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C++ SFML Box2D DebugDraw

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DebugDraw.hpp

C++copy raw

// Debug draw for Box2D 2.2.1 - 2.3.0 for SFML 2.0 - SFMLDebugDraw.h
// Copyright (C) 2013  Matija Lovrekovic
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#ifndef SFMLDEBUGDRAW_H
#define SFMLDEBUGDRAW_H

#include <box2d/box2d.h>
#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include <cmath>

namespace sfdd
{
	const float SCALE = 32.f;
}

class SFMLDebugDraw : public b2Draw
{
private:
	sf::RenderWindow* m_window;
public:
	SFMLDebugDraw(sf::RenderWindow &window);

virtual ~SFMLDebugDraw() { }

/// Convert Box2D's OpenGL style color definition[0-1] to SFML's color definition[0-255], with optional alpha byte[Default - opaque]
	static sf::Color GLColorToSFML(const b2Color &color, sf::Uint8 alpha = 255)
	{
		return sf::Color(static_cast<sf::Uint8>(color.r * 255), static_cast<sf::Uint8>(color.g * 255), static_cast<sf::Uint8>(color.b * 255), alpha);
	}

/// Convert Box2D's vector to SFML vector [Default - scales the vector up by SCALE constants amount]
	static sf::Vector2f B2VecToSFVec(const b2Vec2 &vector, bool scaleToPixels = true)
	{
		return sf::Vector2f(vector.x * (scaleToPixels ? sfdd::SCALE : 1.f), vector.y * (scaleToPixels ? sfdd::SCALE : 1.f));
	}

/// Draw a closed polygon provided in CCW order.
	void DrawPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color);

/// Draw a solid closed polygon provided in CCW order.
	void DrawSolidPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color);

/// Draw a circle.
	void DrawCircle(const b2Vec2& center, float radius, const b2Color& color);

/// Draw a solid circle.
	void DrawSolidCircle(const b2Vec2& center, float radius, const b2Vec2& axis, const b2Color& color);

/// Draw a line segment.
	void DrawSegment(const b2Vec2& p1, const b2Vec2& p2, const b2Color& color);

/// Draw a transform. Choose your own length scale.
	void DrawTransform(const b2Transform& xf);

void DrawPoint(const b2Vec2& p, float size, const b2Color& color);
};
#endif //SFMLDEBUGDRAW_H

DebugDraw.cpp

C++copy raw

// Debug draw for Box2D 2.2.1 - 2.3.0 for SFML 2.0 - SFMLDebugDraw.cpp
// Copyright (C) 2013  Matija Lovrekovic
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#include "DebugDraw.hpp"

SFMLDebugDraw::SFMLDebugDraw(sf::RenderWindow &window) : m_window(&window) {}

void SFMLDebugDraw::DrawPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color) 
{
	sf::ConvexShape polygon(vertexCount);
	sf::Vector2f center;
	for(int i = 0; i < vertexCount; i++)
	{
		//polygon.setPoint(i, SFMLDraw::B2VecToSFVec(vertices[i]));
		sf::Vector2f transformedVec = SFMLDebugDraw::B2VecToSFVec(vertices[i]);
		polygon.setPoint(i, sf::Vector2f(std::floor(transformedVec.x), std::floor(transformedVec.y))); // flooring the coords to fix distorted lines on flat surfaces
	}																								   // they still show up though.. but less frequently
	polygon.setOutlineThickness(-1.f);
	polygon.setFillColor(sf::Color::Transparent);
	polygon.setOutlineColor(SFMLDebugDraw::GLColorToSFML(color));

m_window->draw(polygon);
}
void SFMLDebugDraw::DrawSolidPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color) 
{
	sf::ConvexShape polygon(vertexCount);
	for(int i = 0; i < vertexCount; i++)
	{
		//polygon.setPoint(i, SFMLDraw::B2VecToSFVec(vertices[i]));
		sf::Vector2f transformedVec = SFMLDebugDraw::B2VecToSFVec(vertices[i]);
		polygon.setPoint(i, sf::Vector2f(std::floor(transformedVec.x), std::floor(transformedVec.y))); // flooring the coords to fix distorted lines on flat surfaces
	}																								   // they still show up though.. but less frequently
	polygon.setOutlineThickness(-1.f);
	polygon.setFillColor(SFMLDebugDraw::GLColorToSFML(color, 60));
	polygon.setOutlineColor(SFMLDebugDraw::GLColorToSFML(color));

