anki-3d-engine/ThirdParty/Bullet/Extras/ConvexDecomposition/bestfitobb.cpp

#include "float_math.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <assert.h>

/*----------------------------------------------------------------------
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					www.physicstools.org
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		that the following conditions are met:

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		and the following disclaimer.

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		this list of conditions and the following disclaimer in the documentation
		and/or other materials provided with the distribution.

		Neither the name of the Open Dynamics Framework Group nor the names of its contributors may
		be used to endorse or promote products derived from this software without specific prior written permission.

		THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 'AS IS' AND ANY EXPRESS OR IMPLIED WARRANTIES,
		INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
		DISCLAIMED. IN NO EVENT SHALL THE INTEL OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
		EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
		LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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-----------------------------------------------------------------------*/

// http://codesuppository.blogspot.com
//
// mailto: [email protected]
//
// http://www.amillionpixels.us
//

#include "bestfitobb.h"
#include "float_math.h"

// computes the OBB for this set of points relative to this transform matrix.
void computeOBB(unsigned int vcount, const float *points, unsigned int pstride, float *sides, const float *matrix)
{
	const char *src = (const char *)points;

	float bmin[3] = {1e9, 1e9, 1e9};
	float bmax[3] = {-1e9, -1e9, -1e9};

	for (unsigned int i = 0; i < vcount; i++)
	{
		const float *p = (const float *)src;
		float t[3];

		fm_inverseRT(matrix, p, t);  // inverse rotate translate

		if (t[0] < bmin[0]) bmin[0] = t[0];
		if (t[1] < bmin[1]) bmin[1] = t[1];
		if (t[2] < bmin[2]) bmin[2] = t[2];

		if (t[0] > bmax[0]) bmax[0] = t[0];
		if (t[1] > bmax[1]) bmax[1] = t[1];
		if (t[2] > bmax[2]) bmax[2] = t[2];

		src += pstride;
	}

	sides[0] = bmax[0];
	sides[1] = bmax[1];
	sides[2] = bmax[2];

	if (fabsf(bmin[0]) > sides[0]) sides[0] = fabsf(bmin[0]);
	if (fabsf(bmin[1]) > sides[1]) sides[1] = fabsf(bmin[1]);
	if (fabsf(bmin[2]) > sides[2]) sides[2] = fabsf(bmin[2]);

	sides[0] *= 2.0f;
	sides[1] *= 2.0f;
	sides[2] *= 2.0f;
}

void computeBestFitOBB(unsigned int vcount, const float *points, unsigned int pstride, float *sides, float *matrix)
{
	float bmin[3];
	float bmax[3];

	fm_getAABB(vcount, points, pstride, bmin, bmax);

	float center[3];

	center[0] = (bmax[0] - bmin[0]) * 0.5f + bmin[0];
	center[1] = (bmax[1] - bmin[1]) * 0.5f + bmin[1];
	center[2] = (bmax[2] - bmin[2]) * 0.5f + bmin[2];

	float ax = 0;
	float ay = 0;
	float az = 0;

	float sweep = 45.0f;  // 180 degree sweep on all three axes.
	float steps = 8.0f;   // 16 steps on each axis.

	float bestVolume = 1e9;
	float angle[3] = {0.f, 0.f, 0.f};

	while (sweep >= 1)
	{
		bool found = false;

		float stepsize = sweep / steps;

		for (float x = ax - sweep; x <= ax + sweep; x += stepsize)
		{
			for (float y = ay - sweep; y <= ay + sweep; y += stepsize)
			{
				for (float z = az - sweep; z <= az + sweep; z += stepsize)
				{
					float pmatrix[16];

					fm_eulerMatrix(x * FM_DEG_TO_RAD, y * FM_DEG_TO_RAD, z * FM_DEG_TO_RAD, pmatrix);

					pmatrix[3 * 4 + 0] = center[0];
					pmatrix[3 * 4 + 1] = center[1];
					pmatrix[3 * 4 + 2] = center[2];

					float psides[3];

					computeOBB(vcount, points, pstride, psides, pmatrix);

					float volume = psides[0] * psides[1] * psides[2];  // the volume of the cube

					if (volume <= bestVolume)
					{
						bestVolume = volume;

						sides[0] = psides[0];
						sides[1] = psides[1];
						sides[2] = psides[2];

						angle[0] = ax;
						angle[1] = ay;
						angle[2] = az;

						memcpy(matrix, pmatrix, sizeof(float) * 16);
						found = true;  // yes, we found an improvement.
					}
				}
			}
		}

		if (found)
		{
			ax = angle[0];
			ay = angle[1];
			az = angle[2];

			sweep *= 0.5f;  // sweep 1/2 the distance as the last time.
		}
		else
		{
			break;  // no improvement, so just
		}
	}
}