Here I write up the Alternate RotateAndZoomImage sub with more comments and test it out with demo:
Feature Sub:
So important to understand Rotozoom, so really cool to be able to derive it on your own with a little guidance from Galleon's example.
EDIT to fix spelling
Feature Sub:
Code: (Select All)
Sub RotateAndZoomImage (aboutX, aboutY, Img&, xyScale, radianRot, dest&)
Dim px(1 To 4), py(1 To 4), rotx(1 To 4), roty(1 To 4)
' aboutX, aboutY is the centerPoint for the destination image
' Img& is image handle from drawn _newImage or _LoadImage
' xyScale is multiplier to shrink or grow image projection from Map Triangle
' RadianRot is the angle in radians to turn the image from 0 rotation clockwise when positive
' dest& is where you want the projected image drawn 0 is the screen
' This part sets up our Destination points for _MapTriangle, 4 points around a Center X, Y point
w = _Width(Img&) / 2 ' these are 1/2 widths and heights for faster calc of destination coordinates
h = _Height(Img&) / 2
' the 4 points are the central point +- half the width and or height
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
' the "radius" of 4 points from the center will be same for square or rectangle image
radius = _Hypot(py(1) - aboutY, px(1) - aboutX) ' radius is all the same
' the 4 projection points needs to be rotated
For i = 1 To 4
angle = _Atan2(py(i) - aboutY, px(i) - aboutX) ' the angle the point is before rotation
rotA = angle + radianRot ' add the rotation to angle
'rotated x, y point
rotx(i) = aboutX + xyScale * radius * Cos(rotA)
roty(i) = aboutY + xyScale * radius * Sin(rotA)
Next
' this w, h concerns the Triangle coordinates for the Source _MapTriangle points
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 SubCode: (Select All)
_Title "Test Alternate RotoZoom Derived From Point Rotation" ' b+ 2022-09-09
Screen _NewImage(600, 350, 32)
' from demo code for Lander
' =========================================== make background snapshot
Color , _RGB32(30, 30, 60)
snapBack& = _NewImage(_Width, _Height, 32)
Cls
DrawTerrain 100, 25, &HFF332211
DrawTerrain 150, 20, &HFF443322
DrawTerrain 200, 15, &HFF554433
DrawTerrain 250, 10, &HFF665544
DrawTerrain 300, 5, &HFF776655
_PutImage , 0, snapBack&
' ========================================== make a spaceship sprite
ship& = _NewImage(61, 31, 32) ' ship is 60 x 30 drawn in top left hand corner
' need black backgrounf for ship
Color , &HFF000000 '= black background
Cls
drawShip 30, 15, &HFF00FF88
_PutImage , 0, ship&, (0, 0)-(61, 31) ' <<<< upper left corner of screen!!!
_ClearColor &HFF000000, ship& ' <<< make the background black of ship transparent
' ============================================= now for test of Alternate RotoZoom
sx = 0 ' from left edge to right and back
dx = 5 ' 270 / 5 = 54 loops to go from start to mid screen with max tilt there at pi(.25)
tilt = 0
dt = _Pi(.25 / 54)
scale = 1
ds = 1 / 54 ' want to double scale at 54 loops
Do
_PutImage , snapBack&, 0 ' back to screen
'rotozoom workes from image center, add 30 for middle of ship 15 add to y keeps ship lower
RotateAndZoomImage sx + 30, 175 + 15, ship&, scale, tilt, 0 ' ship to screen at destination x, y
' update x, scale and tilt
sx = sx + dx
If sx > _Width - 60 Then
sx = _Width - 60: dx = -dx
scale = 1: tilt = 0
ElseIf sx < 0 Then
sx = 0: dx = -dx
scale = 1: tilt = 0
ElseIf Abs(sx - 270) < .01 And dx > 0 Then
dt = -dt: ds = -ds
ElseIf Abs(sx - 270) < .01 And dx < 0 Then
dt = -dt: ds = -ds
End If
scale = scale + ds
tilt = tilt + dt
Locate 1, 1
Print "Press escape to quit..."
