I have just started to learn about the OpenGL API using https://www.learnopengl.com/ and was using the code from the Hello Window tutorial to open a new GLFW window. However, something is not quite right as the console opens up immediately when executed but the window takes 2 seconds to open. Using the Visual Studio debugger I have found that glfwCreateWindow() seems to be the culprit but no information seems to exist on why it is slow for me.
The code goes as follows:
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
void processInput(GLFWwindow* window);
void framebufferSizeCallback(GLFWwindow* window, int width, int height);
int main()
{
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGL Test", nullptr, nullptr); //This line takes 2 seconds to execute
if (window == nullptr)
{
std::cout << "Failed to instantiate GLFW window!" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebufferSizeCallback);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialise GLAD" << std::endl;
return -1;
}
while (!glfwWindowShouldClose(window))
{
processInput(window);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
void processInput(GLFWwindow* window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
{
glfwSetWindowShouldClose(window, true);
}
}
void framebufferSizeCallback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
I am using Visual Studio 2017 and have already tried running in debug and release mode as well as using different GLFW libs but to avail.
Nevermind, it turns out that I had set the preferred graphics processor in the NVIDIA Control Panel to be my GPU rather than auto-select which was causing the program to load in many OpenGL extensions using my GPU and therefore take longer to open the window. After changing the setting, the window opens in a much more reasonable time of 500 milliseconds by using the integrated graphics.
Related
When I started I used the GLFW example 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);
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glfwTerminate();
return 0;
}
When running this it gives me a black screen titled "Hello world" which is exactly what I want. But by simply adding GLAD:
#include <glad/glad.h>
#include <GLFW/glfw3.h>
...and giving window hints:
//Specify the OpenGL versions we're using
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
Suddenly it tells me the window failed to initialize.
But by simply adding this:
#ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
...it allows the window to initialize but crashes when glClear(GL_COLOR_BUFFER_BIT) is called and it gives me the error
'./Voxel\ Game' terminated by signal SIGSEGV (Address boundary error)
I know this because when I remove that line it works, it just doesn't clear the screen.
This is the full code I have now in case the error is somewhere else in there:
#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#define SCREEN_WIDTH 640
#define SCREEN_HIEGHT 480
int main()
{
GLFWwindow* window;
//Initialize the library
if (!glfwInit())
{
std::cout << "Failed to initalize GLFW" << std::endl;
return -1;
}
//Specify the OpenGL versions we're using
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
//Create a windowed mode window and its OpenGL context
window = glfwCreateWindow(SCREEN_WIDTH, SCREEN_HIEGHT, "Voxel Game", NULL, NULL);
if (!window)
{
std::cout << "Failed create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
//Make the window's context current
glfwMakeContextCurrent(window);
//Loop until the user closes the window
while (!glfwWindowShouldClose(window))
{
//Render here
//glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
//Swap front and back buffers
glfwSwapBuffers(window);
//Poll for and process events
glfwPollEvents();
}
glfwTerminate();
return 0;
}
You are not initializing glad, add gladLoadGL(glfwGetProcAddress); after glfwMakeContextCurrent() and check it returns OK.
In general, there is no OpenGL library apart from some old OpenGL1.1 stuff (in Windows at least), all those GL calls are implemented in the graphics drivers directly, GLAD library just defines a lot of function pointers and wraps them in nicer macros. Then during initialization, it will dynamically load the functions from the drivers present on the machine. Hence the need to generate GLAD for specific OpenGL version.
So if you get segfaults on some GL calls, a good guess is some of those functions were not found, maybe because they are not supported on the HW or because you did not setup GLAD/GLFW correctly.
I'm trying to change the background color in a window generated by OpenGL/GLFW and I'm using a similar code than the one in the GLFW docs. I'm on Ubuntu 20.04 and the window background is always black, no matter the parameters in the glClearColor() function.
I tried this on Windows 10 using VS and it worked perfectly, but on Ubuntu it's not working at all. No error messages are generated.
I also followed The Cherno's Sparky game engine series, and tried encapsulating the glClear() function in a class method, but this didn't change anything.
This is the whole code:
#include <iostream>
#include <GL/gl.h>
#include <GLFW/glfw3.h>
int main(int argc, char *argv[])
{
std::cout << "Hello world!" << std::endl;
if (!glfwInit())
{
// Initialization failed
exit(EXIT_FAILURE);
}
GLFWwindow* window = glfwCreateWindow(640, 480, "My Title", NULL, NULL);
if (!window)
{
// Window or OpenGL context creation failed
std::cout << "Error creating window!" << std::endl;
glfwTerminate();
exit(EXIT_FAILURE);
}
glfwMakeContextCurrent(window);
glfwSwapInterval(1);
glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
while (!glfwWindowShouldClose(window))
{
int width, height;
glfwGetFramebufferSize(window, &width, &height);
glViewport(0, 0, width, height);
glClear(GL_COLOR_BUFFER_BIT);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwDestroyWindow(window);
glfwTerminate();
exit(EXIT_SUCCESS);
return 0;
}
I'm supposed to get a window with a red background but it's black.
As additional elements, I'm also using CMake to help configuring and building the project (quite overkill I know), and I believe clang is the compiler used for the project. Maybe that influences the result.
You need an appropriate loader after glfwMakeContextCurrent(window).
