画像の回転 - abwiki @ ウィキ (ActiveBasic非公式wiki)

'座標(sx,sy)を(cx,cy)を中心としてr[RAD]反時計回りに回転させ、結果を(dx,dy)に返す
Function PointRotation(sx As Double, sy As Double, cx As Double, cy As Double, ByRef dx As Double, ByRef dy As Double, r As Double) As Long
 	dx = (sx-cx) * Cos(r) - (sy-cy) * Sin(r) + cx 
	dy = cy-(sx-cx) * Sin(r) - (sy-cy) * Cos(r)
	dy = cy*2 -dy'yミラー
End Function

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