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2.8x, unreliable GL_LINE_SMOOTH / GL_POLYGON_SMOOTH behavior
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Description

For some graphics cards in 2.8x (more information needed), smoothing is ignored. This task is to gather more information and see if it can be resolved.

See: T54723#548752 and replies.


Edit, it seems some graphics cards simply ignore the smooth setting.

Event Timeline

Can confirm anti-alias works fine (and has been since the beginning) in the following setup:

OS: Ubuntu 17.10
Graphics Card: Nvidia GTX 1050
Resolution: 2560x1440
Blender UI Line Width: Auto (picks "Thin")

Lapineige added a subscriber: Lapineige.EditedNov 2 2018, 10:02 AM

It works fine on my setup too.
OS: Ubuntu 18.10
Graphics Card: Nvidia GTX 880m (Nvidia Drivers used)
Resolution: 1920*1080 (17" screen, not HDPi)
Blender UI Line Width: Auto (picks "Thin")

@Campbell Barton (campbellbarton) , this is a misuse of core profile from Blender side. Not sure where exactly this gizmo is being drawn, but from quick grep in the source shows two common mistakes:

  • glLineWidth() with values greater that 1.0. As per specification this INVALID_VALUE.
  • Smooth lines shouldn't be used nowadays either. I cant' find exact spec entry for them, but Khronos lists this as deprecated/removed in the "Common Mistakes" section. But even if it's still part of the spec, the rest of the intenet agrees that quality of smooth lines is rather poor.

I am a strong believer in theory that in 2.8 we should not use deprecated/known-to-behave-bad OpenGL features. With Core profile we've got flexibility of programmable render pipeline, where we can implement smooth line which will be guaranteed to work the way we want on all the hardware.

P.S. Maybe @Clément Foucault (fclem) can drop his knowledge here as well.

glLineWidth() with values greater that 1.0. As per specification this INVALID_VALUE.

Well this is partially true. The values supported are implementation dependent.

Smooth lines shouldn't be used nowadays either. I cant' find exact spec entry for them, but Khronos lists this as deprecated/removed in the "Common Mistakes" section. But even if it's still part of the spec, the rest of the intenet agrees that quality of smooth lines is rather poor.

I was the one who added line smoothing to gizmos because the aliasing caused by wide lines was terrible. So it's better than nothing.

Correctly implementing smooth wide lines needs to have a dedicated shader for it that just mimics the behavior of old GL_LINE_SMOOTH. This shouldn't be too hard but I don't know how feasible it is for 2.80.

As for GL_POLYGON_SMOOTH this is even more tricky. Since it's mostly for UI stuff, I would suggest to just draw alpha blended shapes with manual added geometry on the contours of the shape and just make the outer ring alpha = 0.0 so that vertex color interpolation make some kind of smoothing.

If it is large points that you want to draw (larger than max gl point size), we can make a shader variation that draws a AA point and you just have to submit a quad.

Could we have a general solution for this?

We want add-on authors to be able to make their own gizmos, so if they need to be aware of special shader internals - it could make the API hard to use (maybe this can be hidden from the developer?).

Possible alternatives...

  • Render all gizmos to over-sampled off-screen buffer (advantage of not having artifacts - especially regarding GL_POLYGON_SMOOTH when alpha < 1.0), disadvantage of having to use multi-sample buffer which needs special handling (perhaps this isn't practical if we want to occlude gizmos by other elements in the scene).
  • Don't use GL_LINE_SMOOTH / GL_POLYGON_SMOOTH at all.

    Occasions where we want smoothing have to be handled by each gizmo's drawing code (which can include specialized shader for eg).

    We'll try make them look OK without smoothing (transform looks OK IMHO)... if it's important to do some AA tricks, each gizmo's drawing code can handle that it's self (with policy of not using GL_*_SMOOTH).
Campbell Barton (campbellbarton) lowered the priority of this task from 90 to 50.Nov 7 2018, 3:12 AM
Campbell Barton (campbellbarton) edited a custom field.

Didn't find any other appropriate place to ask this, but what is the proper way to add antialiasing to custom gizmos?
I'm currently writing my own gizmos for addons, but couldn't find any dedicated property to enable or disable the antialiasing. I'm also interested in the way points are drawn in the 3D view, as these can be square or round.

Didn't find any other appropriate place to ask this, but what is the proper way to add antialiasing to custom gizmos?

