Hi @stephengold

I was doing some tests with the new version of lwjgl3.4, apparently there is a small problem, this conflict is related to Wayland, when a window position is set, the JME3 application breaks.

oct. 24, 2024 8:28:08 P. M. com.jme3.system.JmeDesktopSystem initialize
INFORMACIÓN: Running on jMonkeyEngine 3.8.0-SNAPSHOT
 * Branch: unknown
 * Git Hash: 
 * Build Date: 2024-10-24
oct. 24, 2024 8:28:08 P. M. com.jme3.app.LegacyApplication handleError
GRAVE: Wayland: The platform does not support setting the window position
java.lang.Exception: Wayland: The platform does not support setting the window position
	at com.jme3.system.lwjgl.LwjglWindow$1.invoke(LwjglWindow.java:236)
	at org.lwjgl.glfw.GLFWErrorCallbackI.callback(GLFWErrorCallbackI.java:43)
	at org.lwjgl.system.JNI.invokePV(Native Method)
	at org.lwjgl.glfw.GLFW.glfwSetWindowPos(GLFW.java:2536)
	at com.jme3.system.lwjgl.LwjglWindow.createContext(LwjglWindow.java:327)
	at com.jme3.system.lwjgl.LwjglWindow.initInThread(LwjglWindow.java:591)
	at com.jme3.system.lwjgl.LwjglWindow.run(LwjglWindow.java:714)
	at java.base/java.lang.Thread.run(Thread.java:840)

oct. 24, 2024 8:28:08 P. M. com.jme3.system.lwjgl.LwjglContext printContextInitInfo
INFORMACIÓN: LWJGL 3.3.4+7 context running on thread jME3 Main
 * Graphics Adapter: GLFW 3.5.0 Wayland X11 GLX Null EGL OSMesa monotonic shared
oct. 24, 2024 8:28:09 P. M. com.jme3.renderer.opengl.GLRenderer loadCapabilitiesCommon

According to lwjgl, this is incompatible with Wayland (apparently the previous version used x11 as the backend by default).
source: here

This leaves wayland users with a serious problem. Would wayland users have to manually configure the lwjgl backend from now on?

Test Code

import com.jme3.app.SimpleApplication;
import com.jme3.system.AppSettings;

public class JME3 extends SimpleApplication {

    public static void main(String[] args){
        JME3 app = new JME3();
        AppSettings settings = new AppSettings(true);
        settings.setCenterWindow(true);

        app.setShowSettings(false);
        app.start();
    }

    @Override
    public void simpleInitApp() {
    }
}

[ NOTE ]
I don't know if this is the right place to discuss this problem, I hope I don't bother anyone.

@JNightRider Thanks for pointing out this issue. Totally the right place to discuss it. And thanks for the test code.

@JNightRider quick question: Do stable releases of JME work with the Wayland platform, or only with X11?

Current versions 3.x.x-stable with lwjgl3.x < v3.4 work as they use the x11 backend (as long as we use XWayland as a bridge), however with the fixes in the new version of lwjgl jme3 no longer works in wayland...

If no window position is set it works without problems.

I see at least 3 options:

1. Proceed with the LWJGL update even though it will cause some apps to crash on Wayland platforms.
2. Update and add code to catch the exception on Wayland platforms.
3. Delay the LWJGL update until LWJGL v3.3.5 is released, in the hope it will solve the issue.

Seeing as Spasi closed lwjgl3 issue 998 as "3rd party", I have little confidence in option 3.

Seeing as Spasi closed lwjgl3 issue 998 as "3rd party", I have little confidence in option 3.

Option 3 is certainly not reliable

Update and add code to catch the exception on Wayland platforms.

I would like jme3 to continue working with wayland even though it doesn't support viewport positioning.

The problem is in the glfwSetWindowPos() method (class -> LwjglWindow - Line [327 - 333]), if jme3 is removed it works (I think something similar to this can be handled for wayland only)

I can move (drag) the window without problems

@JNightRider:

if jme3 is removed it works

I don't understand what that means. Can you elaborate? Or provide a patch?

@stephengold I'm sorry for not explaining myself correctly...

If we avoided calling the glfwSetWindowPos() method when starting the context, the problem with wayland would not arise, of course this leaves wayland users without the option of positioning the window.

