Sprite Masking problem

Me again. Here's a sample program to illustrate the problem. Set the constant at the top to 48, run it, and use the arrow keys to rotate, and the label looks good but has a black box around it. Change the constant to 52, and you should see the weird behavior I described above, rather than the black box just being transparent.

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; This value is the oddball... I need Clamp U and Clamp V flags turned on, so it should be 16+32=48.
; When I turn on masking (4) and use a value of 52, it halves my text and adds a black box.

Global mode = 48 ; switch this between 48 and 52

Global camera_obj
Global light_obj
Global sphere_obj
Global sprite_obj
Global sphere2_obj

Global rot

Global scrap



; initialize graphics modes

Graphics3D maxx, maxy, 16, 1
SetBuffer BackBuffer()



; define camera and light

camera_obj = CreateCamera()
PositionEntity camera_obj, 0, 0, -10

light = CreateLight()
RotateEntity light, 45, 45, 0


; define spheres

sphere_obj = CreateSphere()

sphere2_obj = CreateSphere()
PositionEntity sphere2_obj, -1, -1.5, 5


; draw sphere's label on screen and copy it into texture
; define the label as being 256 pixels across and 32 down

scrap = CreateTexture (256, 32, mode)


; draw the text on this label, then use copyrect to put it in the texture buffer

Cls
Text 128, 0, "This is a sphere", 1
CopyRect 0, 0, 256, 32, 0, 0, BackBuffer(), TextureBuffer(scrap)


; create label sprite and texture it with "scrap"

label_obj = CreateSprite()
PositionEntity label_obj, 0, -1.5, 0
ScaleSprite label_obj, 4, 0.5
EntityTexture label_obj, scrap


; we don't need scrap anymore - clear it out

FreeImage scrap


; draw the world

While Not KeyHit(1)

PositionEntity camera_obj, 0, 0, 0
RotateEntity camera_obj, 0, rot, 0
MoveEntity camera_obj, 0, 0, -10

RenderWorld()
Flip

If KeyDown(203) Then
rot = (rot-2) Mod 360
End If
If KeyDown(205) Then
rot = (rot+2) Mod 360
End If

Wend