// SPDX-FileCopyrightText: 2025 Erin Catto

// SPDX-FileCopyrightText: 2025 Ikpil Choi(ikpil@naver.com)

// SPDX-License-Identifier: MIT

using System.Collections.Generic;

using static Box2D.NET.B2Types;

using static Box2D.NET.B2Bodies;

using static Box2D.NET.B2Shapes;

using static Box2D.NET.B2Worlds;

using static Box2D.NET.Samples.Graphics.Draws;

namespace Box2D.NET.Samples.Samples.Stackings;

// A simple circle stack that also shows how to collect hit events

public class CircleStack : Sample

{

private static readonly int SampleCircleStack = SampleFactory.Shared.RegisterSample("Stacking", "Circle Stack", Create);

private List<Event> m_events = new List<Event>();

private static Sample Create(SampleContext context)

{

return new CircleStack(context);

}

public struct Event

{

public int indexA, indexB;

public Event(int indexA, int indexB)

{

this.indexA = indexA;

this.indexB = indexB;

}

};

public CircleStack(SampleContext context) : base(context)

{

if (m_context.restart == false)

{

m_camera.center = new B2Vec2(0.0f, 5.0f);

m_camera.zoom = 6.0f;

}

int shapeIndex = 0;

{

B2BodyDef bodyDef = b2DefaultBodyDef();

B2BodyId groundId = b2CreateBody(m_worldId, bodyDef);

B2ShapeDef shapeDef = b2DefaultShapeDef();

shapeDef.userData = B2UserData.Signed(shapeIndex);

shapeIndex += 1;

B2Segment segment = new B2Segment(new B2Vec2(-10.0f, 0.0f), new B2Vec2(10.0f, 0.0f));

b2CreateSegmentShape(groundId, shapeDef, segment);

}

b2World_SetGravity(m_worldId, new B2Vec2(0.0f, -20.0f));

b2World_SetContactTuning(m_worldId, 0.25f * 360.0f, 10.0f, 3.0f);

{

B2BodyDef bodyDef = b2DefaultBodyDef();

bodyDef.type = B2BodyType.b2_dynamicBody;

B2Circle circle = new B2Circle();

circle.radius = 0.5f;

B2ShapeDef shapeDef = b2DefaultShapeDef();

shapeDef.enableHitEvents = true;

//shapeDef.rollingResistance = 0.2f;

shapeDef.material.friction = 0.0f;

shapeDef.material.restitution = 0.8f;

float y = 0.75f;

for (int i = 0; i < 4; ++i)

{

bodyDef.position.Y = y;

B2BodyId bodyId = b2CreateBody(m_worldId, bodyDef);

shapeDef.userData = B2UserData.Signed(shapeIndex);

shapeDef.density = 1.0f + 4.0f * i;

shapeIndex += 1;

b2CreateCircleShape(bodyId, shapeDef, circle);

y += 1.25f;

}

}

}

public override void Draw()

{

base.Draw();

B2ContactEvents events = b2World_GetContactEvents(m_worldId);

for (int i = 0; i < events.hitCount; ++i)

{

ref B2ContactHitEvent @event = ref events.hitEvents[i];

var userDataA = b2Shape_GetUserData(@event.shapeIdA);

var userDataB = b2Shape_GetUserData(@event.shapeIdB);

int indexA = (int)userDataA.GetSigned(-1);

int indexB = (int)userDataB.GetSigned(-1);

DrawPoint(m_draw, @event.point, 10.0f, B2HexColor.b2_colorWhite);

m_events.Add(new Event(indexA, indexB));

}

int eventCount = m_events.Count;

for (int i = 0; i < eventCount; ++i)

{

DrawScreenTextLine($"{m_events[i].indexA}, {m_events[i].indexB}");

}

}

}