Box2dTest.cpp

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 Copyright (c) 2021 @aismann; Peter Eismann, Germany; dreifrankensoft

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#include "Box2dTest.h"
#include "../testResource.h"
#include "extensions/axmol-ext.h"
#include "renderer/Renderer.h"
#include "renderer/CustomCommand.h"

using namespace ax;
USING_NS_AX_EXT;

#define PTM_RATIO 32

enum
{
    kTagParentNode = 1,
};

Box2DTests::Box2DTests()
{
    ADD_TEST_CASE(Box2DTest);
}

std::string Box2DTest::title() const
{
    return "Box2D - Basic";
}

bool Box2DTest::init()
{
    if (!TestCase::init())
    {
        return false;
    }
    auto dispatcher = Director::getInstance()->getEventDispatcher();

    auto touchListener            = EventListenerTouchAllAtOnce::create();
    touchListener->onTouchesEnded = AX_CALLBACK_2(Box2DTest::onTouchesEnded, this);
    dispatcher->addEventListenerWithSceneGraphPriority(touchListener, this);

    // init physics
    this->initPhysics();
    // create reset button
    this->createResetButton();

    // Set up sprite
#if 1
    // Use batch node. Faster
    auto parent    = SpriteBatchNode::create("Images/blocks.png", 100);
    _spriteTexture = parent->getTexture();
#else
    // doesn't use batch node. Slower
    _spriteTexture = Director::getInstance()->getTextureCache()->addImage("Images/blocks.png");
    auto parent    = Node::create();
#endif
    addChild(parent, 0, kTagParentNode);

    addNewSpriteAtPosition(VisibleRect::center());

    auto label = Label::createWithTTF("Tap screen add boxes.\nSome objects be only visible with debug on.",
                                      "fonts/Marker Felt.ttf", 12.0f);
    addChild(label, 0);
    label->setColor(Color3B(0, 0, 255));
    label->setPosition(VisibleRect::center().x - 50, VisibleRect::top().y - 60);

    // menu for debug layer
    MenuItemFont::setFontSize(18);
    auto item = MenuItemFont::create("Toggle debug", AX_CALLBACK_1(Box2DTest::toggleDebugCallback, this));

    auto menu = Menu::create(item, nullptr);
    this->addChild(menu);
    menu->setPosition(VisibleRect::right().x - 100, VisibleRect::top().y - 60);

    drawBox2D = g_debugDraw.GetDrawNode();
    addChild(drawBox2D, 100);
    drawBox2D->setOpacity(150);

    scheduleUpdate();

    return true;
}

Box2DTest::Box2DTest() : _spriteTexture(nullptr), world(nullptr) {}

Box2DTest::~Box2DTest()
{
    AX_SAFE_DELETE(world);
}

void Box2DTest::toggleDebugCallback(Object* sender)
{
    showDebugDraw = !showDebugDraw;
    drawBox2D->clear();
}

void Box2DTest::initPhysics()
{
    b2Vec2 gravity;
    gravity.Set(0.0f, -10.0f);
    world = new b2World(gravity);

    // Do we want to let bodies sleep?
    world->SetAllowSleeping(true);

    world->SetContinuousPhysics(true);

    // Define the ground body.
    b2BodyDef groundBodyDef;
    groundBodyDef.position.Set(0, 0);  // bottom-left corner

    // 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.
    b2EdgeShape groundBox;

    // bottom
    groundBox.SetTwoSided(b2Vec2(VisibleRect::leftBottom().x / PTM_RATIO, VisibleRect::leftBottom().y / PTM_RATIO),
                          b2Vec2(VisibleRect::rightBottom().x / PTM_RATIO, VisibleRect::rightBottom().y / PTM_RATIO));
    groundBody->CreateFixture(&groundBox, 0);

    // top
    groundBox.SetTwoSided(b2Vec2(VisibleRect::leftTop().x / PTM_RATIO, VisibleRect::leftTop().y / PTM_RATIO),
                          b2Vec2(VisibleRect::rightTop().x / PTM_RATIO, VisibleRect::rightTop().y / PTM_RATIO));
    groundBody->CreateFixture(&groundBox, 0);

    // left
    groundBox.SetTwoSided(b2Vec2(VisibleRect::leftTop().x / PTM_RATIO, VisibleRect::leftTop().y / PTM_RATIO),
                          b2Vec2(VisibleRect::leftBottom().x / PTM_RATIO, VisibleRect::leftBottom().y / PTM_RATIO));
    groundBody->CreateFixture(&groundBox, 0);

    // right
    groundBox.SetTwoSided(b2Vec2(VisibleRect::rightBottom().x / PTM_RATIO, VisibleRect::rightBottom().y / PTM_RATIO),
                          b2Vec2(VisibleRect::rightTop().x / PTM_RATIO, VisibleRect::rightTop().y / PTM_RATIO));
    groundBody->CreateFixture(&groundBox, 0);

    // Small triangle
    b2Vec2 vertices[3];
    vertices[0].Set(-1.0f, 0.0f);
    vertices[1].Set(1.0f, 0.0f);
    vertices[2].Set(0.0f, 2.0f);

    b2PolygonShape polygon;
    polygon.Set(vertices, 3);

    b2FixtureDef triangleShapeDef;
    triangleShapeDef.shape   = &polygon;
    triangleShapeDef.density = 1.0f;

    b2BodyDef triangleBodyDef;
    triangleBodyDef.type = b2_dynamicBody;
    triangleBodyDef.position.Set(rand() % 13 + 3, 4);

    b2Body* body1 = world->CreateBody(&triangleBodyDef);
    body1->CreateFixture(&triangleShapeDef);