_Display 'no flicker
_Limit 20 ' max 20 loops a second
Loop Until _KeyDown(27)
Sub drawShip (x, y, colr As _Unsigned Long) 'shipType collisions same as circle x, y radius = 30
Static ls
Dim light As Long, r As Long, g As Long, b As Long
r = _Red32(colr): g = _Green32(colr): b = _Blue32(colr)
fellipse x, y, 6, 15, _RGB32(r, g - 120, b - 100)
fellipse x, y, 18, 11, _RGB32(r, g - 60, b - 50)
fellipse x, y, 30, 7, _RGB32(r, g, b)
For light = 0 To 5
fcirc x - 30 + 11 * light + ls, y, 1, _RGB32(ls * 50, ls * 50, ls * 50)
Next
ls = ls + 1
If ls > 5 Then ls = 0
End Sub
' ======== helper subs for drawShip that you can use for other things specially fcirc = fill_circle x, y, radius, color
Sub fellipse (CX As Long, CY As Long, xr As Long, yr As Long, C As _Unsigned Long)
If xr = 0 Or yr = 0 Then Exit Sub
Dim h2 As _Integer64, w2 As _Integer64, h2w2 As _Integer64
Dim x As Long, y As Long
w2 = xr * xr: h2 = yr * yr: h2w2 = h2 * w2
Line (CX - xr, CY)-(CX + xr, CY), C, BF
Do While y < yr
y = y + 1
x = Sqr((h2w2 - y * y * w2) \ h2)
Line (CX - x, CY + y)-(CX + x, CY + y), C, BF
Line (CX - x, CY - y)-(CX + x, CY - y), C, BF
Loop
End Sub
Sub fcirc (x As Long, y As Long, R As Long, C As _Unsigned Long) 'vince version fill circle x, y, radius, color
Dim x0 As Long, y0 As Long, e As Long
x0 = R: y0 = 0: e = 0
Do While y0 < x0
If e <= 0 Then
y0 = y0 + 1
Line (x - x0, y + y0)-(x + x0, y + y0), C, BF
Line (x - x0, y - y0)-(x + x0, y - y0), C, BF
e = e + 2 * y0
Else
Line (x - y0, y - x0)-(x + y0, y - x0), C, BF
Line (x - y0, y + x0)-(x + y0, y + x0), C, BF
x0 = x0 - 1: e = e - 2 * x0
End If
Loop
Line (x - R, y)-(x + R, y), C, BF
End Sub
Sub DrawTerrain (h, modN, c As _Unsigned Long) ' modN for ruggedness the higher the less smooth
For x = 0 To _Width
If x Mod modN = 0 Then ' adjust mod number for ruggedness the higher the number the more jagged
If h < 350 - modN And h > 50 + modN Then
dy = Rnd * 20 - 10
ElseIf h >= 350 - modN Then
dy = Rnd * -10
ElseIf h <= 50 + modN Then
dy = Rnd * 10
End If
End If
h = h + .1 * dy
Line (x, _Height)-(x, h), c
Next
End Sub
Sub RotateAndZoomImage (aboutX, aboutY, Img&, xyScale, radianRot, dest&)
Dim px(1 To 4), py(1 To 4), rotx(1 To 4), roty(1 To 4)
' aboutX, aboutY is the centerPoint for the destination image
' Img& is image handle from drawn _newImage or _LoadImage
' xyScale is multiplier to shrink or grow image projection from Map Triangle
' RadianRot is the angle in radians to turn the image from 0 rotation clockwise when positive
' dest& is where you want the projected image drawn 0 is the screen
' This part sets up our Destination points for _MapTriangle, 4 points around a Center X, Y point
w = _Width(Img&) / 2 ' these are 1/2 widths and heights for faster calc of destination coordinates
h = _Height(Img&) / 2
' the 4 points are the central point +- half the width and or height
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
' the "radius" of 4 points from the center will be same for square or rectangle image
radius = _Hypot(py(1) - aboutY, px(1) - aboutX) ' radius is all the same
' the 4 projection points needs to be rotated
For i = 1 To 4
angle = _Atan2(py(i) - aboutY, px(i) - aboutX) ' the angle the point is before rotation
rotA = angle + radianRot ' add the rotation to angle
'rotated x, y point
rotx(i) = aboutX + xyScale * radius * Cos(rotA)
roty(i) = aboutY + xyScale * radius * Sin(rotA)
Next
' this w, h concerns the Triangle coordinates for the Source _MapTriangle Points
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 SubSo important to understand Rotozoom, so really cool to be able to derive it on your own with a little guidance from Galleon's example.
EDIT to fix spelling
b = b + ...