/* * 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 #include using namespace std; // 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; }