Styjun

I'm writing a simple game to discover Vulkan. I'm using GLFW 3 to create the window and handle input. I wanted some basic control over my camera with keyboard input, and I'm observing some strange lag when releasing a key passed the repeat delay.

I use glfwPollEvents() once in my update loop, and set up a key callback :

void Keyboard::key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)

 static size_t count;
 count++;
 if(action == GLFW_PRESS)
 
 std::cout << "(" << count << ") PRESS >> scancode : " << scancode << " 
 if(action == GLFW_REPEAT)
 
 std::cout << "(" << count << ") REPEAT >> scancode : " << scancode << " 
 if (action == GLFW_RELEASE)
 keycode : " << key << std::endl;
 

When running the application, I'm pressing the space bar once, keeping it pressed for some time and releasing it once. (the space bar isn't important here, the results are the same with other keys).

I would expect something like that :

(1) PRESS >> scancode : 65 | keycode : 32
(2) REPEAT >> scancode : 65 | keycode : 32
(3) REPEAT >> scancode : 65 | keycode : 32
// more REPEAT lines
(18) REPEAT >> scancode : 65 | keycode : 32
(19) REPEAT >> scancode : 65 | keycode : 32
(20) RELEASE >> scancode : 65 | keycode : 32

But in fact I get this :

(1) PRESS >> scancode : 65 | keycode : 32
(2) REPEAT >> scancode : 65 | keycode : 32
(3) REPEAT >> scancode : 65 | keycode : 32
// more REPEAT lines
(18) REPEAT >> scancode : 65 | keycode : 32
(19) REPEAT >> scancode : 65 | keycode : 32
(20) RELEASE >> scancode : 65 | keycode : 32
(21) PRESS >> scancode : 65 | keycode : 32
(22) REPEAT >> scancode : 65 | keycode : 32
(23) REPEAT >> scancode : 65 | keycode : 32
(24) REPEAT >> scancode : 65 | keycode : 32
(25) RELEASE >> scancode : 65 | keycode : 32

I get REPEAT events after the initial RELEASE event (which happens when I effectively release the space bar), and I get an extra PRESS and an extra RELEASE event. The longer I press the space bar, the more extra REPEAT I get, but I get only one extra PRESS and one extra RELEASE. If I don't get passed the repetition delay set up in my OS, I get only one PRESS and one RELEASE.

I'm looking for an explanation and/or a workaround, but I don't really know where to go from here. Reading GLFW documentation regarding input handling didn't help, I didn't find anyone with the same problem either.