What am I missing here?

[bplus]

OK fixed.

We were just 2 steps away from Classic RotoZoom. Incorporate the RotatePoint code into the RotateAndZoomImage sub and add a scale for the Destination points to grow or shrink the radius:

Code: (Select All)

_Title "Rotate and Zoom from Point perspective" 'b+ 2022-09-08

Screen _NewImage(800, 600, 32)

rotateCenterX = _Width / 2
rotateCenterY = _Height / 2

' OK make a rectangle image  50x100 and rotate it around the center of the screen in 30 degree increments
Line (0, 0)-(49, 99), &HFFFFFF00, BF
rect& = _NewImage(50, 100, 32)
_PutImage , 0, rect&, (0, 0)-(49, 99)
scale = .5
For a = 0 To _Pi(2) - .001 Step _Pi(1 / 12)
    Cls
    RotateAndZoomImage rotateCenterX, rotateCenterY, rect&, scale, a, 0
    Print "Rotated"; _R2D(a); "  scaled at:"; scale
    scale = scale + .1
    Sleep
Next

Sub RotateAndZoomImage (aboutX As Long, aboutY As Long, Img&, xyScale, radianRot, dest&)
    Dim px(1 To 4), py(1 To 4), rotx(1 To 4), roty(1 To 4)
    w = _Width(Img&) / 2 ' these are 1/2 widths and heights for faster calc of destination coordinates
    h = _Height(Img&) / 2
    px(1) = aboutX - w: py(1) = aboutY - h
    px(2) = aboutX - w: py(2) = aboutY + h
    px(3) = aboutX + w: py(3) = aboutY + h
    px(4) = aboutX + w: py(4) = aboutY - h
    radius = _Hypot(py(1) - aboutY, px(1) - aboutX) ' radius is all the same
    For i = 1 To 4
        angle = _Atan2(py(i) - aboutY, px(i) - aboutX)
        rotA = angle + radianRot
        'rotated x, y point
        rotx(i) = aboutX + xyScale * radius * Cos(rotA)
        roty(i) = aboutY + xyScale * radius * Sin(rotA)
    Next
    w = _Width(Img&) - 1 'for source coordinates
    h = _Height(Img&) - 1
    _MapTriangle (0, 0)-(0, h)-(w, h), Img& To(rotx(1), roty(1))-(rotx(2), roty(2))-(rotx(3), roty(3)), dest&
    _MapTriangle (0, 0)-(w, 0)-(w, h), Img& To(rotx(1), roty(1))-(rotx(4), roty(4))-(rotx(3), roty(3)), dest&
End Sub