VAO

unsigned int offset = 0;
    unsigned int multiplier = 3;
    if (hasTextCoord) {
        multiplier += 2;
    }
    if (hasNormCoord) {
        multiplier += 3;
    }
    if (normalMapping) {
        multiplier += 6;
    }

    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);

    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, meshData.amountVertices * sizeof(GLfloat), &meshData.vertices[0], GL_STATIC_DRAW);

    // set the vertices
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, multiplier * sizeof(GLfloat), (GLvoid*)offset);
    glEnableVertexAttribArray(0);
    offset += 3;
    // set the textCoordinates
    if (hasTextCoord && enableTextCoord) {
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, multiplier * sizeof(GLfloat), (GLvoid*)(offset * sizeof(GLfloat)));
        glEnableVertexAttribArray(1);
        offset += 2;
    }
    else if (hasTextCoord && !enableTextCoord) {
        offset += 2;
    }
    // set the normalCoordinates
    if (hasNormCoord && enableNormCoord) {
        glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, multiplier * sizeof(GLfloat), (GLvoid *)(offset * sizeof(GLfloat)));
        glEnableVertexAttribArray(2);
        offset += 3;
    }
    else if (hasNormCoord && !enableNormCoord) {
        offset += 3;
    }
    if (normalMapping) {
        // set the tangent
        glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, multiplier * sizeof(GLfloat), (GLvoid *)(offset * sizeof(GLfloat)));
        glEnableVertexAttribArray(3);
        offset += 3;
        // set the bitangent
        glVertexAttribPointer(4, 3, GL_FLOAT, GL_FALSE, multiplier * sizeof(GLfloat), (GLvoid *)(offset * sizeof(GLfloat)));
        glEnableVertexAttribArray(4);
        offset += 3;
    }
    glBindVertexArray(0);
    this->amountVertices = meshData.amountVertices;
    delete meshData.vertices;
}