From: mathnerd314 <mathnerd314@837edb03-e0f3-0310-88ca-d4d4e8b29345>
Date: Sat, 27 Feb 2010 13:00:42 +0000 (+0000)
Subject: Some documentation for physic and what it does
X-Git-Url: https://git.verplant.org/?a=commitdiff_plain;h=60aba159b1f94d46bc2f3bebc0818c5bc5be956b;p=supertux.git

Some documentation for physic and what it does

git-svn-id: http://supertux.lethargik.org/svn/supertux/trunk/supertux@6417 837edb03-e0f3-0310-88ca-d4d4e8b29345
---

diff --git a/src/supertux/physic.cpp b/src/supertux/physic.cpp
index 02132350e..729e0be13 100644
--- a/src/supertux/physic.cpp
+++ b/src/supertux/physic.cpp
@@ -152,6 +152,9 @@ Physic::get_movement(float elapsed_time)
 {
   float grav = gravity_enabled_flag ? (Sector::current()->get_gravity() * gravity_modifier * 100.0f) : 0;
 
+  // Semi-implicit Euler integration
+  // with constant acceleration, this will result in a position delta of
+  // v t + .5 a t (t+elapsed_time) at total time t
   vx += ax * elapsed_time;
   vy += (ay + grav) * elapsed_time;
   Vector result(vx * elapsed_time, vy * elapsed_time);