add skeleton gui sources

Makefile

@@ -2,6 +2,10 @@
 default:
 	@rake $@
 
+.PHONY: gui
+gui:
+	@rake $@
+
 .PHONY: test
 test:
 	@rake $@

Rakefile.rb

@@ -22,6 +22,11 @@ end
 
 task :gui => :library do
   base_env.clone(clone: :all) do |env|
+    env["CFLAGS"] += `sdl2-config --cflags`.split(" ")
+    env["CXXFLAGS"] += `sdl2-config --cflags`.split(" ")
+    env["LDCMD"] += `sdl2-config --libs`.split(" ")
+    env["LIBS"] += ["dl", "GL"]
+    env.Program("^/jes", Dir["src/gui/**/*.{cc,c}"])
   end
 end
 

src/gui/main.cc

@@ -0,0 +1,75 @@
+#include "gl3w.h"
+#include <SDL.h>
+#include <iostream>
+
+using namespace std;
+
+#define WIDTH   500
+#define HEIGHT  500
+
+void init(void)
+{
+    glClearColor (0.0, 0.0, 0.0, 0.0);
+}
+
+void display(SDL_Window * window)
+{
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    SDL_GL_SwapWindow(window);
+}
+
+int main(int argc, char *argv[])
+{
+    if (SDL_Init(SDL_INIT_VIDEO))
+    {
+        cerr << "Failed to initialize SDL!" << endl;
+        return 1;
+    }
+
+    atexit(SDL_Quit);
+
+    SDL_Window * window = SDL_CreateWindow(argv[0],
+                                           SDL_WINDOWPOS_UNDEFINED,
+                                           SDL_WINDOWPOS_UNDEFINED,
+                                           WIDTH,
+                                           HEIGHT,
+                                           SDL_WINDOW_OPENGL);
+    if (!window)
+    {
+        cerr << "Failed to create window!" << endl;
+        SDL_Quit();
+        return 2;
+    }
+
+    SDL_GLContext gl_context = SDL_GL_CreateContext(window);
+
+    if (gl3wInit() != 0)
+    {
+        cerr << "Failed to gl3wInit()" << endl;
+        SDL_Quit();
+        return 2;
+    }
+
+    if (!gl3wIsSupported(3, 0))
+    {
+        cerr << "OpenGL 3.0 is not supported!" << endl;
+        SDL_Quit();
+        return 2;
+    }
+
+    init();
+    display(window);
+    SDL_Event event;
+    while (SDL_WaitEvent(&event))
+    {
+        if (event.type == SDL_QUIT)
+            break;
+        else if (event.type == SDL_KEYDOWN)
+        {
+            if (event.key.keysym.sym == SDLK_ESCAPE)
+                break;
+            if (event.key.keysym.sym == SDLK_RETURN)
+                display(window);
+        }
+    }
+}