[rcore] Wayland: GLFW framebuffer scale is handled incorrectly

[gfaster]

Please, before submitting a new issue verify and check:

• I tested it on latest raylib version from master branch
• I checked there is no similar issue already reported
• I checked the documentation on the wiki
• My code has no errors or misuse of raylib

Issue description

This is effectively a followup to #4815.

GLFW 4.3 now handles fractional scaling correctly by default, namely changing GLFW_COCOA_RETINA_FRAMEBUFFER to GLFW_SCALE_FRAMEBUFFER and enabling it by default. much of the handling the Raylib to handle when screen size doesn't equal render size is redundant and breaks rendering.

I'm including a workaround that goes back to pre-4.3 behavior. I also wrote a more complete fix, but I don't have the means to test it, so I figured going back to old behavior would be preferable for now.

Environment

OS: NixOS 25.05pre785698.b024ced1aac2 (Warbler)
Kernel: Linux 6.13.11
Display (LG HDR 4K): 3840x2160 @ 60 Hz (as 2259x1271) in 27"
Display (XB271HU): 2560x1440 @ 144 Hz (as 2229x1253) in 27"
WM: KWin (Wayland)
CPU: Intel(R) Core(TM) i7-7700 (8) @ 4.20 GHz
GPU: NVIDIA GeForce RTX 2080 Rev. A

INFO: GL: Supported extensions count: 395
INFO: GL: OpenGL device information:
INFO:     > Vendor:   NVIDIA Corporation
INFO:     > Renderer: NVIDIA GeForce RTX 2080/PCIe/SSE2
INFO:     > Version:  3.3.0 NVIDIA 570.133.07
INFO:     > GLSL:     3.30 NVIDIA via Cg compile

Cmake command:

cmake .. -DUSE_EXTERNAL_GLFW=ON -DBUILD_EXAMPLES=OFF -DCUSTOMIZE_BUILD=ON -DBUILD_SHARED_LIBS=ON

Issue Screenshot

Current behavior is identical to the screenshot in #4815

Code Example

#include "raylib.h"
#include <GLFW/glfw3.h>
#include <stdio.h>

#define RECT_SIZE 100.0f

void
print_info(GLFWwindow *handle)
{
	int glfw_winx, glfw_winy;
	glfwGetWindowSize(handle, &glfw_winx, &glfw_winy);
	printf("GLFW window size:      %d, %d\n", glfw_winx, glfw_winy);

	int glfw_fbx, glfw_fby;
	glfwGetFramebufferSize(handle, &glfw_fbx, &glfw_fby);
	printf("GLFW framebuffer size: %d, %d\n", glfw_fbx, glfw_fby);

	int rl_winx, rl_winy;
	rl_winx = GetScreenWidth();
	rl_winy = GetScreenHeight();
	printf("RL window size:        %d, %d\n", rl_winx, rl_winy);

	int rl_fbx, rl_fby;
	rl_fbx = GetRenderWidth();
	rl_fby = GetRenderHeight();
	printf("RL render size:        %d, %d\n", rl_fbx, rl_fby);

	puts("");
}

void
draw(GLFWwindow *handle)
{
	// Draw a square at each corner of the screen, turning blue if the
	// mouse is over the top left square
	ClearBackground(BLACK);
	Vector2 pos = GetMousePosition();
	Color rcolor = (pos.x < RECT_SIZE && pos.y < RECT_SIZE) ? BLUE : RED;
	Vector2 bot = (Vector2) { (float)GetScreenWidth() - RECT_SIZE, (float)GetScreenHeight() - RECT_SIZE };
	DrawRectangleRec((Rectangle){0.0f, 0.0f, RECT_SIZE, RECT_SIZE}, rcolor);
	DrawRectangleRec((Rectangle){bot.x, 0.0f, RECT_SIZE, RECT_SIZE}, rcolor);
	DrawRectangleRec((Rectangle){bot.x, bot.y, RECT_SIZE, RECT_SIZE}, rcolor);
	DrawRectangleRec((Rectangle){0.0f, bot.y, RECT_SIZE, RECT_SIZE}, rcolor);

	(void)handle;
	// print_info(handle);
}

int
main(void)
{
	glfwInitHint(GLFW_PLATFORM, GLFW_PLATFORM_WAYLAND);

	// SetConfigFlags(FLAG_WINDOW_RESIZABLE | FLAG_MSAA_4X_HINT);
	SetConfigFlags(FLAG_WINDOW_RESIZABLE | FLAG_WINDOW_HIGHDPI | FLAG_MSAA_4X_HINT);
	InitWindow(640, 480, "Issue on Wayland");
	GLFWwindow *handle = glfwGetCurrentContext();
	print_info(handle);
	SetTargetFPS(60);
	while(!WindowShouldClose()) {
		BeginDrawing();
		draw(handle);
		EndDrawing();
	}
}

[raysan5]

much of the handling the Raylib to handle when screen size doesn't equal render size is redundant and breaks rendering.

Definitely, that should be reviewed.

[gfaster]

Via a friend's Mac, it seems like FLAG_WINDOW_HIGHDPI is broken in a similar way on MacOS (seems like not fixed by #4909 ). git-bisect tells us it was broken by 4bed374 -- this should be fixed when GLFW 4.3 behavior is matched

[vegerot]

👋🏼 I recently updated Raylib and my game doesn't work anymore. I'm not sure if this Issue is the right place to report it or if I should open a new Issue.

Steps to reproduce:

1. git clone --recurse-submodules [email protected]:vegerot/snek.git
2. zig build play

This should work!

Now

3. cd raylib && git switch -d 5c954c1f (this is the next commit!)
4. zig build play

Expected: Should also work

Actual: it looks wrong. It's super zoomed in

---

I found two workarounds:

1. Resize the window. If you resize the window, the game will fix itself and look correct
2. In snek.zig:682, set raylib.FLAG_WINDOW_HIGHDPI. This will also make it work correctly

Is this bug related to the current issue, or should I open a new one? My issue was introduced in 5c954c1 which seems related...

[gfaster]

@vegerot I was testing this on a Mac earlier, and it seems that the old behavior was horribly broken. Fundamentally, you should be drawing things according to the window size and not the render size, which is the default behavior for GLFW (and I assume SDL too but I haven't checked). I need to get on fixing this for all platforms and re-aligning with modern GLFW/SDL.

Also, on Mac, you should likely always have HIGHDPI set since the screens are so high resolution. I believe (based on vibes I think?) that not setting the flag is really for outdated windowing systems such as X11 or Windows.