public AABB(Transform transform)
{
this.transform = transform;
Mesh mesh = transform.GetComponent <MeshFilter>().sharedMesh;
originMin = originMax = mesh.vertices[0];
for (int i = 1; i < mesh.vertices.Length; i++)
{
for (int j = 0; j < 3; j++)
{
if (mesh.vertices[i][j] < originMin[j])
{
originMin[j] = mesh.vertices[i][j];
}
if (mesh.vertices[i][j] > originMax[j])
{
originMax[j] = mesh.vertices[i][j];
}
}
}
transformMin = originMin;
transformMax = originMax;
matrix = Matrix4x4.identity;
mode = AABBStructureMode.None;
}
public void UpdateAABB(AABBStructureMode mode)
{
Matrix4x4 m = transform.localToWorldMatrix;
//只发生平移的话不需要重新计算包围盒，直接加上偏移量即可
if (MathUtil.IsOnlyContainTranslation(matrix, m) && this.mode == mode)
{
Vector3 translation = MathUtil.GetTranslation(matrix, m);
transformMin += translation;
transformMax += translation;
}
else
{
this.mode = mode;
//加速模式：只对max和min进行变换，不保证计算得到的包围盒是紧凑的
if (mode == AABBStructureMode.Accelerate)
{
Vector3 translate = new Vector3(m.m03, m.m13, m.m23);
transformMin = translate;
transformMax = translate;
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
float e = m[j, i] * originMin[i];
float f = m[j, i] * originMax[i];
if (e < f)
{
transformMin[j] += e;
transformMax[j] += f;
}
else
{
transformMin[j] += f;
transformMax[j] += e;
}
}
}
}
//紧凑模式：对所有顶点进行变换，计算得到的包围盒是紧凑的
else if (mode == AABBStructureMode.Compact)
{
Mesh mesh = transform.GetComponent <MeshFilter>().sharedMesh;
List <Vector3> vertices = Util.GetNoRepeatVertices(mesh);
transformMin = transformMax = m * MathUtil.Vector4(vertices[0], 1);
for (int i = 1; i < vertices.Count; i++)
{
for (int j = 0; j < 3; j++)
{
Vector3 tmp = m * MathUtil.Vector4(vertices[i], 1);
if (tmp[j] < transformMin[j])
{
transformMin[j] = tmp[j];
}
if (tmp[j] > transformMax[j])
{
transformMax[j] = tmp[j];
}
}
}
}
}
matrix = m;
}
