access violation when i use my index buffer to draw objects [duplicate] - c++

Question

This question already has answers here:
OpenGL object in C++ RAII class no longer works
(2 answers)
Closed 1 year ago.
I am learning OpenGL and I am trying to abstract it to make it convenient for me to use it.
but I am getting access violations when I use my IndexBuffer class while rendering.
this is my code for IndexBuffer.h
class IndexBuffer
{
public:
IndexBuffer(void* data, int count);
IndexBuffer(int count);
IndexBuffer Bind();
IndexBuffer UnBind();
void AddData(void* data);
~IndexBuffer();
private:
int count;
size_t size;
unsigned int id;
};
and this is my code for IndexBuffer.cpp
#include "IndexBuffer.h"
#include "glew/glew.h"
IndexBuffer::IndexBuffer( void* data, int count): id(0), count(count), size(sizeof(unsigned int)* count)
{
glGenBuffers(1, &id);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, id);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * count, data, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
IndexBuffer::IndexBuffer( int count) : id(0), count(count), size(sizeof(unsigned int)* count)
{
glGenBuffers(1, &id);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, id);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * count, nullptr, GL_DYNAMIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
IndexBuffer IndexBuffer::Bind()
{
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, id);
return *this;
}
IndexBuffer IndexBuffer::UnBind()
{
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
return *this;
}
void IndexBuffer::AddData(void* data)
{
Bind();
glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, sizeof(unsigned int) * count, data);
UnBind();
}
IndexBuffer::~IndexBuffer()
{
glDeleteBuffers(1, &id);
}
I wrote my VertexBuffer in the same way and it works fine, But my index buffer just doesn't work.
this is my main.cpp
#include <iostream>
#include "glew/glew.h"
#include "glfw/glfw3.h"
#include "VertexBuffer.h"
#include "IndexBuffer.h"
struct Vertex
{
float aPos[2];
};
int main() {
GLFWwindow* window;
if (glfwInit() == GLFW_FALSE)
{
return -1;
}
//glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_COMPAT_PROFILE);
window = glfwCreateWindow(600, 600, "Hello world", nullptr, nullptr);
glfwMakeContextCurrent(window);
if (glewInit() != GLEW_OK)
{
return -2;
}
unsigned int index[3] = {
0, 1, 2
};
Vertex data[] = {
Vertex({-0.5f, -0.5f}),
Vertex({ 0.5f, -0.5f}),
Vertex({ 0.0f, 0.5f})
};
unsigned int VertexArrayObject;
glGenVertexArrays(1, &VertexArrayObject);
VertexBuffer buffer = VertexBuffer(sizeof(Vertex) * 3);
IndexBuffer Ibuffer = IndexBuffer( 3);
buffer.Bind();
//glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6, data, GL_STATIC_DRAW);
buffer.AddData(data);
glBindVertexArray(VertexArrayObject);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (const void*)offsetof(Vertex, aPos));
//glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
buffer.UnBind();
Ibuffer.Bind();
Ibuffer.AddData(index);
Ibuffer.UnBind();
while (!glfwWindowShouldClose(window))
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
buffer.Bind();
Ibuffer.Bind();
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteVertexArrays(1, &VertexArrayObject);
glfwDestroyWindow(window);
return 0;
}
can anybody help me out?

Answer 1

In short you have undefined behaviour.
Your classes doesn't support deep copy.
When Bind function returns object (i.e itself) by value, like:
IndexBuffer IndexBuffer::Bind()
destructor of IndexBuffer is called, which deletes previously allocated buffer, so buffer's id is dangled.
All Bind should return reference to instances:
IndexBuffer& IndexBuffer::Bind()