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I was playing Golden Axe for the SMS and it has a hell of a lot of things on the screen, all at the same vertical level (ie: all things were on or near the same horizontal line). No flicker. Why not? I love flicker! At least it has slowdown. Games like Alex Kidd: The Lost Stars has maybe two small things on the same horizontal line and everything on the screen practically disappears.

The same goes for Space Harrier. Why does everything have colored tiles drawn around them? Is the game just redrawing the background again and again and only using sprites for Harrier himself and his gunshots? I'm sure everyone would agree that the game would be much, much better with tiny little sprites and a ton of flicker.

In Space Harrier, everything (except the player) is done in tiles, even the shots (by memory). With only one thing per tile, you get those gaps. If you want flicker: try Space Harrier 3D without the glasses.

You mean background tiles? So basically the entire screen is the background redrawn again and again? I've seen the shots flicker, I think, so they've gotta be sprites.

Space Harrier 3D jitters, not flickers. :P

Just press F11 and/or Alt+F11 in Meka to see what's a sprite (flicker needed) and what's a tile (no flicker, 8px jumps). See the attachments below.

Space Harrier [50 & 60 Hz] (01).png (3.18 KB)

Space Harrier (tiles and sprites)

Space Harrier [50 & 60 Hz] (02).png (716 B)

Space Harrier (sprites only)

Space Harrier [50 & 60 Hz] (03).png (2.76 KB)

Space Harrier (tiles only)

So nobody has figured out why Golden Axe doesn't flicker?

Also Meka doesn't seem to work on my W2K setup past the BIOS screen.

Same reason as Space Harrier, many SMS games used this method to display more stuff on screen (like the boards/columns etc. on the two side of Outrun say for example), the drawbacks are:
1. The movement is choppy, since the tiles are all placed in a 8 pixel per unit (I think) grid.
2. There'll be squares of flat colours surrounding the "sprites" (see Space Harrier screenshots), since they replaced the original bg tiles in those positions.

Joe Redifer wrote

So nobody has figured out why Golden Axe doesn't flicker?

Maxim already explained it. The game draws characters using the background rather than sprites. Flicker is caused by sprite limitations, the background has no such limits.

No, he explained Space Harrier. There are no squares of color surrounding any of the characters in Golden Axe. I would have tried his trick with Meka, but it doesn't want to load any games.

Joe Redifer wrote

No, he explained Space Harrier. There are no squares of color surrounding any of the characters in Golden Axe. I would have tried his trick with Meka, but it doesn't want to load any games.

The way moving obejcts (that aren't sprites) are composited with the background can be done two ways. Space Harrier uses the fast way where the objects replace the background, so you get gaps between the two along the edges. It's pretty ugly.

Golden Axe and some later games combine the existing background graphics with the object so you get filled in edges, and it doesn't look distorted. It's a more complex technique, but can be used quite effectively.

The Mortal Kombat series uses this to an extreme degree, one player is a sprite and the other is a background which is merged in with the actual level background so there aren't any gaps.

Joe Redifer wrote

The same goes for Space Harrier.

You said it yourself :) As Charles said, Golden Axe is merging the background too, but that just makes it slower and thus less can change on-screen at any time.

It's worth mentioning a third option for "large unflickering sprites", which is what Phantasy Star uses for the enemies: any 8x8 tile that is 100% filled by the enemy is drawn as a background tile, and the rest (ie. the edges) are drawn using sprites. It still only gives the ability to move the enemy in blocks of 8 pixels, but then Phantasy Star's enemies don't move at all.

For completeness, I'll mention the last option, which is to draw the enemy entirely using the background tiles, and make the "actual" background totally blank. Then the game can scroll the entire background, and it just looks like the enemy (usually a boss) is moving. See Wonder Boy III, Astro Warrior, etc.

I didn't know the SMS could manipulate the BG so fast. Another mystery solved. Only one more remains, and I shall create a thread. :)

Wow, what a great topic. Good question and excellent replies.
I too love to know about all of this stuff. I had no idea about the tiles being used as sprites. You guys know everything.

Author	Message
Joe Redifer Joined: 11 Sep 2006 Posts: 94 Location: Denver, CO	Why doesn't Golden Axe flicker? Posted: Sun Oct 15, 2006 5:58 am
	I was playing Golden Axe for the SMS and it has a hell of a lot of things on the screen, all at the same vertical level (ie: all things were on or near the same horizontal line). No flicker. Why not? I love flicker! At least it has slowdown. Games like Alex Kidd: The Lost Stars has maybe two small things on the same horizontal line and everything on the screen practically disappears. The same goes for Space Harrier. Why does everything have colored tiles drawn around them? Is the game just redrawing the background again and again and only using sprites for Harrier himself and his gunshots? I'm sure everyone would agree that the game would be much, much better with tiny little sprites and a ton of flicker.

