Rookie rotation issue?
Ok this is probably a rookie mistake caused by my ignorance, but if anyone could spot the mistake I would be most grateful
This is what is happening in my app....
The user uses the LHM button to dynamically rotate/pan/zoom.
I use a class based on Ken Schomakers Arc ball. This basically returns a matrix ---- mNow
This works fine.
However I would like to put a few buttons in my app for standard views XY, YZ etc
I have done this like so --- Press a button and do,,,,
glRotatef 180, 0, 1, 0
Now the problem/issue.
1. Imagine you have rotated the model with the mouse to some arbitrary position.
2. You then press the XY view button and the model moves to the XY view.
3. You now wish to rotate the model again via the mouse.
You (the user) would expect the model to rotate from an XY start position (position 2)
What happens is that as soon as you click the mouse in the graphics region the model 'flicks' back to its position at 1 above and does not start from the XY position. It just looks wrong.
Its driving me nuts...
I suspect its some sort of matrix stack thing but I don't know really...
The code (editited to remove stuff not relevant??) is below
Can anyone spot the mistake?
(edit - the code indentations have gone - sorry)
Public Sub Draw()
'This is where all the action takes place
'All the OGL rendering is done here
Dim mNow!(0 To 15), radius!
'This parameter sets the scale for the view based on the Ball Rad
'This is used as a zoom
radius = Ball.radius * sngZoomFactor
glScalef radius, radius, radius
Select Case gintView
Case 1 '1=XY Top
Case 2 '2=XY Bottom
glRotatef 180, 0, 1, 0
Case 3 '3=XZ Front
glRotatef 90, 1, 0, 0
Case 4 '4=XZ Back
glRotatef -90, 1, 0, 0
Case 5 '5=YZ Left
glRotatef 90, 0, 1, 0
Case 6 '6=YZ Right
glRotatef -90, 0, 1, 0
Case 7 '7=ISO
glRotatef 45, 0, 1, 0
glRotatef 10, 1, 0, 0
THE OGL DISPLAY LIST STUFF IS HERE
Re: Rookie rotation issue?
Thinking about it...
Is it a case that mNow is set at some arbitrary rotation/view and isn't being set to the XY view matrix when I press the button?
Edit Hmmmm just tried this crude load of mNow
mNow(0) = 1
mNow(1) = 0
mNow(2) = 0
mNow(3) = 0
mNow(4) = 0
mNow(5) = 1
mNow(6) = 0
mNow(7) = 0
mNow(8) = 0
mNow(9) = 0
mNow(10) = 1
mNow(11) = 0
mNow(12) = 0
mNow(13) = 0
mNow(14) = 0
mNow(15) = 1
When I comment out the glLoadIdentity line the model doesn't move back (the problem)... However, it doesn't seem to do anything... It doesnt move at all!
I bet this is a really simple/daft one :-)