m_window->draw(polygon);
}
void SFMLDebugDraw::DrawCircle(const b2Vec2& center, float radius, const b2Color& color) 
{
	sf::CircleShape circle(radius * sfdd::SCALE);
	circle.setOrigin(radius * sfdd::SCALE, radius * sfdd::SCALE);
	circle.setPosition(SFMLDebugDraw::B2VecToSFVec(center));
	circle.setFillColor(sf::Color::Transparent);
	circle.setOutlineThickness(-1.f);
	circle.setOutlineColor(SFMLDebugDraw::GLColorToSFML(color));

m_window->draw(circle);
}
void SFMLDebugDraw::DrawSolidCircle(const b2Vec2& center, float radius, const b2Vec2& axis, const b2Color& color) 
{
	sf::CircleShape circle(radius * sfdd::SCALE);
	circle.setOrigin(radius * sfdd::SCALE, radius * sfdd::SCALE);
	circle.setPosition(SFMLDebugDraw::B2VecToSFVec(center));
	circle.setFillColor(SFMLDebugDraw::GLColorToSFML(color, 60));
	circle.setOutlineThickness(1.f);
	circle.setOutlineColor(SFMLDebugDraw::GLColorToSFML(color));

b2Vec2 endPoint = center + radius * axis;
	sf::Vertex line[2] = 
	{
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(center), SFMLDebugDraw::GLColorToSFML(color)),
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(endPoint), SFMLDebugDraw::GLColorToSFML(color)),
	};

m_window->draw(circle);
	m_window->draw(line, 2, sf::Lines);
}
void SFMLDebugDraw::DrawSegment(const b2Vec2& p1, const b2Vec2& p2, const b2Color& color) 
{
	sf::Vertex line[] =
	{
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(p1), SFMLDebugDraw::GLColorToSFML(color)),
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(p2), SFMLDebugDraw::GLColorToSFML(color))
	};

m_window->draw(line, 2, sf::Lines);
}
void SFMLDebugDraw::DrawTransform(const b2Transform& xf) 
{
	float lineLength = 0.4;

/*b2Vec2 xAxis(b2Vec2(xf.p.x + (lineLength * xf.q.c), xf.p.y + (lineLength * xf.q.s)));*/
	b2Vec2 xAxis = xf.p + lineLength * xf.q.GetXAxis();
	sf::Vertex redLine[] = 
	{
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(xf.p), sf::Color::Red),
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(xAxis), sf::Color::Red)
	};

// You might notice that the ordinate(Y axis) points downward unlike the one in Box2D testbed
	// That's because the ordinate in SFML coordinate system points downward while the OpenGL(testbed) points upward
	/*b2Vec2 yAxis(b2Vec2(xf.p.x + (lineLength * -xf.q.s), xf.p.y + (lineLength * xf.q.c)));*/
	b2Vec2 yAxis = xf.p + lineLength * xf.q.GetYAxis();
	sf::Vertex greenLine[] = 
	{
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(xf.p), sf::Color::Green),
		sf::Vertex(SFMLDebugDraw::B2VecToSFVec(yAxis), sf::Color::Green)
	};

m_window->draw(redLine, 2, sf::Lines);
	m_window->draw(greenLine, 2, sf::Lines);
}

void SFMLDebugDraw::DrawPoint(const b2Vec2& p, float size, const b2Color& color)
{

}

main.cpp

C++copy raw

#include <SFML/System.hpp>
#include <SFML/Graphics.hpp>
#include <box2d/box2d.h>
#include <vector>
#include <sstream>

#include "DebugDraw.hpp"

class QueryCallback : public b2QueryCallback
{
public:
	QueryCallback(const b2Vec2& point)
	{
		m_point = point;
		m_fixture = NULL;
	}

bool ReportFixture(b2Fixture* fixture)
	{
		b2Body* body = fixture->GetBody();
		if (body->GetType() == b2_dynamicBody)
		{
			bool inside = fixture->TestPoint(m_point);
			if (inside)
			{
				m_fixture = fixture;

return false;
			}
		}

return true;
	}

b2Vec2 m_point;
	b2Fixture* m_fixture;
};

//Converts SFML's vector to Box2D's vector and downscales it so it fits Box2D's MKS units
template<typename T > 
b2Vec2 sfVecToB2Vec(sf::Vector2<T> vector)
{
	return b2Vec2(vector.x / sfdd::SCALE, vector.y / sfdd::SCALE);
}

