create Mode interface, move default mode into FadingLogosMode class

src/fading_logos_mode.d

@@ -0,0 +1,57 @@
+import derelict.opengl3.gl3;
+import gl3n.linalg;
+
+static import logo;
+import screensaver;
+import mode;
+import default_shader;
+
+class FadingLogosMode : Mode
+{
+    DefaultShader m_shader;
+
+    public void init(ScreenSaver ss)
+    {
+        glClearColor (0.0, 0.0, 0.0, 0.0);
+        glViewport(0, 0, ss.get_width(), ss.get_height());
+        m_shader = new DefaultShader();
+        m_shader.bind();
+    }
+
+    public void display(ScreenSaver ss, int ms)
+    {
+        mat4 view_matrix;
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        view_matrix.make_identity();
+        view_matrix.scale(ss.get_height() / cast(float)ss.get_width(), 1.0, 1.0);
+        double scale = 0.35 * ss.get_width() * 1080.0 / (ss.get_height() * 1920.0);
+        view_matrix.scale(scale, scale, scale);
+
+        glUniformMatrix4fv(m_shader.view_idx, 1, GL_TRUE, view_matrix.value_ptr);
+
+        for (int i = 0; i < N_GENTEX; i++)
+        {
+            draw_letter(logo.GENTEX, i);
+        }
+
+        for (int i = 0; i < N_CORPORATION; i++)
+        {
+            draw_letter(logo.CORPORATION, i);
+        }
+    }
+
+    protected void draw_letter(int word, int character)
+    {
+        float color[] =
+            (word == logo.GENTEX)
+            ? [0.0, 93.0/255.0, 171.0/255.0]
+            : [187.0/255.0, 188.0/255.0, 190.0/255.0];
+        glUniform3fv(m_shader.color_idx, 1, color.ptr);
+        logo.draw(logo.FACE, word, character, m_shader.position_idx);
+
+        color = [1.0, 1.0, 1.0];
+        glUniform3fv(m_shader.color_idx, 1, color.ptr);
+        logo.draw(logo.WIRE, word, character, m_shader.position_idx);
+    }
+}

src/gss.d

@@ -1,4 +1,7 @@
 import screensaver;
+import mode;
+
+import fading_logos_mode;
 
 extern(C) void GetDisplaySize(int * width, int * height, int * num_monitors);
 
@@ -11,7 +14,10 @@ int main()
         width = 1920 * 2;   /* restrict to two monitors */
 
     ScreenSaver ss = new ScreenSaver(width, height);
-    ss.run();
+    Mode modes[] = [
+        new FadingLogosMode(),
+    ];
+    ss.run(modes);
 
     return 0;
 }

src/mode.d

@@ -0,0 +1,16 @@
+import screensaver;
+
+interface Mode
+{
+    /**
+     * Initialize the ScreenSaver mode.
+     */
+    public void init(ScreenSaver ss);
+
+    /**
+     * Draw the screen.
+     *
+     * @param[in] ms Elapsed milliseconds since this mode was started.
+     */
+    public void display(ScreenSaver ss, int ms);
+}

src/screensaver.d

@@ -3,10 +3,9 @@ import derelict.sdl2.sdl;
 import derelict.opengl3.gl3;
 import glamour.vao;
 import glamour.vbo;
-import gl3n.linalg;
 
 static import logo;
-import default_shader;
+import mode;
 
 immutable int N_GENTEX = 6;
 immutable int N_CORPORATION = 11;
@@ -17,54 +16,6 @@ class ScreenSaver
     protected int m_height;
     protected SDL_Window * m_window;
     protected SDL_GLContext m_context;
-    DefaultShader m_shader;
-
-    protected void init()
-    {
-        glClearColor (0.0, 0.0, 0.0, 0.0);
-        glViewport(0, 0, m_width, m_height);
-        m_shader = new DefaultShader();
-        m_shader.bind();
-    }
-
-    protected void draw_letter(int word, int character)
-    {
-        float color[] =
-            (word == logo.GENTEX)
-            ? [0.0, 93.0/255.0, 171.0/255.0]
-            : [187.0/255.0, 188.0/255.0, 190.0/255.0];
-        glUniform3fv(m_shader.color_idx, 1, color.ptr);
-        logo.draw(logo.FACE, word, character, m_shader.position_idx);
-
-        color = [1.0, 1.0, 1.0];
-        glUniform3fv(m_shader.color_idx, 1, color.ptr);
-        logo.draw(logo.WIRE, word, character, m_shader.position_idx);
-    }
-
-    protected void display()
-    {
-        mat4 view_matrix;
-        glClear(GL_COLOR_BUFFER_BIT);
-
-        view_matrix.make_identity();
-        view_matrix.scale(m_height / cast(float)m_width, 1.0, 1.0);
-        double scale = 0.35 * m_width * 1080.0 / (m_height * 1920.0);
-        view_matrix.scale(scale, scale, scale);
-
-        glUniformMatrix4fv(m_shader.view_idx, 1, GL_TRUE, view_matrix.value_ptr);
-
-        for (int i = 0; i < N_GENTEX; i++)
-        {
-            draw_letter(logo.GENTEX, i);
-        }
-
-        for (int i = 0; i < N_CORPORATION; i++)
-        {
-            draw_letter(logo.CORPORATION, i);
-        }
-
-        SDL_GL_SwapWindow(m_window);
-    }
 
     this(int width, int height)
     {
@@ -106,9 +57,9 @@ class ScreenSaver
         logo.init();
     }
 
-    void run()
+    public void run(Mode modes[])
     {
-        init();
+        modes[0].init(this);
 
         SDL_Event event;
         for (;;)
@@ -118,7 +69,8 @@ class ScreenSaver
                 if ((event.type == SDL_QUIT) || (event.type == SDL_KEYDOWN))
                     break;
             }
-            display();
+            modes[0].display(this, SDL_GetTicks());
+            SDL_GL_SwapWindow(m_window);
         }
 
         SDL_GL_DeleteContext(m_context);
@@ -127,4 +79,14 @@ class ScreenSaver
 
         SDL_Quit();
     }
+
+    public int get_width()
+    {
+        return m_width;
+    }
+
+    public int get_height()
+    {
+        return m_height;
+    }
 }