From 014cff0b636303ea8a380002e56280bc76f0c153 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Thu, 11 Jun 2009 21:47:59 +0100
Subject: [PATCH] Sort the smoke particles again because it looks better

---
 src/Billboard.cpp  |  2 +-
 src/SmokeTrail.cpp | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/Billboard.cpp b/src/Billboard.cpp
index 1024ddd..24a880e 100644
--- a/src/Billboard.cpp
+++ b/src/Billboard.cpp
@@ -159,7 +159,7 @@ public:
 };
 
 void SphericalBillboard::render() const
-{
+{  
    // Based on code from
    // http://www.lighthouse3d.com/opengl/billboarding/index.php?billSphe
    Vector<float> lookAt, objToCamProj, upAux, objToCam;
diff --git a/src/SmokeTrail.cpp b/src/SmokeTrail.cpp
index 67d8ee3..0062133 100644
--- a/src/SmokeTrail.cpp
+++ b/src/SmokeTrail.cpp
@@ -50,7 +50,7 @@ private:
    void newParticle();
    bool moveParticle(Particle& aParticle, int aDelta);
    
-   list<Particle> myParticles; 
+   mutable list<Particle> myParticles; // Need to sort particles in render() 
    float myX, myY, myZ;
    IBillboardPtr myBillboard;
 
@@ -159,8 +159,19 @@ void SmokeTrail::newParticle()
    myParticles.push_back(p);
 }
 
+struct CmpDistanceToCam {
+   bool operator()(const SmokeTrail::Particle& lhs,
+                   const SmokeTrail::Particle& rhs)
+   {
+      return distanceToCamera(makeVector(lhs.x, lhs.y, lhs.z))
+         > distanceToCamera(makeVector(rhs.x, rhs.y, rhs.z));
+   }
+};
+
 void SmokeTrail::render() const
 {   
+   myParticles.sort(CmpDistanceToCam());
+ 
    for (list<Particle>::const_iterator it = myParticles.begin();
         it != myParticles.end(); ++it) {
       myBillboard->setPosition((*it).x, (*it).y, (*it).z);
-- 
2.39.2