Get the bounding box of a jsr 184 mesh

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Created: ed_welch (03 Nov 2007)

Last edited: hamishwillee (18 Jul 2012)

Something I wrote a long time ago, but comes in quite handy. This function returns the bounding box on any mesh

// Gets the bounder box of any mesh
// returns an array for the min and max of each axis
// extreme[0].min = x axis min value, 
// extreme[1].min = y axis min value, etc...
public MinMax[] GetExtremes(Mesh mesh)
{
	MinMax[] extreme = new MinMax[3];
	VertexBuffer vertexBuffer = mesh.getVertexBuffer();
	float[] scaleBias = new float[4];
	VertexArray postionArray = vertexBuffer.getPositions(scaleBias);
 
	float[] out = new float[vertexBuffer.getVertexCount() * 4];
	Transform trans = new Transform();
 
	trans.postTranslate(scaleBias[1], scaleBias[2], scaleBias[3]);
	trans.postScale(scaleBias[0], scaleBias[0], scaleBias[0]);
	trans.transform(postionArray, out, true);
	int n;
	int axis;
	for (axis = 0; axis < 3; axis++)
	{
		extreme[axis] = new MinMax();
		extreme[axis].max = out[axis];
		extreme[axis].min = out[axis];
	}
	for (n = 4; n < out.length / 4; n++)
	{
		for (axis = 0; axis < 3; axis++)
		{
			if (extreme[axis].max < out[n * 4 + axis])
			{
				extreme[axis].max = out[n * 4 + axis];
			}
			if (extreme[axis].min > out[n * 4 + axis])
			{
				extreme[axis].min = out[n * 4 + axis];
			}
		}
	}
	mesh.getScale(scaleBias); // reuse scaleBias
	for (axis = 0; axis < 3; axis++)
	{
		extreme[axis].max *= scaleBias[axis];
		extreme[axis].min *= scaleBias[axis];
	}
	return extreme;
}
 
 
public class MinMax
{
    float min = 0f, max = 0f;
    MinMax() {}
}