//Creates a box body and returns a reference to it
b2Body* createSquare(b2World &world, sf::RenderWindow &window)
{
	b2BodyDef bodyDef;
	bodyDef.type = b2_dynamicBody;
	bodyDef.position = sfVecToB2Vec(sf::Mouse::getPosition(window));
	b2Body* body = world.CreateBody(&bodyDef);

b2PolygonShape boxShape;
	boxShape.SetAsBox(0.5f, 0.5f, b2Vec2(0.f, 0.f), 0);
	body->CreateFixture(&boxShape, 1.f);
	
	return body;
}

//Creates a circle body and returns a reference to it
b2Body* createCircle(b2World &world, sf::RenderWindow &window)
{
	b2BodyDef bodyDef;
	bodyDef.type = b2_dynamicBody;
	bodyDef.position = sfVecToB2Vec(sf::Mouse::getPosition(window));
	b2Body* body = world.CreateBody(&bodyDef);

b2CircleShape circleShape;
	circleShape.m_radius = 0.5f;
	circleShape.m_p.SetZero();
	body->CreateFixture(&circleShape, 1.f);

return body;
}

int main()
{
	/* Create window and limit the framerate */
	sf::RenderWindow window(sf::VideoMode(1024,768, 32), "Box2D - SFML Debug Draw Test");
	window.setFramerateLimit(60);

/* Initialize font */
	sf::Font mainFont;
	if(!mainFont.loadFromFile("assets/Ubuntu-Regular.ttf")) // Set path to your font
	{
		return 1;
	}

/* Initialize debug text */
	sf::Text fpsCounter;
	fpsCounter.setFont(mainFont);
	fpsCounter.setFillColor(sf::Color::White);

sf::Text helpText;
	helpText.setFont(mainFont);
	helpText.setFillColor(sf::Color::White);
	helpText.setCharacterSize(20);
	helpText.setPosition(static_cast<float>(window.getSize().x) - static_cast<float>(window.getSize().x/ 2.f), 0.f  );

std::string helpTextString = std::string("Press 1 to spawn a box\n") +
		                         std::string("Press 2 to spawn a ball\n") +
								 std::string("Press backspace to remove the most recent body\n") +
							     std::string("Press F1 to enable/disable drawing of shapes\n") +
								 std::string("Press F2 to enable/disable drawing of AABB's\n") +
								 std::string("Press F3 to enable/disable drawing of center of gravity for objects\n") +
								 std::string("Press Tab to show/hide this text");

helpText.setString(helpTextString);

/* Create a stringstream for conversion purposes */
	std::stringstream sstream;

/* Create physical world and set it's gravity */
	b2World world(b2Vec2(0.f, 10.f));
	world.SetAllowSleeping(true);

/* Initialize SFML Debug Draw */
	SFMLDebugDraw debugDraw(window);

world.SetDebugDraw(&debugDraw);

/* Set initial flags for what to draw */
	debugDraw.SetFlags(b2Draw::e_shapeBit); //Only draw shapes

/* constants for time step and physics accuracy */
	const float timeStep = 1.0f / 60.0f;
	const int velocityIterations = 6;
	const int positionIterations = 2;

/* Create the bounding box */
	b2BodyDef boundingBoxDef;
	boundingBoxDef.type = b2_staticBody;
	float xPos = (window.getSize().x / 2.f) / sfdd::SCALE;
	float yPos = 0.5f;
	boundingBoxDef.position.Set(xPos, yPos);

b2Body* boundingBoxBody = world.CreateBody(&boundingBoxDef);

b2PolygonShape boxShape;
	boxShape.SetAsBox((window.getSize().x) / sfdd::SCALE, 0.5f, b2Vec2(0.f, 0.f), 0.f);
	boundingBoxBody->CreateFixture(&boxShape, 1.0); //Top

yPos = (window.getSize().y) / sfdd::SCALE - 1.f;
	boxShape.SetAsBox((window.getSize().x) / sfdd::SCALE, 0.5f, b2Vec2(0.f, yPos), 0.f);
	boundingBoxBody->CreateFixture(&boxShape, 1.f); //Bottom

xPos -= 0.5f;
	boxShape.SetAsBox(0.5f, (window.getSize().y) / sfdd::SCALE, b2Vec2(-xPos, 0.f), 0.f);
	boundingBoxBody->CreateFixture(&boxShape, 1.f);//Left

boxShape.SetAsBox(0.5f, (window.getSize().y) / sfdd::SCALE, b2Vec2(xPos, 0.f), 0.f);
	boundingBoxBody->CreateFixture(&boxShape, 1.f);//Right

