[Solved]Vertex Buffer Object -> Segmentation Fault

[BlastDV]

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
@void GLWidget::initializeGL()
{
#define PROGRAM_VERTEX_ATTRIBUTE 0
#define PROGRAM_NORMALS_ATTRIBUTE 1

//glEnable(GL_DEPTH_TEST);
//glEnable(GL_CULL_FACE);


vShader= new QGLShader (QGLShader::Vertex, this);
vShader->compileSourceFile("../src/shaders/editorVshader.glsl");

fShader= new QGLShader (QGLShader::Fragment, this);
fShader->compileSourceFile("../src/shaders/editorFshader.glsl");

editor= new QGLShaderProgram (this);
editor->addShader(vShader);
editor->addShader(fShader);
editor->bindAttributeLocation("vertices", PROGRAM_VERTEX_ATTRIBUTE);
editor->bindAttributeLocation("normals", PROGRAM_NORMALS_ATTRIBUTE);
editor->link();
editor->bind();

}

void GLWidget::paintGL()
{
glClearColor(0.4765625, 0.54296875, 0.6171875, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
/*
glLoadIdentity();
glTranslatef(0.0f, 0.0f, -10.0f);
*/

editor->setUniformValue("projectMatrix", controller->getProjectionMatrix());
editor->setUniformValue("viewMatrix", controller->getViewMatrix());


/** Ahora para las operaciones especificas de cada objeto **/

for (int i=0; i<Objects.size(); i++)
{
    Objects[i].modelmatrix.scale(1.0, 1.0, 1.0);
    Objects[i].modelmatrix.rotate(1.0, 0.0, 0.0, 1.0);
    editor->setUniformValue("modelMatrix", Objects.at(i).modelmatrix);

    glEnableClientState(GL_VERTEX_ARRAY);
    Objects[i].vertexbuffer->bind();
    glVertexPointer(3, GL_FLOAT, 0, Objects.at(i).indexed_vertices.data());
    editor->enableAttributeArray("vertices");
    editor->setAttributeBuffer("vertices", GL_FLOAT, 0, Objects[i].indexed_vertices.size() * sizeof(vertex)); // (PROGRAM_VERTEX_ATTRIBUTE, Objects[i].vertices.data());

/*
Objects[i].normalbuffer.bind();
//glVertexPointer(3, GL_FLOAT, 3, Objects.at(i).indexed_normals.data());
glEnableClientState(GL_NORMAL_ARRAY);
editor->enableAttributeArray(PROGRAM_NORMALS_ATTRIBUTE);
editor->setAttributeBuffer (PROGRAM_NORMALS_ATTRIBUTE, GL_FLOAT, 0, Objects[i].indexed_normals.size() * sizeof(vertex));*/

    //glDrawArrays(GL_QUADS, 0, Objects[i].vertices.size());
    Objects[i].elementbuffer->bind();
    glDrawElements(GL_QUADS, Objects[i].indices.size(), GL_UNSIGNED_SHORT, (void*)0);
}

}@

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?

[Nexelen]

bq. Warning: Apart from the QGLWidget class, this module should not be used anymore for new code. Please use the corresponding OpenGL classes in Qt Gui.

Use new classes for OpenGL application: QOpenGLBuffer, QOpenGLShaderProgram...

[BlastDV]

Hi, thanks for your answer.

I'm using QGLShaderProgram and QGLBuffer is called inside of QtOpenGL.

Do you mean that Qt4.8's OpenGL classes are so deprecated that they don't even work?

[BlastDV]

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

It was @Objects[i].indexed_vertices.size() * sizeof(vertex)@

Now I changed it to 3 and started passing normals as vertices too, the result code is:

@void GLWidget::paintGL()
{
glClearColor(0.4765625, 0.54296875, 0.6171875, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
/*
glLoadIdentity();
glTranslatef(0.0f, 0.0f, -10.0f);
*/

editor->setUniformValue("projectMatrix", controller->getProjectionMatrix());
editor->setUniformValue("viewMatrix", controller->getViewMatrix());


/** Ahora para las operaciones especificas de cada objeto **/

for (int i=0; i<Objects.size(); i++)
{
    Objects[i].modelmatrix.scale(1.0, 1.0, 1.0);
    Objects[i].modelmatrix.rotate(1.0, 0.0, 0.0, 1.0);
    editor->setUniformValue("modelMatrix", Objects.at(i).modelmatrix);

    glEnableClientState(GL_VERTEX_ARRAY);
    editor->enableAttributeArray("vertices");
    Objects[i].vertexbuffer->bind();
    //glVertexPointer(3, GL_FLOAT, 0, Objects.at(i).indexed_vertices.data());
    editor->setAttributeBuffer("vertices", GL_FLOAT, 0, 3); // (PROGRAM_VERTEX_ATTRIBUTE, Objects[i].vertices.data());
    //glDisableClientState(GL_VERTEX_ARRAY);

    //glEnableClientState(GL_NORMAL_ARRAY);
    editor->enableAttributeArray("normals");
    Objects[i].normalbuffer->bind();
    //glVertexPointer(3, GL_FLOAT, 3, Objects.at(i).indexed_normals.data());
    editor->setAttributeBuffer ("normals", GL_FLOAT, 0, 3);
    glDisableClientState(GL_VERTEX_ARRAY);

    //glDrawArrays(GL_QUADS, 0, Objects[i].vertices.size());
    Objects[i].elementbuffer->bind();
    glDrawElements(GL_QUADS, Objects[i].indices.size(), GL_UNSIGNED_SHORT, (void*)0);
}

}@

I will mark this as SOLVED.