From f4841d64ecd49e47adf96afdc3155f3ebb72b3b4 Mon Sep 17 00:00:00 2001
From: Sam Hocevar <sam@hocevar.net>
Date: Thu, 18 Aug 2011 06:44:38 +0000
Subject: [PATCH] emitter: fix wrong velocity value computation in the
 particles.

---
 src/emitter.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/emitter.cpp b/src/emitter.cpp
index 184924d9..4777ef75 100644
--- a/src/emitter.cpp
+++ b/src/emitter.cpp
@@ -54,8 +54,10 @@ void Emitter::TickGame(float deltams)
 {
     for (int i = 0; i < data->nparticles; i++)
     {
-        data->velocities[i] = data->velocities[i] + deltams * data->gravity;
-        data->positions[i] = data->positions[i] + deltams * data->velocities[i];
+        vec3 oldvelocity = data->velocities[i];
+        data->velocities[i] += deltams * data->gravity;
+        data->positions[i] += deltams * 0.5f
+                                      * (oldvelocity + data->velocities[i]);
         if (data->positions[i].y < -100)
         {
             data->particles[i] = data->particles[data->nparticles - 1];