Any two points is known, as the long axis of the ellipse two endpoints, and short axis length, survival into elliptical code

Is first point two times as long axis, automatically generate a perpendicular bisector, then define a short axis endpoint, thus know short axial length,

Note is arbitrary Angle either horizontal or vertical,

I this kind of code but debugging of ellipse is not too much, always partial

 Private Sub drawC (objName As Object, As point p1, p2 As point, As Single b) 
'input x1, x2, y1, y2, b long axis line endpoint, length of short half axis 
Dim x1 As Single 
Dim x2 As Single 
Dim y1 As Single 
Dim y2 As Single 
Dim x0 As Single center 
 'Dim y0 As Single center 
 'Dim As a Single 'long axis half 
Dim k1 As Single slope 
 'Dim theta Angle As Single '
Dim temp As point 


X1=p1. X 
X2=p2. X 
Y1=p1. Y 
Y2=p2. Y 

X0=(x1 + x2)/2 'anchor point 
Y0=(y1 and y2)/2 


If x1 x2=Then 'theta equals PI/2 or 3 PI/2 
A=(Abs (y1, y2))/2 
X0=x1 
Y0=0.5 * (y1 and y2) 
For I=1 To 360 Step 1 
ObjName. Circle (x0, y0), a, QBColor (12), the Arc * (I - 1), the Arc * 1, (a/b) 
Next I 
The Exit Sub 
End the If 

K1=(y2 - y1)/(x2 - x1) 
Theta=180 * Atn ((y2 - y1)/(x2 - x1))/3.1415926 
A=Sqr ((x2 - x1) ^ 2 + (y2 - y1) ^ 2)/2 
N=100 'in the period of 2 PI score 
Dt=2 * 3.1415926/n 
T=0 
If Tan (theta) & gt; Then '0 0 & lt; Theta & lt; PI/2 or piCurrentX=0.5 * (x1 + x2) + b * k1/Sqr (k1 ^ 2 + 1) 
CurrentY=0.5 * (y1 and y2) + b/Sqr (k1 ^ 2 + 1) 
ElseIf Tan (theta) & lt; 0 Then 'PI/2 & lt; Theta & lt; PI or 3 PI/2 & lt; Theta & lt; 2 PI 
CurrentX=0.5 * (x1 + x2) - b * k1/Sqr (k1 ^ 2 + 1) 
CurrentY=0.5 * (y1 and y2) - b/Sqr (k1 ^ 2 + 1) 
Else '=Y1 Y2, theta equals zero or PI PI/2 
CurrentX=0.5 * (x1 + x2) 
CurrentY=0.5 * (y1 and y2) 
End the If 
ObjName. PSet (CurrentX, CurrentY), vbRed 
'objName. PSet (x0, y0), vbYallow 
For j=0 To n 
Temp. X=x0 + a * Cos (theta) * Sin (t) - b * Sin (theta) * Cos (t) 
Temp.=y0 y + a * Sin (theta) * Sin (t) - b * Cos (theta) * Cos (t) 
ObjName. Line - (temp. X, temp., y), QBColor (12) 
T=t + dt 
Next j 

End Sub 

CodePudding user response:

Find a function, and the Internet and a are not right, also not the same as two math is not good, please to see

 Private Sub drawC2 (objName As Object, As Single x, y, As Single As a Single, As Single b, c As Single, petColor As OLE_COLOR, d As an Integer) 
Dim t As Double 
Dim tempx As Single 
Dim tempy As Single 
Dim x1 As Single 
Dim y1 As Single 
Dim c1 As Single 
ObjName. DrawWidth=d 
C1=- Atn 45 * (1)/c 
For t=3.1415926535 To 3.1415926535 Step 0.003 
Tempx=Cos (t) * a 
Tempy=Sin (t) * b 
X1=x + tempx * Cos (c1) - tempy * Sin (c1) 
Y1=y + tempx * Sin (c1) + tempy * Cos (c1) 
ObjName. PSet (x1, y1), petColor 
Next t 

End Sub 

CodePudding user response:

1)
Draw the ellipse, then the translation, rotation, elliptical image
2)
Write elliptic equations, translation, rotation, new elliptic equation is obtained, and then make your own interpolation algorithm, draw the ellipse,

CodePudding user response:

Private Declare the Function the Ellipse Lib "gdi32" (ByVal HDC As Long, ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long


Do you know the coordinates of the long axis, also know the length of the short axis, should it is easy to determine the draw area at the upper left of the rectangle and the coordinates of the lower right corner, know after, can use: Elipse plotted,

CodePudding user response:

Simple example, the Picture1 with elliptical

 
 'define several constants and functionPublic Const r_pi=3.14159265758979 ', 3.14159265358979323846 
Public Const d_pi=180 


As Function d2r (a Double) As a Double 
D2r=a * r_pi/d_pi 
End the Function 

As Function r2d (a Double) As a Double 
R2d=a * d_pi/r_pi 
End the Function 

As Function SinD (a Double) As a Double 
SinD=Sin (d2r) (a) 
End the Function 

As Function CosD (a Double) As a Double 
CosD=Cos (d2r) (a) 
End the Function 

'draw ellipse 
Private Sub Command1_Click () 
Dim x As Single, y As Single 
Dim x1 As Single, y1 As Single 
Dim As a Single 
Dim As Double b 
Dim alpha As Double 


'
'the parametric equation of ellipse 
'x=a cosine (alpha) 
'y=b sin (alpha) 
'
'
Dim beta As a Double 

Dim theta As Long 
Dim sc As Long 
Sc=8 
For theta=0 To 360 * sc 
A=1400 
B=1200 
Beta=60 

X0=1500 
Y0=2400 

Alpha=theta * 1 # 


X1=a + a * SinD (alpha/sc) 
Y1=b + b * CosD (alpha/sc) 

X=x0 + x1 x SinD (beta) + y1 * CosD (beta) 
Y=y0 + x1 * CosD (beta) - y1 * SinD (beta) 

Picture1. PSet (x, y), RGB (200, 100, 100) 

Next is 

End Sub 

CodePudding user response:

3/f,

 Private Declare the Function the Ellipse Lib "gdi32" (ByVal HDC As Long, ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long 
Private Sub Command1_Click () 
The Ellipse Picture1. HDC, 500, 0, 0, 300 
End Sub 

CodePudding user response:

Call API draw ellipse axle not on the axis direction, the need to do the following processing
1) coordinate translation and rotation this must master
2) the Ellipse drawing
3) to use the path keep drawing parameters, in order to rotate coordinates
4) after the rotation of the path charted
Want to use the following API

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