There isn't a a convenient way to do this at the moment, that's why this task is still open.

I'm currently writing my own gizmos for addons, but couldn't find any dedicated property to enable or disable the antialiasing. I'm also interested in the way points are drawn in the 3D view, as these can be square or round.

Round points are currently drawn as either small circles or using shaders.

Thanks Campbell.
Looking forward for possible solutions on this.

Clément Foucault (fclem) lowered the priority of this task from 50 to Low.

This is really problematic for OSX users on retina display.

Possible workaround is to use a geometry shader variant for every common shader and switch the shader just before drawing if we are drawing a line.
The issue is that if we do that we loose the uniforms configuration because they were changed for another shader. And there is no way to know what type of primitive the shader will be drawn with until the moment the drawcall is issued.

So the real fix would be to change every places that draw thick lines to use a special shader(s) explicitly and pass the line width as uniform.

I wouldn't consider this high priority for 2.80 release as this fix requires some thinking and maybe deeper change.

Is there a chance for a fix anytime soon?

When working in the viewport, I'd agree calling those thin lines a discomfort.
But when you need to create screenshots for printing purposes, this is a real problem...

Do not go together Ubuntu and Macintosh. Please do separate. Only for Macintosh. Do not use Windows, Do not use Ubuntu.

How come this is marked as a LOW priority? The annotations are useless without proper thickness. I’m running Blender 2.81 on Mojave 10.14.6 on a MacBook pro 15” 2018 and the annotations are 1px thick regardless of the line thickness settings.

I am use Macintosh.
Yes I told Blender report ticket many times make me frustrate. Blender 2.79b is perfect but 2.80 and up mess up. They need to fix I ask Blender company again.

Just to give an update, the 2.82 beta will have a fix for wide line in the viewport tomorrow. (See rB014eb69cf858)

This won't fix the issue for transform gizmos, or the UI. So I'll keep the report open. Do note I have plans for fixing it for UI and gizmos but it's not decided when I'll have time to tackle it.

FYI, this still doesn’t work in 2.82 alpha experimental builds (on macOS). Perhaps because the experimental builds are not yet beta?

@Dolphin Dream (dolphindream) Seems to only affect macOS in this case as well. It works properly on Windows and Linux.

Oh well please do it work on MacOS some one who work on Blender 2.8x support DO IT

@Dolphin Dream (dolphindream) I can't see aliasing in your screenshot. Can you double check that your viewport settings (in user preferences) have Overlay Smooth Wires enabled?

Where is "User Preferences" I not see. Everyone use Blender 2.82 Alpha.

The problem is still here with Blender v2.82a and macOS 10.14. It's sad to see such a major UI issue is marked as "low priority".

Any update on this? FYI, drawing errors with GL_LINE_SMOOTH and GL_POLYGON_SMOOTH also affect custom drawing in operators.

After reporting the issue again in a new task, I've been pointed to this task. So i'll briefly reiterate. On macOS:

  • Gizmos are hard to see in the viewport
  • Gizmos lack consistency with every other UI element in the viewport
2.79 on macOS2.83 on macOS2.83 on Windows

I think this a regression since Blender 2.79. Can @Clément Foucault (fclem) or @Campbell Barton (campbellbarton) confirm if this will be addressed for Blender 2.83?

Yes I agree with you. Blender 2.8x need to fix everything I am still wait for Blender developer to fix everything.
I do use MacOS Catalina 10.15.4 beta.
I have low vision I unable to read too thinner line (wire) as well. Please copy from Blender 2.79b to paste to 2.80 so can read thickness wire.

Low priority, this, really?
2.9 alpha and still unusable in OSX :(

@Clément Foucault (fclem)
I am sorry I disagree with you they did not fix yet timeline. I am going show you proof.

I think this task was marked as "Resolved" automatically and should be re-opened.
The problem has only been fixed in some places out of many.

Still getting unusable hairline annotation lines in Blender 2.83LTS on OSX 10.15.5. Other issues regarding this direct to here and this is closed...

@Philip (Amparose) look at Blender 2.90 Alpha let you check.
https://builder.blender.org/download/
You will see. Blender 2.80 is no long to fix only Blender 2.90 Alpha.

@Philip (Amparose)
Blender 2.90 Alpha
Touch enlarge picture you can see.
Look at picture