is there a way to rotate an image with directx?

i want to be able to spin an image what ever degree i enter
with only one image

Absolutely. Just use
D3DXMatrixRotationX(YourMatrix, AngleInRadians)
That will handle rotation around the x-axis; for the other axes, use D3DXMatrixRotationY or D3DXMatrixRotationZ.

There should be quite a few examples in this forum, if you need more details.

G'day!

If you're using DirectDraw then you're out of luck. I think some hardware supports 90 degree rotations, but arbitrary rotations are completely unsupported with DirectDraw.

Which means either doing it manually or (maybe) using GDI. If it's something you're doing a lot of, GDI will not be fast enough. Most games just store different orientations.

Doing it manually would probably require assembly to get it fast enough.

So my recommendation (assuming DirectDraw) is to use a paint program and pre-rotate your art.

Of course, if you're using D3D, then it's trivial.

Stay Casual,

Ken

Originally posted by DrunkenHyena
Which means either doing it manually or (maybe) using GDI. If it's something you're doing a lot of, GDI will not be fast enough. Most games just store different orientations. Doing it manually would probably require assembly to get it fast enough.

Hi.
I'd have to beg to differ with you DrukenHyena, I found some code a while ago which someone wrote and modified it to use DirectX, it's all written in VB, and it runs pretty fast.


Public Const pi As Double = 3.141592654
'--------Function RotateSurface-----
'RotateSurface , takes a surface to rotate, the surface to draw the rotation on, the angle to rotate on,
'the x and y destination to draw on, an optional transparency value
'and optionally it can return the width and height of the surface
Public Function RotateSurface(ByRef surfSource As DirectDrawSurface7, surfDestination As DirectDrawSurface7,_
lngAngle As Long, XDest As Long, Ydest As Long, Optional rgbTransparency As Long = -1, Optional ByRef Width As Long, _
Optional ByRef height As Long)
Dim ddsdOriginal As DDSURFACEDESC2, ddsdDestination As DDSURFACEDESC2
Dim iX As Long, iY As Long
Dim iXDest As Long, iYDest As Long
Dim rEmpty As RECT, rEmpty2 As RECT
Dim sngA As Single, SinA As Single, CosA As Single
Dim dblRMax As Long
Dim lngXO As Long, lngYO As Long
Dim lngColor As Long
Dim lWidth As Long, lHeight As Long

sngA = lngAngle * pi / 180
SinA = Sin(sngA)
CosA = Cos(sngA)

surfSource.GetSurfaceDesc ddsdOriginal
lWidth = ddsdOriginal.lWidth
lHeight = ddsdOriginal.lHeight
dblRMax = Sqr(lWidth ^ 2 + lHeight ^ 2)
surfSource.Lock rEmpty, ddsdOriginal, DDLOCK_WAIT, 0
surfDestination.GetSurfaceDesc ddsdDestination
surfDestination.Lock rEmpty2, ddsdDestination, DDLOCK_WAIT, 0

XDest = XDest + lWidth / 2
Ydest = Ydest + lHeight / 2
For iX = -dblRMax To dblRMax
For iY = -dblRMax To dblRMax
lngXO = lWidth / 2 - (iX * CosA + iY * SinA)
lngYO = lHeight / 2 - (iX * SinA - iY * CosA)
If lngXO >= 0 Then
If lngYO >= 0 Then
If lngXO < lWidth Then
If lngYO < lHeight Then
lngColor = surfSource.GetLockedPixel(lngXO, lngYO)
If rgbTransparency = -1 Or lngColor <> rgbTransparency Then
surfDestination.SetLockedPixel XDest + iX, Ydest + iY, lngColor
End If
End If
End If
End If
End If
Next iY
Next iX
surfSource.Unlock rEmpty
surfDestination.Unlock rEmpty2
Width = lWidth / 2 - (iX * CosA + iY * SinA)
height = lHeight / 2 - (iX * SinA - iY * CosA)
End Function


Sorry about the length of the code, hope it's useful though. If you have any trouble using it, drop me an email and I'll see if I can help.
Jim

G'day!

I guess it depends on how it's being used and how we define 'fast enough'.

This approach is heavily CPU-bound. You will get no HW-accelleration at all. Pixel-writing to a video memory surface is very slow, which you can work-around by using a system memory surface for all rendering and then blt that to the back-buffer.

All these criticisms aside, if you're using it on a relatively small number of objects and have a half-decent CPU to run on, it's not going to be an issue.

I just don't see this method being very fast in the general case.

Stay Casual,

Ken