– We store position and velocity as floats for smooth sub-pixel movement. The key addition in SDL3’s API is the use of SDL_GetTicks() returning Uint64 (milliseconds), which is far less prone to overflow than SDL2’s 32-bit value. Delta time calculation ensures the ball moves at a consistent speed regardless of frame rate.
// Update based on delta time Uint64 current_time = SDL_GetTicks(); float delta_time = (current_time - last_time) / 1000.0f; if (delta_time > 0.05f) delta_time = 0.05f; // clamp for safety last_time = current_time; sdl3 example
ball_x += velocity_x * delta_time; ball_y += velocity_y * delta_time; – We store position and velocity as floats
Introduction For decades, the Simple DirectMedia Layer (SDL) has been the silent workhorse of cross-platform game development and multimedia applications. From indie darlings like Celeste to AAA titles and emulators like RetroArch, SDL provides a unified interface to handle windows, input, graphics, and audio across Windows, macOS, Linux, iOS, and Android. In early 2024, the long-awaited SDL3 was released, bringing modernized APIs, better GPU integration, and a cleaner, more predictable programming model. This essay provides a complete, runnable example of an SDL3 application and dissects every component, demonstrating why SDL3 represents a significant evolution from its predecessors. The Big Picture: What SDL3 Changes Before diving into code, it is crucial to understand SDL3’s philosophical shift. SDL2 relied heavily on SDL_Surface for software rendering and SDL_Texture for hardware-accelerated 2D. Initialization was monolithic, and many functions returned -1 on error. SDL3 simplifies this: initialization is now explicit and fine-grained, many obsolete functions have been removed, and the new GPU API (not used in this basic example) offers low-overhead access to Vulkan, Metal, and Direct3D 12. Furthermore, SDL3 adopts a more consistent naming convention (e.g., SDL_CreateWindow remains, but many event and input functions have been renamed for clarity). Our example will focus on creating a window, handling basic events, and rendering a simple animated shape using the modernized 2D renderer. The Complete Example: An Animated Bouncing Ball Below is a complete, working SDL3 program written in C. It opens an 800x600 window, creates a renderer, and animates a blue ball bouncing off the window’s edges. The code assumes SDL3 development libraries are installed (e.g., via vcpkg, Homebrew, or source compilation). // Update based on delta time Uint64 current_time
// Bounce off edges (with radius adjustment) if (ball_x - BALL_RADIUS < 0) { ball_x = BALL_RADIUS; velocity_x = -velocity_x; } else if (ball_x + BALL_RADIUS > WINDOW_WIDTH) { ball_x = WINDOW_WIDTH - BALL_RADIUS; velocity_x = -velocity_x; } if (ball_y - BALL_RADIUS < 0) { ball_y = BALL_RADIUS; velocity_y = -velocity_y; } else if (ball_y + BALL_RADIUS > WINDOW_HEIGHT) { ball_y = WINDOW_HEIGHT - BALL_RADIUS; velocity_y = -velocity_y; }
– SDL_SetRenderDrawColor sets the drawing color. SDL_RenderClear fills the whole window with black. We then draw a filled rectangle (representing the ball) in blue. Note: SDL3’s renderer still does not include a native filled circle primitive, so a rectangle suffices for demonstration. Finally, SDL_RenderPresent swaps the buffers to show the frame.
– SDL3 has renamed many event types. The quit event is now SDL_EVENT_QUIT (instead of SDL_QUIT ). Key events follow a similar pattern: SDL_EVENT_KEY_DOWN and the key code is accessed via event.key.key (where SDLK_ESCAPE is unchanged). The event loop is non-blocking thanks to SDL_PollEvent .
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