c++ opengl nvoglv32.dll error

OpenGL OpenGL: Basic Coding
1

have a sprite class to handle initializing a sprite and drawing it but i keep getting this error “Exception thrown at 0x69B3C760 (nvoglv32.dll) in Flora.exe: 0xC0000005: Access violation reading location 0x00000000.” I’m not exactly sure what is causing this. Here’s the source code for it

void Sprite::init(int vertNum, float r, Shape shape) {
    _vertNum = vertNum;
    if (_vboID = 0) {
        glGenBuffers(1, &_vboID);
    }
    std::vector<Vertex> vertexData(vertNum);
    if (shape == Shape::CIRCLE) {
        for (int i = 0; i < vertNum; i++) {
            vertexData[i].setPosition(r*cos(i), r*sin(i));
        }
    }
    for (int i = 0; i < _vertNum; i++) {
        vertexData[i].setColor(1, 1, 1, 1);
    }
    glBindBuffer(GL_VERTEX_ARRAY, _vboID);
    glBufferData(GL_VERTEX_ARRAY, sizeof(vertexData), vertexData.data(), GL_DYNAMIC_DRAW);
    glBindBuffer(GL_VERTEX_ARRAY, 0);
}

void Sprite::draw() {
    //bind buffer array
    glBindBuffer(GL_ARRAY_BUFFER, _vboID);

    //use first vertex attrib array
    glEnableVertexAttribArray(0);

    //pointer to vertices location
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, position));
    //pointer to vertices color
    glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, color));

    //Draw the 6 vertices to the screen
    glDrawArrays(GL_POLYGON, 0, _vertNum);

    //Disable the vertex attrib array. This is not optional.
    glDisableVertexAttribArray(0);

    //Unbind the VBO
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}
2

You mean == instead of =
In your case the condition will never be satisfied and you will operate on a buffer that does not exist.

3

[QUOTE=Spoops;1282490]You mean == instead of =
In your case the condition will never be satisfied and you will operate on a buffer that does not exist.[/QUOTE]

oh wow i can’t believe i missed that, how ever now it’s giving me a different error. The message it gives is “Exception thrown at 0x00BBFDB5 in Flora.exe: 0xC0000005: Access violation reading location 0x00000000.”. im not sure what these mean are they error codes? if so where can i find what they mean? sorry for the newbie questions im very new to c++ and opengl

4

They mean that you have a NULL pointer somewhere.

However, I suggest you fix this first:

glBindBuffer(GL_VERTEX_ARRAY, _vboID);
glBufferData(GL_VERTEX_ARRAY, sizeof(vertexData), vertexData.data(), GL_DYNAMIC_DRAW);
glBindBuffer(GL_VERTEX_ARRAY, 0);

Should be GL_ARRAY_BUFFER, not GL_VERTEX_ARRAY.

Then you can move on to the fact that you’re drawing from attrib arrays 0 and 1 but only enabling attrib array 0.

5

[QUOTE=mhagain;1282499]They mean that you have a NULL pointer somewhere.

However, I suggest you fix this first:

glBindBuffer(GL_VERTEX_ARRAY, _vboID);
glBufferData(GL_VERTEX_ARRAY, sizeof(vertexData), vertexData.data(), GL_DYNAMIC_DRAW);
glBindBuffer(GL_VERTEX_ARRAY, 0);

Should be GL_ARRAY_BUFFER, not GL_VERTEX_ARRAY.

Then you can move on to the fact that you’re drawing from attrib arrays 0 and 1 but only enabling attrib array 0.[/QUOTE]

Ah ok I was following some tutorial and looked and I guess the source code he offered wasn’t 100% right. anyways thank you so much for your help!