rem
bbdoc: Set the rotation of the viewport
about: SetViewRotation allows you to rotate the entire viewport, so that all
drawing is rotated according to the @angle parameter.
endrem
Function SetViewRotation(angle:Float)
   
   Global o_angle:Float
   
   glMatrixMode GL_PROJECTION
   glRotatef angle-o_angle,0,0,1
   o_angle=angle
   
   glMatrixMode GL_MODELVIEW
   glLoadIdentity
   
End Function

rem
bbdoc: Set the offset of the viewport
about: SetViewOffset allows you to offset the entire viewport, so that all
drawing is offset according to the @offsetx and @offsety parameters.
endrem
Function SetViewOffset(offsetx:Float,offsety:Float)
   
   Global o_offsetx:Float
   Global o_offsety:Float
   
   glMatrixMode GL_PROJECTION
   glTranslatef offsetx-o_offsetx,offsety-o_offsety,0
   o_offsetx = offsetx
   o_offsety = offsety
   
   glMatrixMode GL_MODELVIEW
   glLoadIdentity
   
End Function

rem
bbdoc: Set the zoom factor of the viewport
about: SetViewZoom allows you to zoom all drawn elements at once, instead
of scaling each individual element. Use the @zoom parameter to define the
level of zoom, a value of 0 is the default zoom, >0 zooms in, <0 zooms out.
endrem
Function SetViewZoom(zoom:Float)
   
   Global o_zoom:Float
   
   glMatrixMode GL_PROJECTION
   glScalef 1.0+(zoom-o_zoom),1.0+(zoom-o_zoom),1.0+(zoom-o_zoom)
   o_zoom = zoom
   
   glMatrixMode GL_MODELVIEW
   glLoadIdentity
   
End Function