From ab4d6f1d93b913a81ff11a854faab2286362c561 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nickg@pc022.cs.york.ac.uk>
Date: Fri, 5 Jun 2009 14:30:44 +0100
Subject: [PATCH] Use shared_ptr to manage asteroid display list

---
 src/Asteroid.cpp | 35 ++++++++++++++++++++++++++++++-----
 src/Asteroid.hpp |  7 ++++++-
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/src/Asteroid.cpp b/src/Asteroid.cpp
index bdd845e..f303333 100644
--- a/src/Asteroid.cpp
+++ b/src/Asteroid.cpp
@@ -23,8 +23,19 @@
 
 Texture* Asteroid::surfTexture[Surface::NUM_SURF_TEX];
 
+namespace {
+   // Called by shared_ptr when no more references to a display
+   // list are held
+   void displayListDeleter(GLuint* u)
+   {
+      glDeleteLists(*u, 1);
+      delete u;
+   }
+}
+
 Asteroid::Asteroid(int x, int y, int width, int surftex)
-   : StaticObject(x, y, width, 4)
+   : StaticObject(x, y, width, 4),
+     displayList_(new GLuint, displayListDeleter)
 {
    LOAD_ONCE {
       surfTexture[0] = new Texture("images/dirt_surface2.png");
@@ -33,7 +44,7 @@ Asteroid::Asteroid(int x, int y, int width, int surftex)
       surfTexture[3] = new Texture("images/rock_surface2.png");
    }
 
-   display_list = glGenLists(1);
+   *displayList_ = glGenLists(1);
    
    int change, texloop=0;
 
@@ -111,14 +122,22 @@ Asteroid::Asteroid(int x, int y, int width, int surftex)
    GenerateDisplayList(surftex);
 }
 
+Asteroid::Asteroid(const Asteroid& other)
+   : StaticObject(other),
+     displayList_(other.displayList_)
+{
+   copy(other.uppolys, other.uppolys + MAX_ASTEROID_WIDTH, uppolys);
+   copy(other.downpolys, other.downpolys + MAX_ASTEROID_WIDTH, downpolys);
+}
+
 Asteroid::~Asteroid()
 {
-   //glDeleteLists(display_list, 1);
+   
 }
 
 void Asteroid::GenerateDisplayList(int texidx)
 {
-   glNewList(display_list, GL_COMPILE);
+   glNewList(*displayList_, GL_COMPILE);
    
    glDisable(GL_BLEND);
    glEnable(GL_TEXTURE_2D);
@@ -184,12 +203,18 @@ LineSegment Asteroid::GetDownBoundary(int poly) const
 
 void Asteroid::Draw(int viewadjust_x, int viewadjust_y) const
 {
+   if (!displayList_) {
+      // This asteroid has been copied and lost its display
+      // list reference
+      throw runtime_error("Asteroid::Draw called on invalid asteroid copy");
+   }
+   
    double ix = xpos*OBJ_GRID_SIZE - viewadjust_x;
    double iy = ypos*OBJ_GRID_SIZE - viewadjust_y + OBJ_GRID_TOP;
 
    glLoadIdentity();
    glTranslated(ix, iy, 0.0);
-   glCallList(display_list);
+   glCallList(*displayList_);
 } 
 
 bool Asteroid::CheckCollision(const Ship& ship) const
diff --git a/src/Asteroid.hpp b/src/Asteroid.hpp
index 24eae05..c1db514 100644
--- a/src/Asteroid.hpp
+++ b/src/Asteroid.hpp
@@ -24,9 +24,14 @@
 #include "Surface.hpp"
 #include "ObjectGrid.hpp"
 
+#include <tr1/memory>
+
+using namespace std::tr1;
+
 class Asteroid : public StaticObject {
 public:
    Asteroid(int x, int y, int width, int surftex);
+   Asteroid(const Asteroid& other);
    ~Asteroid();
 	
    void Draw(int viewadjust_x, int viewadjust_y) const;
@@ -42,7 +47,7 @@ private:
    void GenerateDisplayList(int texidx);
 
    static Texture* surfTexture[Surface::NUM_SURF_TEX];
-   GLuint display_list;
+   shared_ptr<GLuint> displayList_;
    
    struct AsteroidSection {
       double texX, texwidth;
-- 
2.39.2