From 8236efcffc8c43ad0c29ccf1d34f9dbd576389a5 Mon Sep 17 00:00:00 2001
From: Quantum <quantum2048@gmail.com>
Date: Sat, 26 Oct 2013 14:25:37 -0400
Subject: [PATCH] Added orbital display.

---
 punyverse/entity.py | 38 +++++++++++++++++++++++++++++++++++++-
 punyverse/game.py   |  6 ++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/punyverse/entity.py b/punyverse/entity.py
index 1274d51..b13d925 100644
--- a/punyverse/entity.py
+++ b/punyverse/entity.py
@@ -1,7 +1,8 @@
 from punyverse import framedata
-from math import radians, sin, cos
 from punyverse.orbit import KeplerOrbit
 
+from pyglet.gl import *
+
 
 class Entity(object):
     def __init__(self, id, location, rotation=(0, 0, 0), direction=(0, 0, 0), background=False):
@@ -60,11 +61,46 @@ class Satellite(Planet):
         longitude = kwargs.pop('longitude', 0)
         argument = kwargs.pop('argument', 0)
 
+        # Orbit calculation
+        self.orbit_id = None
+        self.orbit_cache = None
+
         self.theta = 0
         # OpenGL's z-axis is reversed
         self.orbit = KeplerOrbit(distance, eccentricity, inclination, longitude, argument)
         super(Satellite, self).__init__(*args, **kwargs)
 
+    def get_orbit(self):
+        # Cache key is the three orbital plane parameters and eccentricity
+        cache = (self.orbit.eccentricity, self.orbit.longitude, self.orbit.inclination, self.orbit.argument)
+        if self.orbit_cache == cache:
+            return self.orbit_id
+
+        print 'Orbit cache miss'
+        if self.orbit_id is not None:
+            glDeleteLists(self.orbit_id, 1)
+
+        id = glGenLists(1)
+        glNewList(id, GL_COMPILE)
+        glDisable(GL_LIGHTING)
+        glDisable(GL_TEXTURE_2D)
+        glPushAttrib(GL_LINE_BIT | GL_CURRENT_BIT)
+        glColor3f(0, 1, 0)
+        glLineWidth(3)
+        glBegin(GL_LINE_LOOP)
+        for theta in xrange(360):
+            x, z, y = self.orbit.orbit(theta)
+            glVertex3f(x, y, z)
+        glEnd()
+        glPopAttrib()
+        glEnable(GL_TEXTURE_2D)
+        glEnable(GL_LIGHTING)
+        glEndList()
+
+        self.orbit_id = id
+        self.orbit_cache = cache
+        return id
+
     def update(self):
         super(Planet, self).update()
 
diff --git a/punyverse/game.py b/punyverse/game.py
index 72ff54e..15d89cd 100644
--- a/punyverse/game.py
+++ b/punyverse/game.py
@@ -265,6 +265,12 @@ class Applet(pyglet.window.Window):
                 glDisable(GL_ALPHA_TEST)
                 glPopMatrix()
 
+            if self.debug and hasattr(entity, 'get_orbit') and hasattr(entity, 'parent'):
+                glPushMatrix()
+                glTranslatef(*entity.parent.location)
+                glCallList(entity.get_orbit())
+                glPopMatrix()
+
         glColor4f(1, 1, 1, 1)
         glDisable(GL_TEXTURE_2D)