add some basic documentation to the backtrace capturing functionality to the README.

1 files changed, 18 insertions, 0 deletions

diff --git a/README.markdown b/README.markdown
index 47f27b86..a08886d8 100644
--- a/README.markdown
+++ b/README.markdown
@@ -67,6 +67,24 @@ You can also tell the GUI to go directly to a specific call
     qapitrace application.trace 12345
 
 
+Backtrace Capturing
+===================
+
+apitrace now has the ability to capture the call stack to an OpenGL call.
+This can be helpful in determing which piece of code made that glDrawArrays call.
+
+*NOTE* this feature is currently only available on Android and Linux at the moment.
+
+On linux you need to have libunwind, and libdwarf installed to compile in the feature.
+
+To use the feature you need to set an environment variable with the list of GL
+call prefixes you wish to capture stack traces to.
+
+    export APITRACE_BACKTRACE="glDraw* glUniform*"
+
+The backtrace data will show up in qapitrace in the bottom section as a new tab.
+
+
 Advanced command line usage
 ===========================