MadMikeAU Joined: 21 Nov 2005 Posts: 150 Location: Sydney, NSW, Australia	Posted: Sun Oct 15, 2006 8:32 am
	In Space Harrier, everything (except the player) is done in tiles, even the shots (by memory). With only one thing per tile, you get those gaps. If you want flicker: try Space Harrier 3D without the glasses.

Joe Redifer Joined: 11 Sep 2006 Posts: 94 Location: Denver, CO	Posted: Sun Oct 15, 2006 9:32 am
	You mean background tiles? So basically the entire screen is the background redrawn again and again? I've seen the shots flicker, I think, so they've gotta be sprites. Space Harrier 3D jitters, not flickers. :P

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Sun Oct 15, 2006 12:37 pm
	Just press F11 and/or Alt+F11 in Meka to see what's a sprite (flicker needed) and what's a tile (no flicker, 8px jumps). See the attachments below. Space Harrier [50 & 60 Hz] (01).png (3.18 KB) Space Harrier (tiles and sprites) Space Harrier [50 & 60 Hz] (02).png (716 B) Space Harrier (sprites only) Space Harrier [50 & 60 Hz] (03).png (2.76 KB) Space Harrier (tiles only)

Joe Redifer Joined: 11 Sep 2006 Posts: 94 Location: Denver, CO	Posted: Wed Oct 18, 2006 12:58 am
	So nobody has figured out why Golden Axe doesn't flicker? Also Meka doesn't seem to work on my W2K setup past the BIOS screen.

Gilbot Guest	Posted: Wed Oct 18, 2006 1:37 am
Gilbot Guest	Same reason as Space Harrier, many SMS games used this method to display more stuff on screen (like the boards/columns etc. on the two side of Outrun say for example), the drawbacks are: 1. The movement is choppy, since the tiles are all placed in a 8 pixel per unit (I think) grid. 2. There'll be squares of flat colours surrounding the "sprites" (see Space Harrier screenshots), since they replaced the original bg tiles in those positions.

Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	Posted: Wed Oct 18, 2006 1:38 am
Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	Joe Redifer wrote So nobody has figured out why Golden Axe doesn't flicker? Maxim already explained it. The game draws characters using the background rather than sprites. Flicker is caused by sprite limitations, the background has no such limits.

Joe Redifer Joined: 11 Sep 2006 Posts: 94 Location: Denver, CO	Posted: Wed Oct 18, 2006 3:08 am
	No, he explained Space Harrier. There are no squares of color surrounding any of the characters in Golden Axe. I would have tried his trick with Meka, but it doesn't want to load any games.

Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	Posted: Wed Oct 18, 2006 3:39 am
Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	Joe Redifer wrote No, he explained Space Harrier. There are no squares of color surrounding any of the characters in Golden Axe. I would have tried his trick with Meka, but it doesn't want to load any games. The way moving obejcts (that aren't sprites) are composited with the background can be done two ways. Space Harrier uses the fast way where the objects replace the background, so you get gaps between the two along the edges. It's pretty ugly. Golden Axe and some later games combine the existing background graphics with the object so you get filled in edges, and it doesn't look distorted. It's a more complex technique, but can be used quite effectively. The Mortal Kombat series uses this to an extreme degree, one player is a sprite and the other is a background which is merged in with the actual level background so there aren't any gaps.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Wed Oct 18, 2006 8:07 am
	Joe Redifer wrote The same goes for Space Harrier. You said it yourself :) As Charles said, Golden Axe is merging the background too, but that just makes it slower and thus less can change on-screen at any time. It's worth mentioning a third option for "large unflickering sprites", which is what Phantasy Star uses for the enemies: any 8x8 tile that is 100% filled by the enemy is drawn as a background tile, and the rest (ie. the edges) are drawn using sprites. It still only gives the ability to move the enemy in blocks of 8 pixels, but then Phantasy Star's enemies don't move at all. For completeness, I'll mention the last option, which is to draw the enemy entirely using the background tiles, and make the "actual" background totally blank. Then the game can scroll the entire background, and it just looks like the enemy (usually a boss) is moving. See Wonder Boy III, Astro Warrior, etc.

Joe Redifer Joined: 11 Sep 2006 Posts: 94 Location: Denver, CO	Posted: Wed Oct 18, 2006 9:36 am
	I didn't know the SMS could manipulate the BG so fast. Another mystery solved. Only one more remains, and I shall create a thread. :)

D Joined: 01 Apr 2005 Posts: 252 Location: Almere, The Netherlands	Posted: Mon Nov 06, 2006 1:41 pm
	Wow, what a great topic. Good question and excellent replies. I too love to know about all of this stuff. I had no idea about the tiles being used as sprites. You guys know everything.

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