fullscreen mode disables gamma correction

[stephengold]

I've noticed visually that applications with gamma correction enabled look very different in windowed display modes than they do in fullscreen. Visual comparisons suggest this is because gamma correction isn't actually enabled in fullscreen mode.

Seen in both v3.2.4 and v3.3.0-alpha5 of jMonkeyEngine with both v2 and v3 of LWJGL.

[riccardobl]

I can't reproduce this. Maybe there was something wrong in the code you were testing.

[stephengold]

I'll check again.

[stephengold]

I wasn't able to test on Linux due to issue #947. On Windows 7, a simple test with JME 3.3.2-stable and LWJGL 2.9.3 shows noticeable contrast between the viewport background and the stats background:

1. in a 16bpp 640x480 window with isGamma=true
2. in a 16bpp 640x480 fullscreen with isGamma=true
3. in a 16bpp 640x480 fullscreen with isGamma=false

but no contrast (black-and-black) in a 16bpp 640x480 window with isGamma=false.

Here is the test app:

import com.jme3.app.SimpleApplication;
import com.jme3.font.BitmapText;
import com.jme3.math.ColorRGBA;

public class Main extends SimpleApplication {

    public static void main(String[] args) {
        Main app = new Main();
        app.start();
    }

    @Override
    public void simpleInitApp() {
        flyCam.setEnabled(false);
        
        ColorRGBA backgroundColor = new ColorRGBA(0.04f, 0.04f, 0.04f, 1f);
        viewPort.setBackgroundColor(backgroundColor);

        BitmapText statusText = new BitmapText(guiFont, false);
        statusText.setLocalTranslation(0f, cam.getHeight(), 0f);

        String message = 
                "   bpp=" + settings.getBitsPerPixel()
                + "   fullScreen=" + settings.isFullscreen() 
                + "   isGamma=" + settings.isGammaCorrection();
        statusText.setText(message);
        guiNode.attachChild(statusText);
    }
}

[riccardobl]

That's the normal behavior. Writing to an sRGB framebuffer causes the color to be gamma corrected, they will look different unless they are linearized beforehand

        ColorRGBA backgroundColor = new ColorRGBA().setAsSrgb(0.04f, 0.04f, 0.04f, 1f);

Textures are linearized automatically

[stephengold]

I agree that colors should look different between isGamma=true and isGamma=false, but that's not what this issue is about. The issue is that they don't look different in fullscreen, even between isGamma=true and isGamma=false.

[riccardobl]

I can't reproduce...could it be driver specific?
Do you get the same issue even with 24bpp color depth?

[stephengold]

I suppose it could be a driver-specific issue.

I'm not finding any fullscreen modes with 24bpp color depth. However, I reproduced the issue with 32bpp 640x480 fullscreen.

[riccardobl]

Can you try to use native resolution fullscreen with lwjgl3?
Also, what drivers are you using, on which gpu?

[stephengold]

LWJGL 2.9.3 context running on thread jME3 Main
 * Graphics Adapter: nvd3dumx,nvwgf2umx,nvwgf2umx
 * Driver Version: 23.21.13.8873
 * Scaling Factor: 1
OpenGL Renderer Information
 * Vendor: NVIDIA Corporation
 * Renderer: GeForce GT 545/PCIe/SSE2
 * OpenGL Version: 4.6.0 NVIDIA 388.73
 * GLSL Version: 4.60 NVIDIA
 * Profile: Compatibility

I tested with LWJGL3 at the highest available resolutions and found good contrast:

• in a 24 bpp 1914x1049 window with isGamma=true
• in 32 bpp 1920x1080 fullscreen with isGamma=true

but poor contrast (black-and-black):

• in a 24 bpp 1914x1049 window with isGamma=false
• in 32 bpp 1920x1080 fullscreen with isGamma=false

In other words, the issue went away with high resolution and LWJGL3. Okay, that's interesting. Do you have a hypothesis that might explain all this?

[yaRnMcDonuts]

I can confirm I am also experiencing the same issue when trying to run full screen.

Since @riccardobl was unable to reproduce the issue, I should note that my device's GPU is a NvidiaGeForce GTX 1080. I still need to test this on my older device with an AMD but will report back with the results when I do.

[stephengold]

@yaRnMcDonuts any news on this issue?