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Thread: Help on OpenGL in PaintGL

  1. #1
    Join Date
    Jan 2006
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    Default Help on OpenGL in PaintGL

    Hi I don't undesrtand a thing: I draw with OpenGl a line and I put it in paintGL (and it is OK):
    Qt Code:
    1. //initializeGL()
    2. .....
    3. glEnable(GL_BLEND);
    4. glEnable(GL_LINE_SMOOTH);
    5. glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    6. glHint(GL_LINE_SMOOTH_HINT, GL_DONT_CARE);
    7.  
    8. //paintGL
    9. glLineWidth(3.0);
    10. glColor3f(.9f, .1f, .9f);
    11. glBegin(GL_LINES);
    12. glNormal3f(0.0f, 1.0f, 1.0f);
    13. glVertex3f(X, Y, Z);
    14. glVertex3f(X, Y+3, Z);
    15. glEnd();
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    Then I tried to put above instructions inside a function of onother object (scene::drawLine()
    And I tried this:
    Qt Code:
    1. //paintGL()
    2. scene.drawLine(); // this is OK
    3. scene.drawScene();
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    Qt Code:
    1. Scene::drawScene() {
    2. drawSquare();
    3. }
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    Otherwise:
    Qt Code:
    1. //paintGL()
    2. scene.drawScene() //my line appear aliased!!!
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    Where:
    Qt Code:
    1. Scene::drawScene() {
    2. drawLine();
    3. drawSquare();
    4. }
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    Anyone can tell me about this behavior?
    Thaks
    Last edited by mickey; 14th April 2006 at 17:33.
    Regards

  2. #2
    Join Date
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    Default Re: Help on OpenGL in PaintGL

    This shouldn't happen. I would suggest trying to reproduce the problem in a minimal compilable example, for example by stripping down your program. Either you'll find the error while simplifying the program or you can post the minimal example here.

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