From 136c7bfde8e46e83a29ac9459a819019653ea9ac Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Mon, 7 Apr 2014 22:16:19 -0400
Subject: [PATCH] implement hello world

from http://bulletphysics.org/mediawiki-1.5.8/index.php/Hello_World
---
 .gitignore |  1 +
 Makefile   |  4 ++++
 main.cc    | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 main.cc

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..95811e0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/main
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5a736b4
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,4 @@
+all: main
+
+main: main.cc
+	g++ -o $@ $$(pkg-config --cflags bullet) $^ $$(pkg-config --libs bullet)
diff --git a/main.cc b/main.cc
new file mode 100644
index 0000000..28dcb52
--- /dev/null
+++ b/main.cc
@@ -0,0 +1,62 @@
+#include <iostream>
+#include <btBulletDynamicsCommon.h>
+
+int main(int argc, char *argv[])
+{
+    btBroadphaseInterface * broadphase = new btDbvtBroadphase();
+    btDefaultCollisionConfiguration * collision_configuration = new btDefaultCollisionConfiguration();
+    btCollisionDispatcher * dispatcher = new btCollisionDispatcher(collision_configuration);
+    btSequentialImpulseConstraintSolver * solver = new btSequentialImpulseConstraintSolver;
+    btDiscreteDynamicsWorld * dynamics_world = new btDiscreteDynamicsWorld(dispatcher, broadphase, solver, collision_configuration);
+    dynamics_world->setGravity(btVector3(0, -9.8, 0));
+
+    btCollisionShape * ground_shape = new btStaticPlaneShape(btVector3(0, 1, 0), 1);
+    btCollisionShape * fall_shape = new btSphereShape(1);
+
+    btDefaultMotionState * ground_motion_state =
+        new btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1), btVector3(0, -1, 0)));
+    btRigidBody::btRigidBodyConstructionInfo
+        ground_rigid_body_ci(0, ground_motion_state, ground_shape, btVector3(0, 0, 0));
+    btRigidBody * ground_rigid_body = new btRigidBody(ground_rigid_body_ci);
+
+    dynamics_world->addRigidBody(ground_rigid_body);
+
+    btDefaultMotionState * fall_motion_state =
+        new btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1), btVector3(0, 50, 0)));
+
+    btScalar mass = 1;
+    btVector3 fall_inertia(0, 0, 0);
+    fall_shape->calculateLocalInertia(mass, fall_inertia);
+    btRigidBody::btRigidBodyConstructionInfo
+        fall_rigid_body_ci(mass, fall_motion_state, fall_shape, fall_inertia);
+    btRigidBody * fall_rigid_body = new btRigidBody(fall_rigid_body_ci);
+
+    dynamics_world->addRigidBody(fall_rigid_body);
+
+    for (int i = 0; i < 300; i++)
+    {
+        dynamics_world->stepSimulation(1.0 / 60.0, 10);
+
+        btTransform trans;
+        fall_rigid_body->getMotionState()->getWorldTransform(trans);
+
+        std::cout << "sphere height: " << trans.getOrigin().getY() << std::endl;
+    }
+
+    delete fall_rigid_body;
+    delete fall_motion_state;
+
+    delete ground_rigid_body;
+    delete ground_motion_state;
+
+    delete fall_shape;
+    delete ground_shape;
+
+    delete dynamics_world;
+    delete solver;
+    delete dispatcher;
+    delete collision_configuration;
+    delete broadphase;
+
+    return 0;
+}