HelloWorld.cpp
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上传日期:2022-01-07
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- /*
- * Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
- *
- * 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 <cstdio>
- // 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);
- // Do we want to let bodies sleep?
- bool doSleep = true;
- // Construct a world object, which will hold and simulate the rigid bodies.
- b2World world(gravity, doSleep);
- // 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);
- // Clear applied body forces. We didn't apply any forces, but you
- // should know about this function.
- world.ClearForces();
- // Now print the position and angle of the body.
- b2Vec2 position = body->GetPosition();
- float32 angle = body->GetAngle();
- printf("%4.2f %4.2f %4.2fn", 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;
- }