Real Time 2D Rotating

Is it possible to quickly rotate images in B3D?

This was taken from game programming for teens

Graphics 800,600
;Set up AutoMidHandle and BackBuffer()
AutoMidHadle True
Setbuffer backbuffer()

;Images
;Load yourimage that will be rotated
yourimage=loadimage("yourimage.bmp")

;CONSTANTS
;How many rotations do you want total
Const rotations = 16

;Create the rotation array
Dim imagearray(rotations)

;For all of the rotations you want,  copy the spaceship image and routate it the correct amount of degrees
For frame=0 to rotations-1
        imagearray(frame) = copyimage(yourimage)
        rotateimage imagearray(frame), frame*360/rotations
Next

Print "Press Left to rotate conter-clockwise and right to rotate clockwise,"
print "Press Esc to exit."

;Begin at frame 0 (facing upward)
frame=0

;MAIN LOOP
while not keydown(1)

;Clear the screen
cls

;Rotate the ship left if use presses left
If Keydown(203)

;Decrement frame by 1 (thus rotating it left
         frame=frame-1

;If the frame count is less the 0,put it back at the max value of the array
         if frame<0
                     frame=rotations - 1
         endif
;Rotate the ship right if user presses right
elseif keydown(205)

;Increment frame by 1 (thus rotating it right)
          frame=frame+1

;If the frame gets to big, set it to the first frame (0)
          If frame >= rotations
                      frame=0
          endif

endif

drawimage imagearray(frame),400,300


flip

;Wait for a while
Delay 50
Wend

-

Since your using b3d, maybe you could use a texture instead:

Graphics3D 800, 600, 0, 2
SetBuffer BackBuffer()

tex = CreateTexture(256, 256, 1, 8)

Rect 0, 0, 256, 256

For i = 0 To 20

	x1 = Rand(256)
	y1 = Rand(256)	
	x2 = Rand(256)
	y2 = Rand(256)
	Color 0, 0, Rand($FFFFFF)
	Line x1, y1, x2, y2
	
Next

CopyRect 0, 0, 256, 256, 0, 0, BackBuffer(), TextureBuffer(tex)

camera = CreateCamera()
MoveEntity camera, 0, 0, -2

cube = CreateCube()
ScaleEntity cube, 1, 1, 0.01
EntityTexture cube, tex

Repeat

	RotateEntity cube, 0, 0, MilliSecs() / 10.0
	
	RenderWorld()
	Flip 0
	
Until KeyHit(1)

End

Thanks guys, I'll try your ideas...

@Cyberspy
I've been testing your method and I got it to work without functions in my code.

@Everyone
How can I define arrays and constants as global so I can use them in functions?

I think you can use Constants in functions just like globals, not sure about arrays though.

Okay, thanks for the tip. I'm almost positive that arrays don't work in functions (unless they're somehow defined as global).

In my program, the compiler ignores rotating the image--but still draws it in the default position.

Arrays are global (see below). You can't actually have local arrays in b3d.

Dim array(9)

For i=0 To 9
	array(i)=i
Next

printArray(0,9)
WaitKey

Function printArray(iFrom,iTo)
Print array(iFrom)
iFrom=iFrom+1
If iFrom<(iTo+1) Then printArray(iFrom,iTo)
End Function

B3D does actually support local arrays. Just use square brackets, a la array[10]. However, this type of array can only be one dimensional.

Man, I'm glad you posted - I'd gotten it into my head that 'blitz arrays' could only be used in types. RTFM, Sledge!

Okay, I'll report back if I have more problems.

Heh - to be fair, I dont think blitz arrays are even in the manual. :) I also forgot to mention you need to use the Local keyword when defining blitz arrays, so it should actually be 'Local array[10]'. :)