BigD

10-30-2001, 01:21 PM

It sure would be nice if there were a way for GL to internally use double precision floating point values.

I am trying to display real world data and I lose precision when my values get to be larger than 10 million even though I specify the glVertex3d() to send double-precision values into gl.

I am guessing that gl internally stores values with only single precision. In the posts that I have read, people shun the use of double precision values. This is where one can see the obvious difference between engineers with real world experience and computer science majors without it. News Flash: not everybody uses GL for games or other fictional world locations.

Not to make any of you feel bad, but the software I develop represents real world locations using real world units (UTM, State Plane, etc.). You cannot just say "move your city closer to the equator" so that GL can handle your coordinate system.

What it appears that I will be required to do, is to keep track of a coordinate system offset value (x,y,z), and subtract this value from each vertex that I give to GL. This way, I can allow the user to work with his data in a real coordinate system, but handle these unfortunate GL limitations by giving GL values within single precision tolerances. What a nightmare this will be!

Perhaps someone else knows an existing trick to force GL to work (INTERNALLY) with double precision values??

I am trying to display real world data and I lose precision when my values get to be larger than 10 million even though I specify the glVertex3d() to send double-precision values into gl.

I am guessing that gl internally stores values with only single precision. In the posts that I have read, people shun the use of double precision values. This is where one can see the obvious difference between engineers with real world experience and computer science majors without it. News Flash: not everybody uses GL for games or other fictional world locations.

Not to make any of you feel bad, but the software I develop represents real world locations using real world units (UTM, State Plane, etc.). You cannot just say "move your city closer to the equator" so that GL can handle your coordinate system.

What it appears that I will be required to do, is to keep track of a coordinate system offset value (x,y,z), and subtract this value from each vertex that I give to GL. This way, I can allow the user to work with his data in a real coordinate system, but handle these unfortunate GL limitations by giving GL values within single precision tolerances. What a nightmare this will be!

Perhaps someone else knows an existing trick to force GL to work (INTERNALLY) with double precision values??