Zandronum open gl problems

I see the occasional white speckle in OpenGL mode but nothing like that. What video card are you using, when was the driver last updated and are you running Zandronum at the monitor's native resolution.

There's also a support forum where you might find an answer.

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Such "sparkles" are typically the result of numerical imprecision during the transfer of map geometry to the GPU, or, during later rasterization. Usually this happens when one attempts to draw geometry whose vertices meet with a T-junction.

In order to ensure contiguous sampling results during frame rasterization it is usually necessary to eliminate such T-junctions by adding an additional vertex with the exact same coordinates.

At one time the GZDoom renderer would only do such splitting if the render mode was set to "quality" and not when set to "fast". As Zandronum uses (an older version of) the GZDoom renderer you could see if it has a similar option.

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DaniJ said:

As Zandronum uses (an older version of) the GZDoom renderer you could see if it has a similar option.

It has, and I see some sparkles on the "speed" setting but they're fewer and further away than the OP's screenshot.

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The option's still in GZDoom. Options->Display Options->OpenGL Options->Preferences->Rendering Quality

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GreyGhost said:

...I see some sparkles on the "speed" setting but they're fewer and further away than the OP's screenshot.

This is dependent on various factors; video card, driver, resolution, etc...

However, if GZDoom renderer does all the necessary splitting correctly, the difference between "speed" and "quality" should be "some" or "none".

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The "Speed" setting does not add any intermediate vertices. That's the main reason it even exists. On older NVidia cards it made no visual difference but unfortunately these days "Quality" is basically necessary to get glitch-free rendering.

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Just working on a similar OpenGL problem in DoomLegacy last night.
It appears the generation of polygons for OpenGL has some problems.
1. The polygon vertexes do not always match the wad vertex locations.
2. The polygon generation may make two vertexes where the wad had one.
This leaves a little gap between the textures.
3. Not all the segs are in the polygons. Some get left out.
Some different between zennode and bsp will change this, but not in any obvious way.
4. The polygons are slightly different than the Doom drawing.
The slight mismatch in vertex location makes the jaggies at the edge slightly different (for adjacent texture panels), and then there occurs jaggie gaps (sparkles).

On my new freedoom map01, Zennode creates a nodemap where the polygon routine misses one seg, which results in a missing panel draw.
Using bsp instead fixes that missing panel, but the debugging stmts say it has three segs that are not in polygons.

I assume most of this is similar in Zandronum ..

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wesleyjohnson said:

I assume most of this is similar in Zandronum ..


Definitely not. Zandronum, like GZDoom, requires the presence of GL nodes. If none are provided they get created when the map starts.

Normal nodes are not really that good for GL rendering, thanks to their vertex imprecisions.

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Thanks DaniJ, when I switched the option from speed to quality it completely got rid of those annoying white specks.

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Oh, it samed happened in my older laptop. It wasnt affected the gameplay much.

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