/* Mouse Joint */
	b2MouseJoint* mouseJoint = nullptr;
	b2BodyDef bodyDef;
	b2Body* ground = world.CreateBody(&bodyDef); //This is not the body of the bounding box
												 //This body exists to serve as an anchor point for the mouse joint

sf::Clock deltaClock; //Clock used to measure FPS

bool helpTextEnabled = true;

std::vector<b2Body*> bodies;
	while(window.isOpen())
	{
		sf::Time deltaTime = deltaClock.restart();
		sf::Event event;
		while(window.pollEvent(event))
		{
			if(event.type == sf::Event::Closed || (event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Escape))
				window.close();
			else if(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::F1)
			{
				if(debugDraw.GetFlags() & b2Draw::e_shapeBit) debugDraw.ClearFlags(b2Draw::e_shapeBit);
				else debugDraw.AppendFlags(b2Draw::e_shapeBit);
			}
			else if(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::F2)
			{
				if(debugDraw.GetFlags() & b2Draw::e_aabbBit) debugDraw.ClearFlags(b2Draw::e_aabbBit);
				else debugDraw.AppendFlags(b2Draw::e_aabbBit);
			}
			else if(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::F3)
			{
				if(debugDraw.GetFlags() & b2Draw::e_centerOfMassBit) debugDraw.ClearFlags(b2Draw::e_centerOfMassBit);
				else debugDraw.AppendFlags(b2Draw::e_centerOfMassBit);
			}
			else if(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Tab)
			{
				if(helpTextEnabled) helpTextEnabled = false;
				else helpTextEnabled = true;
			}
			else if(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Num1)
			{
				bodies.push_back(createSquare(world, window));
			}
			else if(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::Num2)
			{
				bodies.push_back(createCircle(world, window));
			}
			else if(event.type == sf::Event::KeyPressed && event.key.code == sf::Keyboard::BackSpace)
			{
				if(!bodies.empty())
				{
					world.DestroyBody(bodies.back());
					bodies.pop_back();
				}
			}
			// Following three events are copied almost completely from http://code.google.com/p/box2d/source/browse/trunk/Box2D/Testbed/Framework/Test.cpp
			// Copyright (c) 2011 Erin Catto http://box2d.org
			else if(event.type == sf::Event::MouseButtonPressed && event.mouseButton.button == sf::Mouse::Left && mouseJoint == nullptr)
			{
				b2Vec2 mousePos = sfVecToB2Vec(sf::Mouse::getPosition(window));

// Make a small box.
				b2AABB aabb;
				b2Vec2 d;
				d.Set(0.001f, 0.001f);
				aabb.lowerBound = mousePos + d;
				aabb.upperBound = mousePos - d;

// Query the world for overlapping shapes.
				QueryCallback callback(mousePos);
				world.QueryAABB(&callback, aabb);

if (callback.m_fixture)
				{
					b2Body* body = callback.m_fixture->GetBody();
					b2MouseJointDef md;
					md.bodyA = ground; //If bounding box body is used instead, the dynamic bodes can be dragged over the bounding box and we don't want that
					md.bodyB = body;
					md.target = mousePos;
					md.maxForce = 1000.0f * body->GetMass();
					mouseJoint = (b2MouseJoint*)world.CreateJoint(&md);
					body->SetAwake(true);
				}
			}
			else if(event.type == sf::Event::MouseMoved && mouseJoint != nullptr)
			{
				b2Vec2 mousePos = sfVecToB2Vec(sf::Mouse::getPosition(window));
				mouseJoint->SetTarget(mousePos);
			}
			else if(event.type == sf::Event::MouseButtonReleased && event.mouseButton.button == sf::Mouse::Left && mouseJoint != nullptr)
			{
				world.DestroyJoint(mouseJoint);
				mouseJoint = nullptr;
			}
		}
		window.clear();
		world.Step(timeStep,velocityIterations,positionIterations);

{//Display FPS
			sstream.precision(0);
			sstream << std::fixed << "FPS: " << 1.f / deltaTime.asSeconds();
			fpsCounter.setString(sstream.str());
			window.draw(fpsCounter);
			sstream.str("");
		}

if (helpTextEnabled)
		{
			window.draw(helpText);
		}

world.DebugDraw();

window.display();
	}

return 0;
}

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