GLFW window not rendering close button? - c++

My GLFW window renders but the title bar does not render like it does in the tutorial I am following.
I am using fedora on wayland.
Here is the code :
#include <GLFW/glfw3.h>
int main(void) {
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit()) return -1;
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window) {
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window)) {
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_TRIANGLES);
glVertex2f(-0.5f, -0.5f);
glVertex2f(0.0f, 0.5f);
glVertex2f(0.5f, -0.5f);
glEnd();
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glfwTerminate();
return 0;
}
the output is here:
https://imgur.com/a/3kE94OI

Related

Why do i have to call gladLoadGL() after glfwMakeContextCurrent()?

Hello it took me two days to figure out why my window always closed instand.
It was because i called gladLoadGL(glfwGetProcAddress) before glfwMakeContextCurrent(window).
This does NOT work:
int main() {
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
gladLoadGL(glfwGetProcAddress);
GLFWwindow * window = glfwCreateWindow(600, 600, "agag", NULL, NULL);
glfwMakeContextCurrent(window);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(0.2f, 0.5f, 0.6f, 1);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
}
But when i call gladLoadGL(glfwGetProcAddress); AFTER glfwMakeContextCurrent(window); it DOES work!
Do i have load glad everytime i am switching the window? (maybe later i have to)
But is it really like that or is it a bug?
When i write it before glfwMakeContextCurrent the error:
-1073741819 (0xC0000005)
comes up.

Why is OpenGL GLFW Rendering shapes not working?

I am trying to get started with openGL and GLFW in c++. My expectation is that the following code will simply render a square on the screen, but I just get a black screen.
The actual setup is working though, because if I add glClearColor(0.1f, 0.4f, 0.8f, 1.0f);, I do indeed get a blue screen. But what is wrong with my use of GL_QUADS?
#include <iostream>
// GLEW
#define GLEW_STATIC
#include <GL/glew.h>
//GLFW
#include <GLFW/glfw3.h>
const GLint WIDTH = 800, HEIGHT = 600;
int main() {
glfwInit();
glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint( GLFW_RESIZABLE, GL_TRUE);
GLFWwindow *window = glfwCreateWindow(WIDTH, HEIGHT, "Isosurface Stuffing", nullptr, nullptr);
int screenWidth, screenHeight;
glfwGetFramebufferSize(window, &screenWidth, &screenHeight);
if (window == nullptr) {
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glewExperimental = GL_TRUE;
if (GLEW_OK != glewInit()) {
std::cout << "Failed to create GLEW" << std::endl;
return -1;
}
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glViewport(0, 0, screenWidth, screenHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f, screenWidth, 0.0f, screenHeight, 0.0f, 1.0f);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity();
glfwPollEvents();
glColor3f(0.5f, 0.5f, 0.5f);
glBegin(GL_QUADS);
glVertex2f(100, 100);
glVertex2f(200, 100);
glVertex2f(200, 200);
glVertex2f(100, 200);
glEnd();
glfwSwapBuffers(window);
}
glfwTerminate();
return 0;
}
You cannot use the legacy fixed-function pipeline instructions (glBegin, glEnd, glVertex2f, glMatrixMode, glLoadIdentity, glOrtho) in a Core profile OpenGL context (GLFW_OPENGL_CORE_PROFILE). You have to use Compatibility profile OpenGL Context:
glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_COMPAT_PROFILE);
If your system does not allow you to create a compatibility profile context (e.g. Mac), you must use either an OpenGL 2.0 context or a modern OpenGL with Shaders and Vertex Array Objects. A nice tutorial for that is LearnOpenGL

Why is my opengl triangle code producing a black screen?

#include <iostream>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
int main(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
return -1;
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glewExperimental = true;
glewInit();
while (!glfwWindowShouldClose(window))
{
glClearColor(1.0f, 0.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
std::cout << glGetError() << std::endl;
glBegin(GL_TRIANGLES);
glVertex2f(-0.5f, -0.5f);
glVertex2f(0.5f, -0.5f);
glVertex2f(0.0f, 0.5f);
glEnd();
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
Despite setting glClearColor, only a black screen is shown. Drawing the triangle doesn't work either, and glGetError returns 0 everywhere. What am I doing wrong?
(I know this is a legacy way to render a triangle, I'm just trying to test if opengl is working, and apparently, it isn't.)
You cannot use the legacy OpenGL (glBegin/glEnd sequences) with a Core profile OpenGL Context (GLFW_OPENGL_CORE_PROFILE) you must use a Compatibility profile OpenGL context (GLFW_OPENGL_COMPAT_PROFILE):
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_COMPAT_PROFILE);

glClearColor is ignored

I am trying to set the background color to blue, but glClearColor is completely ignored.
Code:
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
GLFWwindow* window = glfwCreateWindow(640, 480, "3D Shooter", NULL, NULL);
glClearColor(0.5f, 0.5f, 1.0f, 1.0f);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT);
glfwSwapBuffers(window);
glfwPollEvents();
}
You seem to be missing a
glfwMakeContextCurrent(window);
https://www.glfw.org/docs/3.3/quick.html

Window not closing GLFW

I am writing a game engine in OpenGL and GLFW. However, somehow my window can't be closed. I tried many things but it doesn't have effect. What's wrong with my code?
I can't find the wrong thing in it - everything seems fine to me.
Code:
int running;
GLFWwindow* window;
Window::~Window()
{
glfwTerminate();
}
Window::Window(int width, int height, const std::string& title)
: m_width(width),
m_height(height),
m_title(title){
glfwInit();
if (!glfwInit())
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
window = glfwCreateWindow(height, width, __FILE__, NULL, NULL);
if (!window) {
glfwTerminate();
}
running = true;
}
void Window::MainLoop()
{
do
{
glfwMakeContextCurrent(window);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glFlush();
glfwPollEvents();
Draw();
glfwSwapBuffers(window);
}
while(running);
}
void Window::Draw()
{
glBegin(GL_TRIANGLES);
glVertex3f( 0.0f, 1.0f, 0.0f);
glVertex3f( 1.0f,-1.0f, 0.0f);
glVertex3f(-1.0f,-1.0f, 0.0f);
glEnd();
}
Thanks!
There are several things but the issue seems to be that you never set running = false.
Try making your while condition looking like this while(!glfwWindowShouldClose(window));
Also if you would like to be able to close the window by pressing escape this should work: while(!glfwWindowShouldClose(window) && glfwGetKey(window_, GLFW_KEY_ESCAPE) != GLFW_PRESS);
Also consider making your int running a bool.
And things such as glfwMakeContextCurrent(window); and glClearColor(0.2f, 0.3f, 0.3f, 1.0f); do not need to be inside your loop if you do not intend to change them.
For more information about openGL and to gain some basic understanding and working examples consider reading https://learnopengl.com/.