Psychtoolbox OpenGL - draw a line

Question

I need is a single line rendered from within PsychToolBox in Matlab. So:

glBegin(GL.LINES);
glVertex3f(0, 0, 0);
glVertex3f(1, 1, 1);
glEnd;

Returns:

??? The class "GL" is undefined. Perhaps Java is not running.

I'm using the code provided here.

However, I substituted GL_LINES with GL.LINES to fit psychtoolbox convention (naturally, tried it both ways).

score 3 · Accepted Answer · answered Mar 26 '15 at 11:19

3

I had a similar issue when I added a subfunction that was fixed by making GL a global variable:

function parent()
    global GL
    InitializeMatlabOpenGL(0);
    ...
    function child()
        ...
    end
end

answered Mar 26 '15 at 11:19

Steve

78
1
8

Yes, definitely, making the declaration `global GL` solves the issue. – linello Oct 10 '16 at 11:06

score 1 · Answer 2 · answered Nov 29 '14 at 03:25

1

I neglected to mention that the above lines were run from a subfunction. Whenever this is done, apparently I need to explicitly pass the "GL" structure from the function that runs Screen('BeginOpenGL'). Let me know if anyone else experiences the above issue, and if you need more details about this answer.

answered Nov 29 '14 at 03:25

egor.ananyev

347
4
9

Same problem happens for me. Subfunctions need to have the GL structure passed. I thought GL was a static variable visible from everywhere. – linello Oct 10 '16 at 11:05

Psychtoolbox OpenGL - draw a line

2 Answers2