Support enforcing aspect ratio independent of window buffer size

Author: einarf

demosys/conf/default_settings.py

@@ -23,11 +23,12 @@
 # Window size
 WINDOW = {
     "size": (1280, 720),
+    "aspect_ratio": 16 / 9,
     "fullscreen": False,
-    "resizable": False,
+    "resizable": True,
     "title": "demosys-py",
     "vsync": True,
-    "cursor": False,
+    "cursor": True,
 }
 
 MUSIC = None

demosys/opengl/fbo.py

@@ -1,25 +1,27 @@
 from OpenGL import GL
 from demosys.opengl import Texture
 
-# Reference to the window
-WINDOW = None
+WINDOW_FBO = None
 
 
 class WindowFBO:
     """
     Fake FBO representing default render target
     """
-    def __init__(self):
-        self.window = WINDOW
-        self.color_buffers = []
-        self.color_buffers_ids = []
-        self.depth_buffer = None
+    def __init__(self, window):
+        self.window = window
 
     def bind(self):
         """
         Sets the viewport back to the buffer size of the screen/window
         """
-        GL.glViewport(0, 0, WINDOW.buffer_width, WINDOW.buffer_height)
+        # The expected height with the current viewport width
+        expected_height = int(self.window.buffer_width / self.window.aspect_ratio)
+        # How much positive or negative y padding
+        blank_space = self.window.buffer_height - expected_height
+
+        GL.glViewport(0, int(blank_space / 2),
+                      self.window.buffer_width, expected_height)
 
     def release(self):
         """
@@ -34,9 +36,6 @@ def clear(self):
         pass
 
 
-WINDOW_FBO = WindowFBO()
-
-
 class FBO:
     """Frame buffer object"""
     def __init__(self):

demosys/view/controller.py

@@ -7,7 +7,6 @@
 from demosys.view.window import Window
 from demosys.effects.registry import Effect
 from demosys.opengl import fbo
-from demosys.opengl.fbo import WINDOW_FBO
 from demosys import resources
 from demosys.conf import settings
 from demosys.scene import camera
@@ -31,18 +30,19 @@ def run(manager=None):
 
     global WINDOW
     WINDOW = Window()
-    fbo.WINDOW = WINDOW
+
+    fbo.WINDOW_FBO = fbo.WindowFBO(WINDOW)
 
     print("Loader started at", glfw.get_time())
 
     # Inject attributes into the base Effect class
     Effect.window_width = WINDOW.buffer_width
     Effect.window_height = WINDOW.buffer_height
-    Effect.window_aspect = WINDOW.width / WINDOW.height
+    Effect.window_aspect = WINDOW.aspect_ratio
 
     # Set up the default system camera
     global CAMERA
-    CAMERA = camera.SystemCamera(aspect=Effect.window_aspect, fov=60.0, near=1, far=1000)
+    CAMERA = camera.SystemCamera(aspect=WINDOW.aspect_ratio, fov=60.0, near=1, far=1000)
     Effect.sys_camera = CAMERA
 
     # Initialize Effects
@@ -77,12 +77,13 @@ def run(manager=None):
 
         # Set the viewport as FBOs will change the values
         GL.glViewport(0, 0, WINDOW.buffer_width, WINDOW.buffer_height)
+
         # Clear the buffer
         GL.glClearColor(0.0, 0.0, 0.0, 0.0)
         GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT | GL.GL_STENCIL_BUFFER_BIT)
 
         # Tell the manager to draw stuff
-        manager.draw(t, ft, WINDOW_FBO)
+        manager.draw(t, ft, fbo.WINDOW_FBO)
 
         # Swap buffers and deal with events and statistics
         WINDOW.swap_buffers()

demosys/view/window.py

@@ -19,6 +19,7 @@ def __init__(self):
         self.height = settings.WINDOW['size'][1]
         self.resizable = settings.WINDOW.get('resizable') or False
         self.title = settings.WINDOW.get('title') or "demosys-py"
+        self.aspect_ratio = settings.WINDOW.get('aspect_ratio', 16 / 9)
 
         if not glfw.init():
             raise ValueError("Failed to initialize glfw")
@@ -70,8 +71,6 @@ def __init__(self):
         if not settings.WINDOW.get('cursor'):
             glfw.set_input_mode(self.window, glfw.CURSOR, glfw.CURSOR_DISABLED)
 
-        glfw.set_window_aspect_ratio(self.window, self.width, self.height)
-
         # Get the actual buffer size of the window
         # This is important for some displays like Apple's Retina as reported window sizes are virtual
         self.buffer_width, self.buffer_height = glfw.get_framebuffer_size(self.window)