add hello world example and edit source tree

examples/hello_world/main.cpp

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+/*
+* Copyright (c) 2016-2016 Irlan Robson http://www.irlan.net
+*
+* 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 <bounce\bounce.h>
+
+// We don't care for a profiler. This definition does nothing.
+bool b3PushProfileScope(const char* name)
+{
+	return false;
+}
+
+// We don't care for a profiler. This definition does nothing.
+void b3PopProfileScope()
+{
+	
+}
+
+// This example shows how to setup and run a simple simulation 
+// using Bounce. 
+int main(int argc, char** argv)
+{
+	// The world gravity.
+	const b3Vec3 gravity(0.0f, -9.8f, 0.0f);
+	
+	// The fixed time step size.
+	const float32 timeStep = 1.0f / 60.0f;
+	
+	// Number of iterations for the velocity constraint solver.
+	const u32 velocityIterations = 8;
+
+	// Number of iterations for the position constraint solver.
+	const u32 positionIterations = 2;
+
+	// The world-> We allocate it using the heap but you can to it 
+	// on the stack if the stack is sufficiently large.
+	b3World* world = new b3World();
+	world->SetGravity(gravity);
+
+	// Create a static ground body at the world origin.
+	b3BodyDef groundDef;
+	b3Body* ground = world->CreateBody(groundDef);
+
+	// Create a box positioned at the world origin and 
+	// aligned with the world frame.
+	b3BoxHull groundBox;
+	
+	// Set the ground box dimensions using a linear scale transform.
+	b3Transform scale;
+	scale.position.SetZero();
+	scale.rotation = b3Diagonal(10.0f, 1.0f, 10.0f);
+	groundBox.SetTransform(scale);
+	
+	// Create the box physics wrapper.
+	b3HullShape groundShape;
+	groundShape.m_hull = &groundBox;
+
+	// Add the box to the ground body.
+	b3ShapeDef groundBoxDef;
+	groundBoxDef.shape = &groundShape;
+	ground->CreateShape(groundBoxDef);
+
+	// Create a dynamic body.
+	b3BodyDef bodyDef;
+	bodyDef.type = e_dynamicBody;
+	
+	// Position the body 10 meters high from the world origin.
+	bodyDef.position.Set(0.0f, 10.0f, 0.0f);
+	
+	// Set the initial angular velocity to pi radians (180 degrees) per second.
+	bodyDef.angularVelocity.Set(0.0f, B3_PI, 0.0f);
+	
+	b3Body* body = world->CreateBody(bodyDef);
+
+	// Create a unit box positioned at the world origin and 
+	// aligned with the world frame.
+	b3BoxHull bodyBox;
+	bodyBox.SetIdentity();
+
+	// Create the box physics wrapper.
+	b3HullShape bodyShape;
+	bodyShape.m_hull = &bodyBox;
+
+	// Add the box to the body.
+	b3ShapeDef bodyBoxDef;
+	bodyBoxDef.shape = &bodyShape;
+	bodyBoxDef.density = 1.0f;
+	body->CreateShape(bodyBoxDef);
+
+	// Run a small game loop of 60 frames length.
+	for (u32 i = 0; i < 60; ++i)
+	{
+		// Perform a time step of the world in this frame.
+		world->Step(timeStep, velocityIterations, positionIterations);
+		
+		// Read the body position and orientation in this frame.
+		b3Vec3 position = body->GetPosition();
+		b3Quat orientation = body->GetOrientation();
+		
+		// Decode the axis and angle of rotation about it from the quaternion.
+		b3Vec3 axis;
+		float32 angle;
+		orientation.GetAxisAngle(&axis, &angle);
+
+		// Visualize the body state in this frame.
+		printf("position = %.2f %.2f %.2f\n", position.x, position.y, position.z);
+		printf("axis = %.2f %.2f %.2f, angle = %.2f\n\n", axis.x, axis.y, axis.z, angle);
+	}
+	
+	// Now destroy the bodies since the world manages their lifetime.
+	delete world;
+
+	return 0;
+}