add minimal SDL skeleton

in_one_weekend/build.zig

@@ -1,4 +1,5 @@
 const Builder = @import("std").build.Builder;
+const builtin = @import("std").builtin;
 
 pub fn build(b: *Builder) void {
     // Standard target options allows the person running `zig build` to choose
@@ -14,6 +15,10 @@ pub fn build(b: *Builder) void {
     const exe = b.addExecutable("in_one_weekend", "src/main.zig");
     exe.setTarget(target);
     exe.setBuildMode(mode);
+
+    exe.linkSystemLibrary("SDL2");
+    exe.linkSystemLibrary("c");
+
     exe.install();
 
     const run_cmd = exe.run();

in_one_weekend/src/main.zig

@@ -1,5 +1,70 @@
 const std = @import("std");
+const sdl = @cImport({
+    @cInclude("SDL.h");
+});
+
+// From: https://github.com/Nelarius/weekend-raytracer-zig/blob/master/src/main.zig
+// See https://github.com/zig-lang/zig/issues/565
+// SDL_video.h:#define SDL_WINDOWPOS_UNDEFINED         SDL_WINDOWPOS_UNDEFINED_DISPLAY(0)
+// SDL_video.h:#define SDL_WINDOWPOS_UNDEFINED_DISPLAY(X)  (SDL_WINDOWPOS_UNDEFINED_MASK|(X))
+// SDL_video.h:#define SDL_WINDOWPOS_UNDEFINED_MASK    0x1FFF0000u
+const SDL_WINDOWPOS_UNDEFINED = @bitCast(c_int, sdl.SDL_WINDOWPOS_UNDEFINED_MASK);
+
+const win_width = 640;
+const win_height = 320;
+const fps = 60;
 
 pub fn main() anyerror!void {
-    std.log.info("All your codebase are belong to us.", .{});
+    if (sdl.SDL_Init(sdl.SDL_INIT_VIDEO) != 0) {
+        std.log.err("Unable to initialize SDL: {}", .{sdl.SDL_GetError()});
+        return error.SDLInitializationFailed;
+    }
+    defer sdl.SDL_Quit();
+
+    const window = sdl.SDL_CreateWindow("Raytracing in One Weekend", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, win_width, win_height, sdl.SDL_WINDOW_OPENGL) orelse {
+        std.log.err("Unable to create window: {}", .{sdl.SDL_GetError()});
+        return error.SDLInitializationFailed;
+    };
+
+    const surface = sdl.SDL_GetWindowSurface(window) orelse {
+        std.log.err("Unable to get window surface: {}", .{sdl.SDL_GetError()});
+        return error.SDLInitializationFailed;
+    };
+
+    {
+        _ = sdl.SDL_LockSurface(surface);
+
+        var h: usize = 0;
+        while (h < win_height) {
+            var w: usize = 0;
+            while (w < win_width) {
+                // std.log.info("w = {}, h = {}", .{ w, h });
+                const index = w * 4 + h * @intCast(usize, surface.*.pitch);
+                const target_pixel = @ptrToInt(surface.*.pixels) + index;
+                @intToPtr(*u32, target_pixel).* = 0xffffffff;
+                w += 1;
+            }
+            h += 1;
+        }
+        defer sdl.SDL_UnlockSurface(surface);
+    }
+
+    if (sdl.SDL_UpdateWindowSurface(window) != 0) {
+        std.log.err("Error updating window surface: {}", .{sdl.SDL_GetError()});
+        return error.SDLUpdateWindowFailed;
+    }
+
+    var running = true;
+    while (running) {
+        var event: sdl.SDL_Event = undefined;
+        while (sdl.SDL_PollEvent(&event) != 0) {
+            switch (event.@"type") {
+                sdl.SDL_QUIT => {
+                    running = false;
+                },
+                else => {},
+            }
+        }
+        sdl.SDL_Delay(1000 / fps);
+    }
 }