. Quad disappears once i moved it into a seperate class

Question

I finally got a quad working with textures, and to clean up my code, I decided to move it into a separate class, but now it disappeared without any error message.

Main file:

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <stb/stb_image.h>

#include <texture.h>
#include <window.h>
#include <shader.h>
#include <model.h>

#include <iostream>

GLfloat vertexes[]
{
    0.5,  0.5, 0.0,   1.0, 0.0, 0.0,   1.0, 1.0,
   -0.5, -0.5, 0.0,   0.0, 1.0, 0.0,   0.0, 0.0,
    0.5, -0.5, 0.0,   0.0, 0.0, 1.0,   1.0, 0.0,

    0.5,  0.5, 0.0,   1.0, 0.0, 0.0,   1.0, 1.0,
   -0.5,  0.5, 0.0,   1.0, 1.0, 1.0,   0.0, 1.0,
   -0.5, -0.5, 0.0,   0.0, 1.0, 0.0,   0.0, 0.0
};

const int width = 1900;
const int height = 1200;

int main()
{
    glfwInit();

    window window(width, height, "Voxel Engine");

    gladLoadGL();
    
    glViewport(0, 0, width, height);

    // shader
    shader_program shader("src/shaders/vertex_shader.shader", "src/shaders/fragment_shader.shader");

    model model1(vertexes);

    /*// vao and vbo
    unsigned int vbo, vao;

    glGenBuffers(1, &vbo);

    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexes), vertexes, GL_STATIC_DRAW);

    glGenVertexArrays(1, &vao);

    glBindVertexArray(vao);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);

    glBindVertexArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);*/

    texture test_img("resources/test_img.png", GL_TEXTURE0, GL_RGB, GL_UNSIGNED_BYTE);
    test_img.uniform_shader(shader, "tex_0", 0);

    while (!glfwWindowShouldClose(window.glfw_window))
    {
        glfwPollEvents();

        glClearColor(0.08, 0.12, 0.24, 1.0);
        glClear(GL_COLOR_BUFFER_BIT);

        shader.use();

        //glBindTexture(GL_TEXTURE_2D, texture1);
        test_img.bind();

        glBindVertexArray(model1.vao);

        glDrawArrays(GL_TRIANGLES, 0, 6);

        window.swap_buffers();
    }

    glDeleteVertexArrays(1, &model1.vao);

    glDeleteBuffers(1, &model1.vbo);

    //glDeleteTextures(1, &texture1);

    test_img.destroy();
    shader.destroy();
    window.destroy();

    glfwTerminate();
    return 0;
}

Model header:

#ifndef MODEL_CLASS_H
#define MODEL_CLASS_H

#include <glad/glad.h>

class model
{
    public:
        unsigned int vao, vbo;

        model(GLfloat vertexes[]);

        void render();

        void destroy();
};

#endif

and finally, Model c++ file:

#include <model.h>

model::model(GLfloat vertexes[])
{
    // vao and vbo
    glGenBuffers(1, &vbo);

    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexes), vertexes, GL_STATIC_DRAW);

    glGenVertexArrays(1, &vao);

    glBindVertexArray(vao);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);

    glBindVertexArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

I found that for some reason the vbo and vao werent being created correctly, but what confused me was that I directly copied the code from my main.cpp file, yet now it doesnt work.

Answer 1

The error is here

glBufferData(GL_ARRAY_BUFFER, sizeof(vertexes), vertexes, GL_STATIC_DRAW);

In your new code vertexes is a pointer. It is not possible to have an array parameter in C++, it is always converted to a pointer instead. Therefore sizeof(vertexes) returns the size of the pointer, not the size of the original array. Pass the size in as a separate parameter.

model::model(GLfloat* vertexes, size_t vertex_size)
{
    ...
    glBufferData(GL_ARRAY_BUFFER, vertex_size, vertexes, GL_STATIC_DRAW);
    ...
}