    // Large triangle (recycle definitions)
    vertices[0] *= 2.0f;
    vertices[1] *= 2.0f;
    vertices[2] *= 2.0f;
    polygon.Set(vertices, 3);

    triangleBodyDef.position.Set(rand() % 13 + 3, 4);

    b2Body* body2 = world->CreateBody(&triangleBodyDef);
    body2->CreateFixture(&triangleShapeDef);

    // Small box
    polygon.SetAsBox(1.0f, 0.5f);

    b2FixtureDef boxShapeDef;
    boxShapeDef.shape   = &polygon;
    boxShapeDef.density = 1.0f;

    b2BodyDef boxBodyDef;
    boxBodyDef.type = b2_dynamicBody;
    boxBodyDef.position.Set(rand() % 13 + 3, 4);

    b2Body* body3 = world->CreateBody(&boxBodyDef);
    body3->CreateFixture(&boxShapeDef);

    // Large box (recycle definitions)
    polygon.SetAsBox(2.0f, 1.0f);
    boxBodyDef.position.Set(rand() % 13 + 3, 4);

    b2Body* body4 = world->CreateBody(&boxBodyDef);
    body4->CreateFixture(&boxShapeDef);

    // Small circle
    b2CircleShape circle;
    circle.m_radius = 1.0f;

    b2FixtureDef circleShapeDef;
    circleShapeDef.shape   = &circle;
    circleShapeDef.density = 1.0f;

    b2BodyDef circleBodyDef;
    circleBodyDef.type = b2_dynamicBody;
    circleBodyDef.position.Set(rand() % 13 + 3, 4);

    b2Body* body5 = world->CreateBody(&circleBodyDef);
    body5->CreateFixture(&circleShapeDef);

    // Large circle
    circle.m_radius *= 2.0f;
    circleBodyDef.position.Set(rand() % 13 + 3, 4);

    b2Body* body6 = world->CreateBody(&circleBodyDef);
    body6->CreateFixture(&circleShapeDef);

    uint32 flags = 0;
    flags += 1 * b2Draw::e_shapeBit;
    flags += 1 * b2Draw::e_jointBit;
    flags += 0 * b2Draw::e_aabbBit;
    flags += 0 * b2Draw::e_centerOfMassBit;
    g_debugDraw.SetFlags(flags);
    g_debugDraw.mRatio          = PTM_RATIO;
    g_debugDraw.debugNodeOffset = {0, 0};
    world->SetDebugDraw(&g_debugDraw);
}

void Box2DTest::createResetButton()
{
    auto reset = MenuItemImage::create("Images/r1.png", "Images/r2.png",
                                       [&](Object* sender) { getTestSuite()->restartCurrTest(); });

    auto menu = Menu::create(reset, nullptr);

    menu->setPosition(VisibleRect::bottom().x, VisibleRect::bottom().y + 30);
    this->addChild(menu, -1);
}

void Box2DTest::addNewSpriteAtPosition(Vec2 p)
{
    AXLOGD("Add sprite x: {:.2} y: {:.2}", p.x, p.y);

    // Define the dynamic body.
    // Set up a 1m squared box in the physics world
    b2BodyDef bodyDef;
    bodyDef.type = b2_dynamicBody;
    bodyDef.position.Set(p.x / PTM_RATIO, p.y / PTM_RATIO);

    AXLOGD("Add PTM_RATIO sprite x: {:.2} y: {:.2}", p.x / PTM_RATIO, p.y / PTM_RATIO);

    b2Body* body = world->CreateBody(&bodyDef);

    // Define another box shape for our dynamic body.
    b2PolygonShape dynamicBox;
    dynamicBox.SetAsBox(.5f, .5f);  // These are mid points for our 1m box

    // Define the dynamic body fixture.
    b2FixtureDef fixtureDef;
    fixtureDef.shape    = &dynamicBox;
    fixtureDef.density  = 1.0f;
    fixtureDef.friction = 0.3f;
    body->CreateFixture(&fixtureDef);

    auto parent = this->getChildByTag(kTagParentNode);

    // We have a 64x64 sprite sheet with 4 different 32x32 images.  The following code is
    // just randomly picking one of the images
    int idx     = (AXRANDOM_0_1() > .5 ? 0 : 1);
    int idy     = (AXRANDOM_0_1() > .5 ? 0 : 1);
    auto sprite = PhysicsSpriteBox2D::createWithTexture(_spriteTexture, Rect(32 * idx, 32 * idy, 32, 32));
    parent->addChild(sprite);
    sprite->setB2Body(body);
    sprite->setPTMRatio(PTM_RATIO);
    sprite->setPosition(ax::Vec2(p.x, p.y));
}

void Box2DTest::update(float dt)
{
    // It is recommended that a fixed time step is used with Box2D for stability
    // of the simulation, however, we are using a variable time step here.
    // You need to make an informed choice, the following URL is useful
    // http://gafferongames.com/game-physics/fix-your-timestep/

    int velocityIterations = 8;
    int positionIterations = 1;

    // Instruct the world to perform a single step of simulation. It is
    // generally best to keep the time step and iterations fixed.
    world->Step(dt, velocityIterations, positionIterations);

    // Debug draw
    if (showDebugDraw)
    {
        drawBox2D->clear();
        world->DebugDraw();
    }
}

void Box2DTest::onTouchesEnded(const std::vector<Touch*>& touches, Event* event)
{
    // Add a new body/atlas sprite at the touched location

    for (auto& touch : touches)
    {
        if (!touch)
            break;

        auto location = touch->getLocation();

        addNewSpriteAtPosition(location);
    }
}