/*
 * C# / XNA  port of Bullet (c) 2011 Mark Neale <[email protected]>
 *
 * Bullet Continuous Collision Detection and Physics Library
 * Copyright (c) 2003-2008 Erwin Coumans  http://www.bulletphysics.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.
 */
// Adapted from BulletXNA 73b2e1b9: namespace isolation, no XNA rendering, one type per file.
#nullable disable
#pragma warning disable CS1591, CS0168, CS0219, CS0414, CS0660, CS0661, CS0659, CS0693, CS8981, CS0108, CS0114
using System;
using System.Diagnostics;
using HumanoidRetargeter.Core.Formats.Mmd.Bullet.LinearMath;

namespace HumanoidRetargeter.Core.Formats.Mmd.Bullet.BulletCollision;

internal class CenterCallback : IInternalTriangleIndexCallback
{
	public CenterCallback()
	{
		first = true;
		reference = new IndexedVector3();
		sum = new IndexedVector3();
		volume = 0f;
	}

	public virtual bool graphics()
	{
		return false;
	}

	public virtual void InternalProcessTriangleIndex(IndexedVector3[] triangle, int partId, int triangleIndex)
	{
		if (first)
		{
			reference = triangle[0];
			first = false;
		}
		else
		{
			IndexedVector3 a = triangle[0] - reference;
			IndexedVector3 b = triangle[1] - reference;
			IndexedVector3 c = triangle[2] - reference;
			float vol = Math.Abs(a.Triple(ref b, ref c));
			sum += (.25f * vol) * ((triangle[0] + triangle[1] + triangle[2] + reference));
			volume += vol;
		}
	}

	public IndexedVector3 GetCenter()
	{
		return (volume > 0) ? sum / volume : reference;
	}

	public float GetVolume()
	{
		return volume * (1f / 6f);
	}

	public void Cleanup()
	{
	}

	bool first;
	IndexedVector3 reference;
	IndexedVector3 sum;
	float volume;
}