## Forum archive 2000-2006

### Mark Schmitt - Graphics trouble

by Arnold Pizer -
Number of replies: 0
 Graphics trouble topic started 8/28/2001; 9:08:09 PMlast post 9/1/2004; 4:00:15 PM
 Mark Schmitt - Graphics trouble  8/28/2001; 9:08:09 PM (reads: 1517, responses: 5) I'm having trouble using the on-the-fly graphics. I'm using the third conics problem as a test case. In one course, everything works just fine. In a second course, everything seems to work, but the graph is not displayed. The gif file exists in the right place, and I can call it up using a graphics viewer, but on WeBWorK I only get a frame with an "x" in the corner. The code is identical, so I'm pretty sure it must be something in the course set-up, but I have no idea what. Any ideas? Thanks in advance for your help. Mark <| Post or View Comments |>

Michael Gage - Re: Graphics trouble
8/28/2001; 10:45:05 PM (reads: 1815, responses: 0)
These can be hard to trouble shoot.

One thing to remember is that often the browser will not update an image, even when you click reload. A good practice is to hold the shift key down as you click reload since this is more likely to force the graphics to reload.

#### Trouble shoot path -- with .html file if needed

Next, can you call the graph up directly, e.g. by clicking on the non-displaying graph to get an enlarged version, or by entering what should be the correct address directly into the webbrowser. If you can't view the graph that way there is a reasonable chance that either the .gif file itself or one of the directories above it doesn't have the correct permission. This can be quite tedious to track down. Place a .gif file that you know works in the appropriate directory and see if you can view that -- or just place a text file there. Make sure the path is clear all the way from the top directory to the target file.

The URL usually points to some top level directory accessed by the webserver. There may need to be a link from this directory (or one of its subdirectories) to the directory containing the .gif file. You might have forgotten to create this link for one of your courses.

I hope this helps some. Mostly it takes patience, I've spent more than my share of hours tracking down permission problems or missing links in paths.

Let me know if it turns out to be something else. We'll add it to the checklist.

-- Mike

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 Mark Schmitt - Re: Graphics trouble  8/29/2001; 10:17:31 AM (reads: 1848, responses: 1) Thanks Mike. The gif was working correctly when I typed the URL myself, so I noticed that my $htmlURL was set incorrectly in webworkCourse.ph. When I added the appropriate directory in that spot, I got everything working. In short, I missed a needed directory when I ran the courseSetUp script. Editting the$htmlURL value in webworkCourse.ph fixed the problem. Thanks again for pointing me on the right path. Mark <| Post or View Comments |>

 Andras Balogh - Re: Graphics trouble  9/1/2004; 1:36:01 PM (reads: 1772, responses: 0) Mark, Was it enough to correct the htmlURL path in webworkCourse.ph ? I made the same mistake, but correcting this one line does not seem to solve the problem. I am afraid I will have to set up the course from scratch again. Andras <| Post or View Comments |>

 Mark Schmitt - Re: Graphics trouble  9/1/2004; 3:34:55 PM (reads: 1421, responses: 0) Andras, Correcting the htmlURL did fix the problem for me. I actually had another instance of this problem just last week, and fixing the htmlURL fixed that problem as well. Double check that the permissions on the directory are correct as well, since that is another issue I have run into in the past. Mark <| Post or View Comments |>

 Andras Balogh - Re: Graphics trouble  9/1/2004; 4:00:15 PM (reads: 1424, responses: 0) Thank you Mark, Correcting the htmlURL would have indeed resolved the problem, unless I renamed the symbolic link and then I forgot the new name. :-( Andras <| Post or View Comments |>