GLFW: window & contextGLFW 3.0

glfwWindowHint

Sets one option for the NEXT window created with glfwCreateWindow: OpenGL version, profile, MSAA, visibility…

Signature

void glfwWindowHint(int hint, int value);

How it works

glfwCreateWindow has only a few parameters. Everything else is set beforehand with hints: you call glfwWindowHint once per option, then create the window.

Hints stay set for every later window until glfwDefaultWindowHints or glfwTerminate. A hint is a request: if the driver cannot give an OpenGL version you asked for, glfwCreateWindow fails with GLFW_VERSION_UNAVAILABLE instead of silently giving you another one.

Parameters

hintint

Which option to set.

Common values

GLFW_CONTEXT_VERSION_MAJOR / _MINOR: The OpenGL version to create, e.g. 4 and 6 for OpenGL 4.6. macOS stops at 4.1.
GLFW_OPENGL_PROFILE: GLFW_OPENGL_CORE_PROFILE (modern functions only), GLFW_OPENGL_COMPAT_PROFILE (old ones too) or GLFW_OPENGL_ANY_PROFILE.
GLFW_OPENGL_FORWARD_COMPAT: GLFW_TRUE removes everything deprecated. Required on macOS for any core context 3.2 or newer.
GLFW_CONTEXT_DEBUG: GLFW_TRUE asks for a debug context, so glDebugMessageCallback gets detailed messages. Old name: GLFW_OPENGL_DEBUG_CONTEXT.
GLFW_SAMPLES: Samples per pixel for MSAA on the default framebuffer, e.g. 4. Default 0 (off).
GLFW_DEPTH_BITS / GLFW_STENCIL_BITS: Bits of the depth and stencil buffers. Defaults 24 and 8, which is what you want.
GLFW_SRGB_CAPABLE: GLFW_TRUE asks for a framebuffer that can do sRGB conversion (with glEnable(GL_FRAMEBUFFER_SRGB)).
GLFW_RESIZABLE: GLFW_FALSE gives a window the user cannot resize. Default GLFW_TRUE.
GLFW_VISIBLE: GLFW_FALSE creates the window hidden; show it later with glfwShowWindow (e.g. after moving it).
GLFW_POSITION_X / _Y: GLFW 3.4: where the window opens, in screen coordinates. Default GLFW_ANY_POSITION (the system decides).
GLFW_SCALE_TO_MONITOR: GLFW_TRUE grows the window on high-DPI monitors (Windows, X11) so it keeps its apparent size.

valueint

The new value: a number, GLFW_TRUE / GLFW_FALSE, or a constant such as GLFW_OPENGL_CORE_PROFILE.

Tips & pitfalls

Hints must come AFTER glfwInit (which resets them) and BEFORE glfwCreateWindow.
Asking for 4.6 on a machine with only 4.1 (macOS, old GPUs) fails. Ask for the oldest version your code really needs.
String hints (such as the X11 class name) use glfwWindowHintString instead.

Errors

When the call is invalid it does nothing and sets an error, which glGetError returns:

GLFW_NOT_INITIALIZED: Called before glfwInit or after glfwTerminate.
GLFW_INVALID_ENUM: A hint, mode, key or button argument is not a valid GLFW constant.

Example

example.cpp

1glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
2glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
3glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
4#ifdef __APPLE__
5glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);           // macOS: 4.1 at most
6glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE);
7#endif
8glfwWindowHint(GLFW_SAMPLES, 4);                         // 4x MSAA
9GLFWwindow* window = glfwCreateWindow(1280, 720, "Hello", nullptr, nullptr);

Official GLFW documentation