At the moment I can run jme3 if I add this small patch in the LwjglWindow class:

        if (!settings.isFullscreen() && glfwGetPlatform() != GLFW_PLATFORM_WAYLAND) {
            if (settings.getCenterWindow()) {
                // Center the window
                glfwSetWindowPos(window,
                        (videoMode.width() - requestWidth) / 2,
                        (videoMode.height() - requestHeight) / 2);
            } else {
                glfwSetWindowPos(window,
                        settings.getWindowXPosition(),
                        settings.getWindowYPosition());
            }
        }

glfwGetPlatform() != GLFW_PLATFORM_WAYLAND <- patch

Test class

I am using this class as a test, I can drag the window, resize and there is no problem (full screen is not a problem):

import com.jme3.app.SimpleApplication;
import com.jme3.material.Material;
import com.jme3.math.ColorRGBA;
import com.jme3.scene.Geometry;
import com.jme3.scene.shape.Box;
import com.jme3.system.AppSettings;

public class JME3 extends SimpleApplication {

    public static void main(String[] args){
        JME3 app = new JME3();
        AppSettings settings = new AppSettings(true);
        settings.setResizable(true);

        app.setShowSettings(false);
        app.setPauseOnLostFocus(false);
        app.setSettings(settings);
        app.start();
    }

    @Override
    public void simpleInitApp() {
        inputManager.setCursorVisible(true);
        getFlyByCamera().setDragToRotate(true);

        Box b = new Box(1, 1, 1);
        Geometry geom = new Geometry("Box", b);
        Material mat = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
        mat.setColor("Color", ColorRGBA.Blue);

        geom.setMaterial(mat);
        rootNode.attachChild(geom);
    }
}

It seems that this is not a lwjgl specific problem, in the same GLFW documentation it is indicated that this option is not supported on the wayland platform.

I like your patch. It seems more clear than simply catching the exception. I'll add it to this PR.

@JNightRider I'm unable to install Wayland for testing. Would you test this branch please?

Would you test this branch please?

@stephengold Everything works very well, I have not found any errors!

It's great that jme3 works with Wayland ❤️.

Great! Then I believe this is ready for integration.

One thing that came to mind, https://www.glfw.org/docs/latest/news.html.

Window hints for initial window position

GLFW now provides the GLFW_POSITION_X and GLFW_POSITION_Y window hints for specifying the initial position of the window. This removes the need to create a hidden window, move it and then show it. The default value of these hints is GLFW_ANY_POSITION, which selects the previous behavior.

For more information see Window position.

The above comes with this version now, so would it be possible to use these and have the feature work on Wayland?

On the more detailed documentation it says that the windowing system may also ignore these. So I don't know is it exactly the same as old, but sounds more simpler the way it works too.
https://www.glfw.org/docs/latest/window_guide.html#GLFW_POSITION_X
https://www.glfw.org/docs/latest/window_guide.html#window_pos

Hi @tonihele, thank you very much for the suggestion

thanks to @tonihele for suggesting this alternative

GLFW_POSITION_X and GLFW_POSITION_Y: This is definitely a better solution for sales positioning, however it is still incompatible with Waylanda (it doesn't break jme3, it just ignores window positioning). That is to say with wayland it has no effect, it is fine and it would avoid the small patch (detect the platform)...

I overlooked something in this matter, now I have something else to report, setting icons in the window throws a serious error (related to wayland -> compatibility issues).

little suggestion

We can use glfwWindowHint(GLFW_POSITION_X, xPos); and glfwWindowHint(GLFW_POSITION_Y, yPos); methods to set the window position and avoid patching (I didn't try them on Windows or x11, if it works on wayland -> It has no effect but does not throw any error, it is like an alternative to the patch):

if (!settings.isFullscreen()) {
    if (settings.getCenterWindow()) {
        // Center the window
        glfwWindowHint(GLFW_POSITION_X,  (videoMode.width() - requestWidth) / 2);
        glfwWindowHint(GLFW_POSITION_Y, (videoMode.height() - requestHeight) / 2);
    } else {
        glfwWindowHint(GLFW_POSITION_X,  settings.getWindowXPosition());
        glfwWindowHint(GLFW_POSITION_Y, settings.getWindowYPosition());
    }
}

With icons, I think we have to patch it to avoid calling the glfwSetWindowIcon(window, icon); method and breaking jme in wayland.

protected void setWindowIcon(final AppSettings settings) {
    if (glfwGetPlatform() == GLFW_PLATFORM_WAYLAND) {
        return;
    }
    ...
}

Of course now there is no support for custom icons and sales positioning on platforms with wayland, I think this is fine since JME3 works with wayland (I don't want to port my small games to another engine or switch to x11 just for that).

I will perform more tests when you have time to avoid unexpected surprises.

I was recently testing things with this branch, I can run jme3 on wayland without problems (except for the 2 known issues)