private void Update()
{
if (Input.GetMouseButtonDown(0))
{
var pos = _camera.ScreenPointToRay(Input.mousePosition).origin;
_selectedIdx = FindOverlappedParticle(pos);
}
if (_selectedIdx >= 0)
{
var m = new Vector2(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical")) * Time.deltaTime * _moveFactor;
var pos = _target.GetParticlePosition(_selectedIdx);
pos += m;
_target.SetParticlePosition(_selectedIdx, pos);
}
}
/// <summary>
/// 指定した座標に最も近いパーティクルの番号を取得する
/// </summary>
/// <param name="position"></param>
/// <returns></returns>
int FindOverlappedParticle(Vector2 position)
{
if (!_target && !_target.IsReady())
{
return(-1);
}
int minIdx = -1;
float minSqrLength = _pickRadius * _pickRadius;
for (var i = 0; i < _target.GetParticleCount(); ++i)
{
var sqrLength = (_target.GetParticlePosition(i) - position).sqrMagnitude;
if (sqrLength < minSqrLength)
{
minIdx = i;
minSqrLength = sqrLength;
}
}
return(minIdx);
}