0000520: OpenGL: Firing projectiles directly up/down makes sprite invisibile

Notes
(0001926) Torr Samaho (administrator) 2011-07-23 12:50	That's the same in GZDoom, right?

(0001930) Xenaero (reporter) 2011-07-23 17:43	It appears so. I cannot test with sprite billboarding as GZDoom does not support such a feature as I can find. Due to this, sprites aren't even visible at that angle. I did test with it prior to posting but I can not confirm it's a GZDoom renderer issue or a sprite billboarding issue.

(0001931) Edward-san (developer) 2011-07-23 18:34	Did you check "Options"->"Display Options"->"OpenGL Options"->"Preferences" ? There's the sprite billboarding x/y.

(0001933) Xenaero (reporter) 2011-07-23 20:33 edited on: 2011-07-23 20:35	I had not had the most updated version of GZDoom. It appears the issue is present in GZDoom as well, identical even. I assume this is an issue I must take up with the developers? Having attached two images, straight up aiming, no sprites will display, albeit particles are not affected. Slightly adjust the angle downwards from the maximum above angle and sprites will show. Interesting?

(0001937) Torr Samaho (administrator) 2011-07-24 00:40 edited on: 2011-07-24 19:46	Yes, this is something that should be fixed in GZDoom first. I vaguely remember this issue though. Probably Graf already commented on this in the past.

(0001946) Gez (reporter) 2011-07-24 19:40	It's pretty much not a bug. Sprites are vertical 2D objects. If you look at their "side", since they have no third dimension, they are perfectly flat and therefore invisible. This image shows what happens at an extreme angle; it should be easy to understand from it why a 90° angle results in invisible sprites with the default Y-billboarding. Note that XY-billboarding avoids the invisibility issue, but doesn't necessarily look better for it, and also suffers from clipping bugs in the presence of translucent 3D floors.

(0001948) Edward-san (developer) 2011-07-24 21:39	Isn't this weird? From what I see in the image you posted, the XY billboarding should let you see the sprite no matter what inclination (the sprite will be obviously wrong, though), the Y billboarding behaviour is ok. Just a curiosity: what happens if you fire a rocket up, then pause it, go up the rocket and see it down?

(0001949) Xenaero (reporter) 2011-07-24 23:49	> Note that XY-billboarding avoids the invisibility issue. It doesn't. That's the problem.

(0009052) Watermelon (developer) 2014-06-11 16:07	Is this fixed in gzdoom?

(0009091) Frits (reporter) 2014-06-11 18:35	nope, still happens in the latest build of gzdoom.

(0022169) Xenaero (reporter) 2022-03-27 22:04	As of GZDoom 4.7.1 the issue is resolved. Tested in both their Vulkan and OpenGL renderers. The explosion is still wacky but you see the rocket.

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Issue History
Date Modified	Username	Field	Change
2011-07-21 19:24	Xenaero	New Issue
2011-07-23 12:50	Torr Samaho	Note Added: 0001926
2011-07-23 12:50	Torr Samaho	Status	new => feedback
2011-07-23 17:43	Xenaero	Note Added: 0001930
2011-07-23 17:43	Xenaero	Status	feedback => new
2011-07-23 18:34	Edward-san	Note Added: 0001931
2011-07-23 20:33	Xenaero	Note Added: 0001933
2011-07-23 20:34	Xenaero	File Added: Screenshot_Doom_20110723_163212.png
2011-07-23 20:34	Xenaero	File Added: Screenshot_Doom_20110723_163242.png
2011-07-23 20:35	Xenaero	Note Edited: 0001933	View Revisions
2011-07-24 00:40	Torr Samaho	Note Added: 0001937
2011-07-24 00:40	Torr Samaho	Status	new => feedback
2011-07-24 19:40	Gez	Note Added: 0001946
2011-07-24 19:46	Torr Samaho	Note Edited: 0001937	View Revisions
2011-07-24 21:39	Edward-san	Note Added: 0001948
2011-07-24 23:49	Xenaero	Note Added: 0001949
2011-07-24 23:49	Xenaero	Status	feedback => new
2012-06-09 13:22	Torr Samaho	Category	General => Bug
2014-06-11 16:07	Watermelon	Note Added: 0009052
2014-06-11 16:07	Watermelon	Status	new => feedback
2014-06-11 18:35	Frits	Note Added: 0009091
2022-03-27 22:04	Xenaero	Note Added: 0022169
2022-03-27 22:04	Xenaero	Status	feedback => new

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