Nebulus' 'precise hidden surface removal'

dreamkatcha · 20 March 2020, 07:34

In the manual for the various versions of Nebulus it proudly exclaims the implementation of "Rotational 3D scrolling with precise hidden-surface removal running at 25 frames per second, and multi-layer parallax scrolling on underwater levels at 50 frames per second."

Hidden-surface removal?

Coagulus · 20 March 2020, 08:31

Im assuming it's when the steps go around the side?

dreamkatcha · 20 March 2020, 21:34

I dunno. If you remove a hidden surface (even if it's done precisely), how would anyone know anything had changed? It sounds like a running gag from Catch-22 to me. :|

ruinashiro · 25 March 2020, 04:54

It removes the surfaces that won't be seen so they don't have to be drawn, speeding up the process by only drawing (or rendering in the case where there is actually something 3d happening here) what the player can see.

dreamkatcha · 25 March 2020, 10:26

Ah, now I get it, thanks. So a technically impressive trick used to deliver the rotating tower effect, although something that goes on in the background that wouldn't even occur to the player unless they knew about coding. That's where I was lost - I was expecting to be able to actually see some change or other on screen.

DanScott · 25 March 2020, 10:40

seems to me it can just be done with a couple of compares.. nothing technically impressive really

commodorejohn · 25 March 2020, 15:16

They're taking the piss. No way is it actually doing 3D math of any kind, when you can far more easily just draw a 2D representation of brick lines scrolling across a rectangular area and cycle it with the player position.

roondar · 25 March 2020, 16:11

I always thought it was just a cleverly designed animation. Note that they also have the same game running on much less powerful hardware and it still runs great, which makes me suspect it's animation all the more.

Does anyone know for sure?

saimon69 · 26 March 2020, 03:22

More than animation is z-stacking with double buffering imo

gimbal · 28 March 2020, 12:21

I ran into this coding secrets video about Mickey Mania which actually has a rotating tower inspired by Nebulus in it. The video shows some of the tricks to get the tower to work, quite interesting.

[ Show youtube player ]

commodorejohn · 28 March 2020, 18:50

Hah, nice breakdown.

saimon69 · 28 March 2020, 20:52

The mickey mania tower has the addition of angled steps compared to the static blocks of nebulus, though; i suspect the c64 one is even smaller in footprint

20 March 2020, 07:34	#1
dreamkatcha I've got a new byline Join Date: Mar 2002 Location: Manchester, UK Posts: 1,219	Nebulus' 'precise hidden surface removal' In the manual for the various versions of Nebulus it proudly exclaims the implementation of "Rotational 3D scrolling with precise hidden-surface removal running at 25 frames per second, and multi-layer parallax scrolling on underwater levels at 50 frames per second." Hidden-surface removal?

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20 March 2020, 08:31	#2
Coagulus Gets there in the end... Join Date: Sep 2005 Location: Wales Posts: 863	Im assuming it's when the steps go around the side?

20 March 2020, 21:34	#3
dreamkatcha I've got a new byline Join Date: Mar 2002 Location: Manchester, UK Posts: 1,219	I dunno. If you remove a hidden surface (even if it's done precisely), how would anyone know anything had changed? It sounds like a running gag from Catch-22 to me. :\|

25 March 2020, 04:54	#4
ruinashiro Registered User Join Date: Jan 2017 Location: Tokyo, Japan Posts: 51	It removes the surfaces that won't be seen so they don't have to be drawn, speeding up the process by only drawing (or rendering in the case where there is actually something 3d happening here) what the player can see.

25 March 2020, 10:26	#5
dreamkatcha I've got a new byline Join Date: Mar 2002 Location: Manchester, UK Posts: 1,219	Ah, now I get it, thanks. So a technically impressive trick used to deliver the rotating tower effect, although something that goes on in the background that wouldn't even occur to the player unless they knew about coding. That's where I was lost - I was expecting to be able to actually see some change or other on screen.

25 March 2020, 10:40	#6
DanScott Lemon. / Core Design Join Date: Mar 2016 Location: Tier 5 Posts: 1,212	seems to me it can just be done with a couple of compares.. nothing technically impressive really

25 March 2020, 15:16	#7
commodorejohn Shameless recidivist Join Date: Jun 2012 Location: Duluth, Minnesota (USA) Age: 38 Posts: 262	They're taking the piss. No way is it actually doing 3D math of any kind, when you can far more easily just draw a 2D representation of brick lines scrolling across a rectangular area and cycle it with the player position.

25 March 2020, 16:11	#8
roondar Registered User Join Date: Jul 2015 Location: The Netherlands Posts: 3,420	I always thought it was just a cleverly designed animation. Note that they also have the same game running on much less powerful hardware and it still runs great, which makes me suspect it's animation all the more. Does anyone know for sure?

26 March 2020, 03:22	#9
saimon69 J.M.D - Bedroom Musician Join Date: Apr 2014 Location: los angeles,ca Posts: 3,540	More than animation is z-stacking with double buffering imo

28 March 2020, 12:21	#10
gimbal cheeky scoundrel Join Date: Nov 2004 Location: Spijkenisse/Netherlands Age: 42 Posts: 6,926	I ran into this coding secrets video about Mickey Mania which actually has a rotating tower inspired by Nebulus in it. The video shows some of the tricks to get the tower to work, quite interesting. [ Show youtube player ]

28 March 2020, 18:50	#11
commodorejohn Shameless recidivist Join Date: Jun 2012 Location: Duluth, Minnesota (USA) Age: 38 Posts: 262	Hah, nice breakdown.

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28 March 2020, 20:52	#12
saimon69 J.M.D - Bedroom Musician Join Date: Apr 2014 Location: los angeles,ca Posts: 3,540	The mickey mania tower has the addition of angled steps compared to the static blocks of nebulus, though; i suspect the c64 one is even smaller in footprint