PMAP lacks precision

[TempodiBasic]

Hi boys and girls of QB64

trying to develope in alternative way my Pong OpenGl demo by using WINDOW and PMAP commands of QB64/QB
I got PMAP with loosing precision!
please try this code:

Code: QB64: [Select]

1. Dim S As _Unsigned Long
2.  
3. S = _NewImage(800, 600, 32)
4. Screen S
5. Window Screen(-1.0, -1.0)-(1.0, 1.0)
6. ' translate screen left-top and lower-right into window system
7. Print PMap(0, 2), PMap(0, 3), PMap(800, 2), PMap(600, 3)
8.  
9. 'translate window system left-top and lower-right into screen
10. Print PMap(-1, 0), PMap(-1, 1), PMap(1, 0), PMap(1, 1)
11.  
12.  
13.  

and here you can see the output
  [ You are not allowed to view this attachment ]  
Well it seems that we cannot use PMAP for NASA calculation.
Please gimme feedbacks.

[bplus]

Found the loosing here:

Code: QB64: [Select]

1. Dim S As _Unsigned Long
2.  
3. S = _NewImage(800, 600, 32)
4. Screen S
5. Window Screen(-1.0, -1.0)-(1.0, 1.0)
6. ' translate screen left-top and lower-right into window system
7. Print PMap(0, 2), PMap(0, 3), PMap(799, 2), PMap(599, 3)
8.  
9. 'translate window system left-top and lower-right into screen
10. Print PMap(-1, 0), PMap(-1, 1), PMap(1, 0), PMap(1, 1)
11.  
12.  
13.  

What do you think?

[SMcNeill]

Found the loosing here:

Code: QB64: [Select]

1. Dim S As _Unsigned Long
2.  
3. S = _NewImage(800, 600, 32)
4. Screen S
5. Window Screen(-1.0, -1.0)-(1.0, 1.0)
6. ' translate screen left-top and lower-right into window system
7. Print PMap(0, 2), PMap(0, 3), PMap(799, 2), PMap(599, 3)
8.  
9. 'translate window system left-top and lower-right into screen
10. Print PMap(-1, 0), PMap(-1, 1), PMap(1, 0), PMap(1, 1)
11.  
12.  
13.  

What do you think?

I think you’re right, as an 800x600 screen runs from 0 to 799 x 0 to 599.  Tempodi’s values were off the chart.  ;)

[TempodiBasic]

Thanks,
It is always better be helped to find own mistakes.
So I have misunderstood the range of declaration.
My error is that I have thought  about dimensions of screen like we do with array so I have thought 800 is like 0-800 because there is no option base to force to start from 1. And so for the other dimension.
Thanks to point my conceptual error.