View Full Version : reverse engineer a displaylist

05-22-2002, 12:37 PM
Hi folks,

is it possible to capture the vertex data from a displaylist that was created by wglUseFontOutline?
glTrace does not work, because the wgl-funktions are in the same dll as all other opengl funktions...
Any ideas how to capture the vertex data from the displaylists created by the wgl funktions are wellcome.

Thx for any hints...

05-22-2002, 03:27 PM
"For performance reasons, it was decided that you could not read back what was in a display list."

Someone told me that, but Im not sure if its true. Display lists are likely to be in system memory., but I guess for some hardware....

If you want the text, you can always use the windows specific funtions:

Check out FontFill on MSDN. search for "getting font outlines" also.
It's quite complicated stuff.


05-22-2002, 05:54 PM
you can read back almost everything. just use one of the three rendering modes. i mean feedback mode. i tried it, it works perfectly for wglUseFontOutlines.
the reason i did this is that wglUseFontOutlines failed when using on an RC which was created for a DIB section surface. i still dont know the reason, but i could solve the problem by reading back and storing coordinates and commands in a file, which i read back later when i needed the glyphs.

05-23-2002, 04:56 AM

yes feedback mode is a nice tool. Here at school we have an embedded system which controls a laser to draw lines on a wall. The system is connected to PC via a serial link. On the PC I rendered different objects like spheres, cubes and wglFonts to the feedback buffer and postprocessed them. Then they got transmitted to the laser system and it run fine.
Feedback buffer is really nice, so you can get all geometry and do what you want http://www.opengl.org/discussion_boards/ubb/wink.gif

05-23-2002, 06:50 AM
I also asked for this once.

goto: http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/003380.html

05-23-2002, 02:20 PM
How do you reconstruct the polygons when you get the vertices with feedback mode?

Are you using some algorihtm for that?


05-25-2002, 02:52 AM
Hi again,

thank's for the info about feedback buffer...