If you are using glad, you should call gladLoadGL(glfwGetProcAddress) after glfwMakeContextCurrent(window) as the official doc suggests here.
I have created a simple OpenGL program, following the LearnOpenGL tutorial. It just creates a window and fills it with a color. I am using Visual Studio 2019.
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
int main() {
// Initialize GLFW
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
// Create GLFW Window
GLFWwindow* window = glfwCreateWindow(800, 600, "Golden Retriever", NULL, NULL);
if (window == NULL) {
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
// Initialize GLAD
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
// Render Loop
while (!glfwWindowShouldClose(window)) {
processInput(window);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
glViewport(0, 0, width, height);
}
void processInput(GLFWwindow* window) {
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
The program works perfectly, however it uses way too much CPU (around 50%). Is it something in Visual Studio properties, or am i just doing something wrong in my code?
You can enable vsync with glfwSwapInterval(1)
The way Windows measures CPU time falls flat on its face for processes that spend most of their time blocking (=waiting) on kernel calls. What happens in your case is, that in order to V-Sync your program has to wait for the vertical retrace to happen. That usually involves waiting for a synchronization object that's locked from kernel context.d
In order to make Windows measure consumed CPU time accurately add a Sleep(1) right before the buffer swap call.
I tried doing OpenGL using GLFW. I was beginning to make a window
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
int main() {
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(500, 500, "Test", NULL, NULL);
if (window == NULL) {
std::cout << "GLAD failed.";
}
glfwMakeContextCurrent(window);
void frameBufferSizeCallback(GLFWwindow* window,int width,int height);
glfwSetFramebufferSizeCallback(window, frameBufferSizeCallback);
glViewport(0, 0, 500, 500);//Error here
while (!glfwWindowShouldClose(window)) {
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
void frameBufferSizeCallback(GLFWwindow* window,int width,int height) {
glViewport(0,0,width,height);
}
I get some error saying Exception thrown at 0x00000000 in OpenGLTest0.exe: 0xC0000005: Access violation executing location 0x00000000. And the window I created doesn't even respond to anything including Task Manager "end task. I was using Visual Studio 2017 and had to "end task" the whole aplication in order to remove the window. Also I am on Windows 10.
Could somebody tell me where I am wrong? I thank you in advance!
You need to initalize the glad library, without that it can't load in the function pointers.
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
I use MinGW compiler and Code::Blocks IDE, 16.01.
I have interested in graphic library OpenGL. I've started to find articles and found one.
I've set up glew, freeglut and glfw by myself without using cMaker. Then, I've decided to link libraries into the project. So, I have the following sequence in Linker settings:
C:\MinGW\lib\glew\glew32s.lib
C:\MinGW\lib\freeglut\libfreeglut.a
C:\MinGW\lib\freeglut\libfreeglut_static.a
C:\MinGW\lib\glfw\libglfw3dll.a
C:\MinGW\lib\glfw\libglfw3.a
Following by this tutorial (in russian language) I've written in linker settings glew32s.lib (with 's'), 'cause it's a static library and I need this one. After that I've tried to compile but get these errors:
C:\MinGW\lib\glew\glew32s.lib(tmp\glew_static\Release\Win32\glew.obj):(.text$mn+0x7)||undefined reference to `_imp__wglGetProcAddress#4'|
C:\MinGW\lib\glew\glew32s.lib(tmp\glew_static\Release\Win32\glew.obj):(.text$mn+0x4)||undefined reference to `_imp__wglGetProcAddress#4'|
The code I've tried to compile is:
#include <iostream>
// GLEW
#define GLEW_STATIC
#include <GL/glew.h>
// GLFW
#include <GLFW/glfw3.h>
// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;
// The MAIN function, from here we start the application and run the game loop
int main()
{
std::cout << "Starting GLFW context, OpenGL 3.3" << std::endl;
// Init GLFW
glfwInit();
// Set all the required options for GLFW
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
// Create a GLFWwindow object that we can use for GLFW's functions
GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
if (window == nullptr)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
// Set the required callback functions
glfwSetKeyCallback(window, key_callback);
// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
glewExperimental = GL_TRUE;
// Initialize GLEW to setup the OpenGL Function pointers
if (glewInit() != GLEW_OK)
{
std::cout << "Failed to initialize GLEW" << std::endl;
return -1;
}
// Define the viewport dimensions
int width, height;
glfwGetFramebufferSize(window, &width, &height);
glViewport(0, 0, width, height);
// Game loop
while (!glfwWindowShouldClose(window))
{
// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
glfwPollEvents();
// Render
// Clear the colorbuffer
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// Swap the screen buffers
glfwSwapBuffers(window);
}
// Terminate GLFW, clearing any resources allocated by GLFW.
glfwTerminate();
return 0;
}
// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
std::cout << key << std::endl;
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
}
Then I wrote in linker settings glew32.lib (without 's'), comment glewExperimental = GL_TRUE; line and try again.
The program was compiled successfully. It was run and the result was as it must be.
But I want to use a static library instead of dynamic. How can it be solved?
I guess that library 'glew32s.lib' is built with Visual studio. So you cannot link with it unless you change your compiler.
I suggest you get a GLEW library built with MinGW or build one by yourself. Libraries for MinGW are named 'libNAME.a',
Also, dynamic libraries have no limitation on its name, so there could be no difference between static library (instead, they are named, like, libNAME_static.a or libNAMEs.a, ...)