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opengl question from a newbie

Hi ,
        I have started working on OpenGL just week back and i am not able to
understad the following . I have just added the routine to initialise the
viewport and clear the drawing form using OpenGL routine . When My DC have
been set using the mapping  mode MM_LOENGLISH  , the form does not get
cleared , when i comment it out it works fine . The reason why i have done
this is because i am working on CAD project and i had moved the viewport
origin to the bottom-left corner .

Can u tell me a work around as all my data is in worlcordinates assuming the
lower left corner . Due to this i am not able to proceed ahead . Any
suggestions will be really appreciated .

How to clear a portion of Window say from (100,100) to (200,200) ?

Lastly Can anyonetell me what is the server name which contains the
newsgroup 'comp.graphics.api.opengl' .

Thanking you very much

Devinder

 

Re:opengl question from a newbie


Clear will set the entire window to the chosen clear color unless you use
scissor. Remember that Viewport uses window coordinates, so its dimensions
will be in pixels. However the y-direction is from bottom to top, so the
origin is in the lower left corner of the window, rather than the upper
left. You can set you viewport anywhere in the window (form) if you remember
that you are measuring from bottom to top of the forms CLIENT area. Once you
have defined your Viewport, you can use numbers meaningful to your "world"
when you set up your projection.
Jon
http://sql.ofthe.net/scripts/wordware/display.idc?id=313

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