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Thread: Vertex Buffer Object -> Segmentation Fault

  1. 4th March 2014, 02:37 #1
    BlastDV
    BlastDV is offline Beginner
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    Default Vertex Buffer Object -> Segmentation Fault

    Hi everyone, I've been developing a 3D creator but I'm still stuck in the first stages since I haven't been able to draw with VBO.

    This is a piece of my glwidget.cpp code, where all the objects are drawn
    Qt Code: 
    1. void GLWidget::initializeGL()
    2. {
    3.     #define PROGRAM_VERTEX_ATTRIBUTE 0
    4.     #define PROGRAM_NORMALS_ATTRIBUTE 1
    5.  
    6.     //glEnable(GL_DEPTH_TEST);
    7.     //glEnable(GL_CULL_FACE);
    8.  
    9.  
    10.     vShader= new QGLShader (QGLShader::Vertex, this);
    11.     vShader->compileSourceFile("../src/shaders/editorVshader.glsl");
    12.  
    13.     fShader= new QGLShader (QGLShader::Fragment, this);
    14.     fShader->compileSourceFile("../src/shaders/editorFshader.glsl");
    15.  
    16.     editor= new QGLShaderProgram (this);
    17.     editor->addShader(vShader);
    18.     editor->addShader(fShader);
    19.     editor->bindAttributeLocation("vertices", PROGRAM_VERTEX_ATTRIBUTE);
    20.     editor->bindAttributeLocation("normals", PROGRAM_NORMALS_ATTRIBUTE);
    21.     editor->link();
    22.     editor->bind();
    23. }
    24.  
    25. void GLWidget::paintGL()
    26. {
    27.     glClearColor(0.4765625, 0.54296875, 0.6171875, 1.0);
    28.     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    29. /*
    30.     glLoadIdentity();
    31.     glTranslatef(0.0f, 0.0f, -10.0f);
    32. */
    33.  
    34.     editor->setUniformValue("projectMatrix", controller->getProjectionMatrix());
    35.     editor->setUniformValue("viewMatrix", controller->getViewMatrix());
    36.  
    37.  
    38.     /** Ahora para las operaciones especificas de cada objeto **/
    39.  
    40.     for (int i=0; i<Objects.size(); i++)
    41.     {
    42.         Objects[i].modelmatrix.scale(1.0, 1.0, 1.0);
    43.         Objects[i].modelmatrix.rotate(1.0, 0.0, 0.0, 1.0);
    44.         editor->setUniformValue("modelMatrix", Objects.at(i).modelmatrix);
    45.  
    46.         glEnableClientState(GL_VERTEX_ARRAY);
    47.         Objects[i].vertexbuffer->bind();
    48.         glVertexPointer(3, GL_FLOAT, 0, Objects.at(i).indexed_vertices.data());
    49.         editor->enableAttributeArray("vertices");
    50.         editor->setAttributeBuffer("vertices", GL_FLOAT, 0, Objects[i].indexed_vertices.size() * sizeof(vertex)); // (PROGRAM_VERTEX_ATTRIBUTE, Objects[i].vertices.data());
    51. /*
    52.         Objects[i].normalbuffer.bind();
    53.         //glVertexPointer(3, GL_FLOAT, 3, Objects.at(i).indexed_normals.data());
    54.         glEnableClientState(GL_NORMAL_ARRAY);
    55.         editor->enableAttributeArray(PROGRAM_NORMALS_ATTRIBUTE);
    56.         editor->setAttributeBuffer (PROGRAM_NORMALS_ATTRIBUTE, GL_FLOAT, 0, Objects[i].indexed_normals.size() * sizeof(vertex));*/
    57.  
    58.         //glDrawArrays(GL_QUADS, 0, Objects[i].vertices.size());
    59.         Objects[i].elementbuffer->bind();
    60.         glDrawElements(GL_QUADS, Objects[i].indices.size(), GL_UNSIGNED_SHORT, (void*)0);
    61.     }
    62. }
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    It explodes when it tries to execute the glDrawElements instruction. I've been tracking down the problem but I can't find what's wrong. I'm even doubting about the right way to use QGLBuffer in Qt. Can anyone help me?
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  2. 4th March 2014, 15:15 #2
    BlastDV
    BlastDV is offline Beginner
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    Default Re: Vertex Buffer Object -> Segmentation Fault

    Hi, I solved it. The problem was the “tuplasize” that I was using with the setAttributeBuffer instruction.

    It was

    Qt Code: 
    1. Objects[i].indexed_vertices.size() * sizeof(vertex)
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    Now I changed it to 3 and started passing normals as vertices too, the result code is:

    Qt Code: 
    1. void GLWidget::paintGL()
    2. {
    3.     glClearColor(0.4765625, 0.54296875, 0.6171875, 1.0);
    4.     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    5. /*
    6.     glLoadIdentity();
    7.     glTranslatef(0.0f, 0.0f, -10.0f);
    8. */
    9.  
    10.     editor->setUniformValue("projectMatrix", controller->getProjectionMatrix());
    11.     editor->setUniformValue("viewMatrix", controller->getViewMatrix());
    12.  
    13.  
    14.     /** Ahora para las operaciones especificas de cada objeto **/
    15.  
    16.     for (int i=0; i<Objects.size(); i++)
    17.     {
    18.         Objects[i].modelmatrix.scale(1.0, 1.0, 1.0);
    19.         Objects[i].modelmatrix.rotate(1.0, 0.0, 0.0, 1.0);
    20.         editor->setUniformValue("modelMatrix", Objects.at(i).modelmatrix);
    21.  
    22.         glEnableClientState(GL_VERTEX_ARRAY);
    23.         editor->enableAttributeArray("vertices");
    24.         Objects[i].vertexbuffer->bind();
    25.         //glVertexPointer(3, GL_FLOAT, 0, Objects.at(i).indexed_vertices.data());
    26.         editor->setAttributeBuffer("vertices", GL_FLOAT, 0, 3); // (PROGRAM_VERTEX_ATTRIBUTE, Objects[i].vertices.data());
    27.         //glDisableClientState(GL_VERTEX_ARRAY);
    28.  
    29.         //glEnableClientState(GL_NORMAL_ARRAY);
    30.         editor->enableAttributeArray("normals");
    31.         Objects[i].normalbuffer->bind();
    32.         //glVertexPointer(3, GL_FLOAT, 3, Objects.at(i).indexed_normals.data());
    33.         editor->setAttributeBuffer ("normals", GL_FLOAT, 0, 3);
    34.         glDisableClientState(GL_VERTEX_ARRAY);
    35.  
    36.         //glDrawArrays(GL_QUADS, 0, Objects[i].vertices.size());
    37.         Objects[i].elementbuffer->bind();
    38.         glDrawElements(GL_QUADS, Objects[i].indices.size(), GL_UNSIGNED_SHORT, (void*)0);
    39.     }
    40. }
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    Consider this thread as solved
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