if (e.key == KEY_LEFT) x -= 5; if (e.key == KEY_RIGHT) x += 5; if (e.key == KEY_UP) y -= 5; if (e.key == KEY_DOWN) y += 5; } } jsdl_clear(20, 20, 40, 255); jsdl_draw_texture(player, x, y); jsdl_present(); jsdl_delay(16); } Handling input
JSDL simplifies input by translating SDL events into a compact Event struct with fields like type, key, mouse_x, mouse_y, button, and so on. It provides helper functions for polling all events at once or handling them via a callback.
Resource management
JSDL emphasizes simple ownership patterns: functions that create resources return handles and corresponding destroy/free functions are provided. It also supplies convenience wrappers that automatically free on shutdown if the user prefers minimal code.
Audio basics
Play a short sound effect:
jsdl_play_sound("click.wav"); Play background music (streamed):
Music *m = jsdl_play_music("bgm.ogg", true); // loop jsdl_stop_music(m); Timing and fixed-step updates
JSDL includes utilities for fixed-step game loops:
const double dt = 1.0 / 60.0; double accumulator = 0.0; double current = jsdl_get_time(); while (running) { double newTime = jsdl_get_time(); double frameTime = newTime - current; current = newTime; accumulator += frameTime; while (accumulator >= dt) { update_physics(dt); accumulator -= dt; } render(); } Example projects and templates
- Basic Pong clone (single-file template)
- Tilemap viewer with camera pan/zoom
- Simple particle system demo
- Tooling: sprite atlas packer example using the JSDL image loader
Pros and cons
| Pros | Cons |
|---|---|
| Very low boilerplate | Less feature-rich than full engines |
| Easy for teaching and prototyping | Not optimized for large-scale projects |
| Small API surface | Depends on SDL; underlying complexity still exists |
| Cross-platform | Fewer community resources than major frameworks |
When to use JSDL
- Learning game programming fundamentals
- Rapid prototyping and game jams
- Small tools and utilities that need a GUI or input
- Educational tutorials where simplicity speeds learning
When not to use JSDL
- Large commercial titles needing advanced rendering, physics, or networking
- Projects that require high-level editor tooling and asset pipelines
- Cases where long-term maintainability and feature expansion outweigh minimalism
Extending JSDL
Because it’s thin, JSDL is easy to extend. Typical extensions include:
- Adding OpenGL/Vulkan backend support
- Integrating a higher-level UI toolkit
- Adding a resource hot-reloading system
- Integrating scripting languages (Lua/Python)
Final notes
JSDL’s goal is to be uncomplicated and predictable: a frictionless bridge from concept to running program. Its small API and sensible defaults make it a useful tool for beginners and quick experiments.
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