From 46e842c7cc2e977f9bdd9fb4480dac26163fa25b Mon Sep 17 00:00:00 2001
From: Patrik Gornicz <Gornicz.P@gmail.com>
Date: Thu, 21 Aug 2008 16:29:27 -0400
Subject: [PATCH] created a gravity well

---
 src/Effects/GravityWell.cpp | 50 +++++++++++++++++++++++++++++++++++++++++++++
 src/Effects/GravityWell.h   | 39 +++++++++++++++++++++++++++++++++++
 src/Effects/Screen.cpp      |  8 ++++----
 src/Makefile                |  1 +
 src/effectManager.cpp       |  8 ++++++--
 5 files changed, 100 insertions(+), 6 deletions(-)
 create mode 100644 src/Effects/GravityWell.cpp
 create mode 100644 src/Effects/GravityWell.h

diff --git a/src/Effects/GravityWell.cpp b/src/Effects/GravityWell.cpp
new file mode 100644
index 0000000..4fcd446
--- /dev/null
+++ b/src/Effects/GravityWell.cpp
@@ -0,0 +1,50 @@
+/*
+ *  Copyright (C) 2008 Patrik Gornicz, Gornicz_P (at) hotmail (dot) com.
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "GravityWell.h"
+#include "../Entities/PhysicsEntity.h"
+
+
+/// ***** Constructors/Destructors *****
+
+GravityWell::GravityWell(const Vector2& pos)
+    : position(pos)
+{
+
+}
+GravityWell::~GravityWell()
+{
+
+}
+
+/// ***** Public Class Methods *****
+
+Vector2 GravityWell::forceDelta(const PhysicsEntity* e, float) const
+{
+    const Vector2& pos = e->positionRaw();
+    float mass = e->mass;
+
+    Vector2 delta = position - pos;
+    float sqrDist = delta.sqrLength();
+
+    Vector2 acc(0,0);
+
+    if( sqrDist > 0.5F )
+        acc += delta / sqrDist * mass;
+
+    return acc;
+}
diff --git a/src/Effects/GravityWell.h b/src/Effects/GravityWell.h
new file mode 100644
index 0000000..36b9dec
--- /dev/null
+++ b/src/Effects/GravityWell.h
@@ -0,0 +1,39 @@
+/*
+ *  Copyright (C) 2008 Patrik Gornicz, Gornicz_P (at) hotmail (dot) com.
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef GRAVITYWELL_H
+#define GRAVITYWELL_H
+
+#include "Effect.h"
+#include "../Vector2.h"
+
+
+/// ***** Header Class *****
+
+class GravityWell: public Effect
+{
+  public:
+    GravityWell(const Vector2& pos);
+    ~GravityWell();
+
+    Vector2 forceDelta(const PhysicsEntity*, float) const;
+
+  private:
+    Vector2 position;
+};
+
+#endif // GRAVITYWELL_H
diff --git a/src/Effects/Screen.cpp b/src/Effects/Screen.cpp
index e4ef901..61108c4 100644
--- a/src/Effects/Screen.cpp
+++ b/src/Effects/Screen.cpp
@@ -47,16 +47,16 @@ Vector2 Screen::positionDelta(const PhysicsEntity* e, float time_step) const
         radius = b->getRadius();
 
 
-    if(pos.y > 600-radius && velo.y > 0)
+    if(pos.y > 600-radius)
         acc.y += 600-radius - pos.y;
 
-    if(pos.y < 0+radius && velo.y < 0)
+    if(pos.y < 0+radius)
         acc.y += 0+radius - pos.y;
 
-    if(pos.x > 800-radius && velo.x > 0)
+    if(pos.x > 800-radius)
         acc.x += 800-radius - pos.x;
 
-    if(pos.x < 0+radius && velo.x < 0)
+    if(pos.x < 0+radius)
         acc.x += 0+radius - pos.x;
 
     return acc;
diff --git a/src/Makefile b/src/Makefile
index 3ed4b86..b04d5cd 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -43,6 +43,7 @@ SRCS += GameStates/Running.cpp
 
 SRCS += Effects/Effect.cpp
 SRCS += Effects/Gravity.cpp
+SRCS += Effects/GravityWell.cpp
 SRCS += Effects/Screen.cpp
 
 SRCS += config/config.cpp
diff --git a/src/effectManager.cpp b/src/effectManager.cpp
index d4c07e5..6ebffdd 100644
--- a/src/effectManager.cpp
+++ b/src/effectManager.cpp
@@ -19,8 +19,11 @@
 
 #include "Effects/Effect.h"
 #include "Effects/Gravity.h"
+#include "Effects/GravityWell.h"
 #include "Effects/Screen.h"
 
+#include "Vector2.h"
+
 /// ***** Private Variables *****
 
 Effect** effects;
@@ -30,11 +33,12 @@ int numEffects;
 
 void effect::init()
 {
-    numEffects = 2;
+    numEffects = 3;
     effects = new Effect*[numEffects]();
 
     effects[0] = new Gravity();
-    effects[1] = new Screen();
+    effects[1] = new GravityWell(Vector2(400,400));
+    effects[2] = new Screen();
 }
 void effect::clean()
 {
-- 
2.10.2