I need some help because, I am very good useing math.
The user draws a rectangle with the mouse.
SO I have (X1,Y1) and (X2,Y2)
(X1,Y1) are the top left coordinates and
(X2,Y2) are the bottom right coordinates.
I have computed the slope and got the angle.
The rectangle drawn is at (X1,Y1,0)-(X2,Y2,0) but if want to display or to rotate along an axis I need the Z coordinate.
static int Create3DObject(HWND __hWnd,int __iX_First,int __iY_First,int __iX_Last,int __iY_Last)
{
int _iX1, _iY1, _iX2, _iY2 ;
int _iWidth, _iHeight ;
int _iPrevIndex ;
double _dDistance, _dSlope, _dAngle ;
double _dDelta_X, _dDelta_Y ;
LPOBJECT3D _lpFirstObject, _lpTmpObject, _lpObject ;
if((__iX_First == __iX_Last) && (__iY_First == __iY_Last))
{
Error("Cannot create an object if the distance between points is equal to 0") ;
return (FALSE) ;
}
_iX1 = __iX_First ;
_iY1 = __iY_First ;
_iX2 = __iX_Last ;
_iY2 = __iY_Last ;
_iWidth = abs(_iX2 - _iX1) ;
_iHeight = abs(_iY2 - _iY1) ;
if(_iHeight == 0)
return (Error("Cannot create an object if its height is equal to 0")) ;
_dDistance = sqrt(pow((double) _iWidth,2) + pow((double) _iHeight,2)) ;
if(_dDistance == 0.00)
return (Error("Cannot create an object if the distance between points is equal to 0")) ;
_dDelta_Y = ((double) _iY2) - ((double) _iY1) ;
_dDelta_X = ((double) _iX2) - ((double) _iX1) ;
_dSlope = _dDelta_Y / _dDelta_X ;
_dAngle = VANISH_RAD_TO_DEG * atan2(_dDelta_Y,_dDelta_X) ;
_lpFirstObject = (LPOBJECT3D) GetWindowLongPtr(__hWnd,GWLP_USERDATA) ;
if(_lpFirstObject == NULL)
{
_lpObject = (LPOBJECT3D) malloc(sizeof(OBJECT3D)) ;
if(_lpObject == NULL)
{
Error("Not enough memory for allocating a new object") ;
return (FALSE) ;
}
_lpObject->Index = 1 ;
_lpObject->Liste.lpPrev = NULL ;
_lpObject->Liste.lpNext = NULL ;
SetWindowLongPtr(__hWnd,GWLP_USERDATA,(LONG_PTR) _lpObject) ;
}
else
{
_iPrevIndex = 0 ;
_lpTmpObject = _lpFirstObject ;
while(_lpTmpObject->Liste.lpNext != NULL)
{
if(_iPrevIndex < _lpTmpObject->Index)
_iPrevIndex = _lpTmpObject->Index ;
_lpTmpObject = (LPOBJECT3D) _lpTmpObject->Liste.lpNext ;
}
_lpObject = (LPOBJECT3D) malloc(sizeof(OBJECT3D)) ;
if(_lpObject == NULL)
{
Error("Not enough memory for allocating a new object") ;
return (FALSE) ;
}
_lpTmpObject->Liste.lpNext = _lpObject ;
_lpObject->Liste.lpPrev = _lpTmpObject ;
_lpObject->Liste.lpNext = NULL ;
_lpObject->Index = _iPrevIndex + 1 ;
}
_lpObject->ColorBrush = -1 ; // NULL BRUSH
_lpObject->ColorPen = 0x000000FF ;
// z = sqrt(x² + y² - 2 * x * y * cos(γ)) ?
_lpObject->Coordonnees3D.Distance = _dDistance ;
_lpObject->Coordonnees3D.Slope = _dSlope ;
_lpObject->Coordonnees3D.Angle = _dAngle ;
_lpObject->Coordonnees3D.DeltaX = _dDelta_X ;
_lpObject->Coordonnees3D.DeltaY = _dDelta_Y ;
_lpObject->Coordonnees3D.Left.x = _iX1 ;
_lpObject->Coordonnees3D.Left.y = _iY1 ;
_lpObject->Coordonnees3D.Left.z = sqrt(pow((double) _iX1,2) + pow((double) _iY1,2) - (2 * (double) _iX1 * (double) _iY1 * cos(_dAngle))) ;
_lpObject->Coordonnees3D.Right.x = _iX2 ;
_lpObject->Coordonnees3D.Right.y = _iY2 ;
_lpObject->Coordonnees3D.Right.z = sqrt(pow((double) _iX2,2) + pow((double) _iY2,2) - (2 * (double) _iX2 * (double) _iY2 * cos(_dAngle))) ;
_lpObject->Coordonnees3D.Rectangle.x = _iX1 ;
_lpObject->Coordonnees3D.Rectangle.y = _iY1 ;
_lpObject->Coordonnees3D.Rectangle.z = sqrt(pow((double) _iX1,2) + pow((double) _iY1,2) - (2 * (double) _iX1 * (double) _iY1 * cos(_dAngle))) ;
_lpObject->Coordonnees3D.Rectangle.width = _iWidth ;
_lpObject->Coordonnees3D.Rectangle.height = _iHeight ;
_lpObject->Coordonnees3D.Rectangle.Depth = abs(_iX1 - _lpObject->Coordonnees3D.Rectangle.z) ;
lpCurrentObject = _lpObject ;
return (TRUE) ;
}
z = sqrt(x² + y² - 2 * x * y * cos(γ))
This is how I compute the Z.
It is a formula I found somewhere on the internet but I don't know it this is good.
Some help would be welcome.
Thank You / Merci
