basic SDL game loop in Zig

sdl_main.zig

const std = @import("std");
const warn = std.debug.warn;
const fmt = std.fmt;

const c = @cImport({
    @cInclude("SDL2/SDL.h");
});
const assert = @import("std").debug.assert;

const SDL_WINDOWPOS_UNDEFINED = @bitCast(c_int, c.SDL_WINDOWPOS_UNDEFINED_MASK);
const SDL_INIT_EVERYTHING =
    c.SDL_INIT_TIMER |
    c.SDL_INIT_AUDIO |
    c.SDL_INIT_VIDEO |
    c.SDL_INIT_EVENTS |
    c.SDL_INIT_JOYSTICK |
    c.SDL_INIT_HAPTIC |
    c.SDL_INIT_GAMECONTROLLER;

const INIT_WIDTH = 800;
const INIT_HEIGHT = 600;
const maxFps = 60;
const targetDt = 1000 / maxFps;

var keepRunning = true;

pub fn main() !void {
    if (c.SDL_Init(c.SDL_INIT_VIDEO) != 0) {
        c.SDL_Log(c"Unable to initialize SDL: %s", c.SDL_GetError());
        return error.SDLInitializationFailed;
    }
    defer c.SDL_Quit();

    const window = c.SDL_CreateWindow(c"Paint",
        SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
        @intCast(c_int, INIT_WIDTH), @intCast(c_int, INIT_HEIGHT),
        c.SDL_WINDOW_OPENGL | c.SDL_WINDOW_RESIZABLE)
    orelse {
        c.SDL_Log(c"Unable to create window: %s", c.SDL_GetError());
        return error.SDLInitializationFailed;
    };
    defer c.SDL_DestroyWindow(window);

    const renderer = c.SDL_CreateRenderer(window, -1, 0)
    orelse {
        c.SDL_Log(c"Unable to create renderer: %s", c.SDL_GetError());
        return error.SDLInitializationFailed;
    };
    defer c.SDL_DestroyRenderer(renderer);

    var t0 = @intCast(u32, c.SDL_GetTicks());
    var t1 = t0;
    var dt : f32 = 0.001 * @intToFloat(f32, targetDt);
    while(keepRunning)
    {
        var event : c.SDL_Event = undefined;
        while(c.SDL_PollEvent(&event) != 0) {
            switch(event.@"type") {
                c.SDL_QUIT => {
                    keepRunning = false;
                },
                else => {}
            }
        }

        t1 = @intCast(u32, c.SDL_GetTicks());
        const dtInt = t1 - t0;
        if(dtInt < targetDt) {
            c.SDL_Delay(targetDt - dtInt);
            dt = 0.001 * @intToFloat(f32, targetDt);
        }
        else {
            dt = 0.001 * @intToFloat(f32, t1 - t0);
        }
        t0 = t1;
    }
}