.TH checks 7 "May 2006" BUGLE "User manual"
.SH NAME
checks \- check for errors that OpenGL defines as undefined behaviour
.SH SYNOPSIS
.nf
filterset checks
.fi
.SH DESCRIPTION
While OpenGL checks for many error conditions, there are some for which
the specification does not define behaviour. These instances are
usually in performance-critical paths where error-checking would impact
on performance. This filter-set checks for some of these conditions.
Because of the high cost of the checks, it is only intended for
debugging.

The checks that are made are for
.IP \(bu
Sourcing vertex or index data from unreadable client memory.
.IP \(bu
Sourcing vertex or index data from outside the valid range of a vertex
buffer object.
.IP \(bu
Calling
.B glVertex
from outside of
.BR glBegin / glEnd .
.IP \(bu
Setting client state from inside
.BR glBegin / glEnd .
.IP \(bu
Specifying indices to
.BR glDrawRangeElements (3)
that are outside the specified range.
.P
When an error is detected, a warning is written to standard error and
the call is ignored. There is currently no convenient way to trap the
errors in a debugger (you can, however, find the message in the
.B bugle
source and set a breakpoint on the appropriate line).
.SH BUGS
Due to the design of C, there is no way to perfectly reliably check
for vertex array overruns, although memory debuggers can help.

Mesa, up to 6.5.1, has a bug that prevents generic attribute vertex
from being validated.
.SH AUTHOR
.B gldb
and the
.B bugle
library are written and maintained by Bruce Merry
<bmerry@users.sourceforge.net>.
.SH SEE ALSO
.BR bugle (3),
.BR bugle-unwindstack (7)