add Widget module

src/Widget.cc

@@ -0,0 +1,23 @@
+#include "Widget.h"
+#include "ruby.h"
+#include "gl3w.h"
+
+static VALUE ruby_class;
+
+static VALUE Widget_render_begin(VALUE self)
+{
+    int x = FIX2INT(rb_iv_get(self, "@x"));
+    int y = FIX2INT(rb_iv_get(self, "@y"));
+    int width = FIX2INT(rb_iv_get(self, "@width"));
+    int height = FIX2INT(rb_iv_get(self, "@height"));
+
+    glViewport(x, y, width, height);
+
+    return Qnil;
+}
+
+void Widget_Init()
+{
+    ruby_class = rb_define_module("Widget");
+    rb_define_method(ruby_class, "render_begin", (VALUE(*)(...))Widget_render_begin, 0);
+}

src/Widget.h

@@ -0,0 +1,6 @@
+#ifndef WIDGET_H
+#define WIDGET_H
+
+void Widget_Init();
+
+#endif

src/main.cc

@@ -4,6 +4,7 @@
 #include "Font.h"
 #include "GLProgram.h"
 #include "GLShader.h"
+#include "Widget.h"
 #include "Window.h"
 
 using namespace std;
@@ -55,6 +56,7 @@ static int bootstrap()
     Font_Init();
     GLProgram_Init();
     GLShader_Init();
+    Widget_Init();
     Window_Init();
 
     rb_eval_string_protect(