Added Box2D

external/Box2D-2.3.1/Box2D/HelloWorld/HelloWorld.cpp

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+/*
+* Copyright (c) 2006-2007 Erin Catto http://www.box2d.org
+*
+* This software is provided 'as-is', without any express or implied
+* warranty.  In no event will the authors be held liable for any damages
+* arising from the use of this software.
+* Permission is granted to anyone to use this software for any purpose,
+* including commercial applications, and to alter it and redistribute it
+* freely, subject to the following restrictions:
+* 1. The origin of this software must not be misrepresented; you must not
+* claim that you wrote the original software. If you use this software
+* in a product, an acknowledgment in the product documentation would be
+* appreciated but is not required.
+* 2. Altered source versions must be plainly marked as such, and must not be
+* misrepresented as being the original software.
+* 3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include <Box2D/Box2D.h>
+
+#include <stdio.h>
+
+// This is a simple example of building and running a simulation
+// using Box2D. Here we create a large ground box and a small dynamic
+// box.
+// There are no graphics for this example. Box2D is meant to be used
+// with your rendering engine in your game engine.
+int main(int argc, char** argv)
+{
+	B2_NOT_USED(argc);
+	B2_NOT_USED(argv);
+
+	// Define the gravity vector.
+	b2Vec2 gravity(0.0f, -10.0f);
+
+	// Construct a world object, which will hold and simulate the rigid bodies.
+	b2World world(gravity);
+
+	// Define the ground body.
+	b2BodyDef groundBodyDef;
+	groundBodyDef.position.Set(0.0f, -10.0f);
+
+	// Call the body factory which allocates memory for the ground body
+	// from a pool and creates the ground box shape (also from a pool).
+	// The body is also added to the world.
+	b2Body* groundBody = world.CreateBody(&groundBodyDef);
+
+	// Define the ground box shape.
+	b2PolygonShape groundBox;
+
+	// The extents are the half-widths of the box.
+	groundBox.SetAsBox(50.0f, 10.0f);
+
+	// Add the ground fixture to the ground body.
+	groundBody->CreateFixture(&groundBox, 0.0f);
+
+	// Define the dynamic body. We set its position and call the body factory.
+	b2BodyDef bodyDef;
+	bodyDef.type = b2_dynamicBody;
+	bodyDef.position.Set(0.0f, 4.0f);
+	b2Body* body = world.CreateBody(&bodyDef);
+
+	// Define another box shape for our dynamic body.
+	b2PolygonShape dynamicBox;
+	dynamicBox.SetAsBox(1.0f, 1.0f);
+
+	// Define the dynamic body fixture.
+	b2FixtureDef fixtureDef;
+	fixtureDef.shape = &dynamicBox;
+
+	// Set the box density to be non-zero, so it will be dynamic.
+	fixtureDef.density = 1.0f;
+
+	// Override the default friction.
+	fixtureDef.friction = 0.3f;
+
+	// Add the shape to the body.
+	body->CreateFixture(&fixtureDef);
+
+	// Prepare for simulation. Typically we use a time step of 1/60 of a
+	// second (60Hz) and 10 iterations. This provides a high quality simulation
+	// in most game scenarios.
+	float32 timeStep = 1.0f / 60.0f;
+	int32 velocityIterations = 6;
+	int32 positionIterations = 2;
+
+	// This is our little game loop.
+	for (int32 i = 0; i < 60; ++i)
+	{
+		// Instruct the world to perform a single step of simulation.
+		// It is generally best to keep the time step and iterations fixed.
+		world.Step(timeStep, velocityIterations, positionIterations);
+
+		// Now print the position and angle of the body.
+		b2Vec2 position = body->GetPosition();
+		float32 angle = body->GetAngle();
+
+		printf("%4.2f %4.2f %4.2f\n", position.x, position.y, angle);
+	}
+
+	// When the world destructor is called, all bodies and joints are freed. This can
+	// create orphaned pointers, so be careful about your world management.
+
+	return 0;
+}