C++ simple glfw/glad setup not rendering triangle - c++

Question

I have written a very basic test setup to render a quad with glfw/glad.
I would expext it to draw a black quad in the middle of the window.
#include <iostream>
#include <array>
#include <cinttypes>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>
using uint32 = std::uint32_t;
using gl_shader_id = GLuint;
gl_shader_id get_shader() {
constexpr auto vertex_shader_source = R"(
#version 460 core
layout (location = 0) in vec3 position;
void main() {
gl_Position = vec4(position.x, position.y, position.z, 1.0);
}
)";
constexpr auto fragment_shader_source = R"(
#version 460 core
out vec4 color;
void main() {
color = vec4(0.0, 0.0, 0.0, 1.0f);
}
)";
const auto vertex_shader = glCreateShader(GL_VERTEX_SHADER);
const auto fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
auto success = 0;
glShaderSource(vertex_shader, 1, &vertex_shader_source, nullptr);
glCompileShader(vertex_shader);
glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
if (!success) {
auto info_log = std::string{};
info_log.reserve(512);
glGetShaderInfoLog(vertex_shader, 512, nullptr, info_log.data());
std::cout << info_log << '\n';
assert(false); // Vertex shader compilation failed
}
glShaderSource(fragment_shader, 1, &fragment_shader_source, nullptr);
glCompileShader(fragment_shader);
if (!success) {
auto info_log = std::string{};
info_log.reserve(512);
glGetShaderInfoLog(fragment_shader, 512, nullptr, info_log.data());
std::cout << info_log << '\n';
assert(false); // Vertex shader compilation failed
}
const auto shader_program = glCreateProgram();
glAttachShader(shader_program, vertex_shader);
glAttachShader(shader_program, fragment_shader);
glLinkProgram(shader_program);
glDetachShader(shader_program, vertex_shader);
glDetachShader(shader_program, fragment_shader);
glDeleteShader(vertex_shader);
glDeleteShader(fragment_shader);
return shader_program;
}
int main() {
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
auto handle = glfwCreateWindow(800, 600, "Hello World", nullptr, nullptr);
glfwMakeContextCurrent(handle);
gladLoadGLLoader(reinterpret_cast<GLADloadproc>(glfwGetProcAddress));
const auto shader_id = get_shader();
const auto vertices = std::array<glm::vec3, 4>{
glm::vec3{ -0.5f, -0.5f, 0.0f },
glm::vec3{ -0.5f, 0.5f, 0.0f },
glm::vec3{ 0.5f, -0.5f, 0.0f },
glm::vec3{ 0.5f, 0.5f, 0.0f }
};
const auto indices = std::array<uint32, 6>{
0, 1, 2,
1, 3, 2
};
auto vertex_array = 0u;
auto vertex_buffer = 0u;
auto index_buffer = 0u;
glGenVertexArrays(1, &vertex_array);
glBindVertexArray(vertex_array);
glGenBuffers(1, &vertex_buffer);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(glm::vec3), vertices.data(), GL_STATIC_DRAW);
glEnableVertexArrayAttrib(vertex_array, 0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(glm::vec3), nullptr);
glGenBuffers(1, &index_buffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(uint32), indices.data(), GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glBindVertexArray(0);
while (!glfwWindowShouldClose(handle)) {
glfwPollEvents();
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(vertex_array);
glUseProgram(shader_id);
glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, nullptr);
glUseProgram(0);
glBindVertexArray(0);
glfwSwapBuffers(handle);
}
glfwDestroyWindow(handle);
glfwTerminate();
return 0;
}
The program and the shader code compile with no error/warnings.
When i execute the program i get the window which is cleared with the right color.
But the quad that i specified with the vertices and indices is not showing up.

Answer 1

I figgured it out after some fiddeling.
For anyone stumbeling uppon this problem.
You have to unbing the vertex array before unbinding the vertex buffer and index buffer.
Otherwise the binding stored inside the vertex array are going to be set to 0 and this nothing can be drawn