I am trying to build an application in C++ with ImGUI, OpenGL and GLFW.
However, when i try to run my program, i get a white screen that then crashes and gives me an error code of -1073741819.
Here is my Class for creating a window, alot of the stuff i copied from the ImGUI opengl3 example:
#include <imgui_impl_glfw.h>
#include <imgui_impl_opengl3.h>
#include <imgui_internal.h>
#include "imgui.h"
#include "AppWindow.h"
static void glfw_error_callback(int error, const char* description)
{
fprintf(stderr, "GLFW Error %d: %s\n", error, description);
}
AppWindow::AppWindow(const char* title, int width, int height)
{
glfwSetErrorCallback(glfw_error_callback);
if (!glfwInit())
return ;
// Decide GL+GLSL versions
#if defined(IMGUI_IMPL_OPENGL_ES2)
// GL ES 2.0 + GLSL 100
const char* glsl_version = "#version 100";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
#elif defined(__APPLE__)
// GL 3.2 + GLSL 150
const char* glsl_version = "#version 150";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 3.2+ only
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Required on Mac
#else
// GL 3.0 + GLSL 130
const char* glsl_version = "#version 130";
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
//glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 3.2+ only
//glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // 3.0+ only
#endif
// Create window with graphics context
window = glfwCreateWindow(width, height, title, nullptr, nullptr);
if (window == nullptr)
return ;
glfwMakeContextCurrent(window);
glfwSwapInterval(1); // Enable vsync
// Setup Dear ImGui context
IMGUI_CHECKVERSION();
ImGui::CreateContext();
io = ImGui::GetIO(); (void)io;
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls
io.ConfigFlags |= ImGuiConfigFlags_DockingEnable; // Enable Docking
io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable; // Enable Multi-Viewport / Platform Windows
//io.ConfigViewportsNoAutoMerge = true;
//io.ConfigViewportsNoTaskBarIcon = true;
// Setup Dear ImGui style
ImGui::StyleColorsDark();
//ImGui::StyleColorsLight();
// When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
ImGuiStyle& style = ImGui::GetStyle();
if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
style.WindowRounding = 0.0f;
style.Colors[ImGuiCol_WindowBg].w = 1.0f;
}
// Setup Platform/Renderer backends
ImGui_ImplGlfw_InitForOpenGL(window, true);
ImGui_ImplOpenGL3_Init(glsl_version);
// Our state
bool show_demo_window = true;
bool show_another_window = false;
}
AppWindow::~AppWindow()
{
#ifdef __EMSCRIPTEN__
EMSCRIPTEN_MAINLOOP_END;
#endif
// Cleanup
ImGui_ImplOpenGL3_Shutdown();
ImGui_ImplGlfw_Shutdown();
ImGui::DestroyContext();
glfwDestroyWindow(window);
glfwTerminate();
return;
}
void AppWindow::setUpdateFunction(void (*function)())
{
updateFunction = function;
}
void AppWindow::update()
{
if (updateFunction != nullptr)
updateFunction();
}
void AppWindow::run()
{
#ifdef __EMSCRIPTEN__
// For an Emscripten build we are disabling file-system access, so let's not attempt to do a fopen() of the imgui.ini file.
// You may manually call LoadIniSettingsFromMemory() to load settings from your own storage.
io.IniFilename = nullptr;
EMSCRIPTEN_MAINLOOP_BEGIN
#else
while (!glfwWindowShouldClose(window))
#endif
{
// Poll and handle events (inputs, window resize, etc.)
// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
glfwPollEvents();
// Start the Dear ImGui frame
ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplGlfw_NewFrame();
ImGui::NewFrame();
update();
// Rendering
ImGui::Render();
int display_w, display_h;
glfwGetFramebufferSize(window, &display_w, &display_h);
glViewport(0, 0, 1280, 720);
glClearColor(0.5f,0.5f, 0.5f, 0.5f);
glClear(GL_COLOR_BUFFER_BIT);
ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
// Update and Render additional Platform Windows
// (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
// For this specific demo app we could also call glfwMakeContextCurrent(window) directly)
if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
GLFWwindow* backup_current_context = glfwGetCurrentContext();
ImGui::UpdatePlatformWindows();
ImGui::RenderPlatformWindowsDefault();
glfwMakeContextCurrent(backup_current_context);
}
glfwSwapBuffers(window);
}
}
void AppWindow::addMouseCallBack(GLFWmousebuttonfun action)
{
glfwSetMouseButtonCallback(window, action);
}
void AppWindow::addKeyCallBack(GLFWkeyfun action)
{
glfwSetKeyCallback(window, action);
}
my main method:
int main(int , char**) {
AppWindow window("My app", 1280, 720);
window.run();
return 0;
}
AppWindow.h:
#pragma once
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "imgui.h"
class AppWindow
{
public:
ImVec4 BgColour = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
ImGuiIO io;
GLFWwindow* window;
void (*updateFunction)() = nullptr;
AppWindow(const char* title, int width, int height);
~AppWindow();
void setUpdateFunction(void (*updateFunction)());
void update();
void run();
void addMouseCallBack(GLFWmousebuttonfun action);
void addKeyCallBack(GLFWkeyfun action);
here is an image of my folder structure: my folder structure
here is the imgui files I copied over: imgui files
my include directory contains: Desktop\ImgGUIApps\LearningImGUI\ImGUIwithOpenGL\imguiDependencies Desktop\ImgGUIApps\LearningImGUI\ImGUIwithOpenGL\Libraries\include
my library directory: Desktop\ImgGUIApps\LearningImGUI\ImGUIwithOpenGL\Libraries\lib
additonal dependencies: glfw3.lib
I figured out that this occurs due to a memory access violation in this portion of code as it runs:
glViewport(0, 0, 1280, 720);
glClearColor(0.5f,0.5f, 0.5f, 0.5f);
glClear(GL_COLOR_BUFFER_BIT);
commenting that out just gives me a non-crashing black screen.
I suspect that this may be due to me installing opengl and glfw and imgui incorrectly.
I also don't think that it is because my window variable is being freed, as i declared it in the class declaration.
Okay, so i had to simply write:
gladLoadGL();
after
glfwMakeContextCurrent(window);
I don't remember seeing it in tutorials, or maybe I wasn't paying attention. Anyhow, thanks to @G.M. for making the solution clear to me.