Colecovision Jittery Scrolling

[polyex]

This is kind of a technical question, so perhaps a programmer can shed some light. Why is the scrolling on the Colecovision so jerky? Zaxxon jumps to mind, but there are other examples too. It's like the background is moving too many pixels at a time. It's pretty far from the smooth look of the  arcade and even other platforms. 

[Serguei2]

Colecovision does not have scrolling hardware.

 

The only way to scroll is to move tiles.

 

Tile has 8x8 pixels. 

 

That's why scrolling games need to move 8 pixels at the time.

[CrazyBoss]

Its possible to have "bit scrolling" smooth scrolling, but mentioned no hardware support for that at the ColecoVision VDP.

 

A few games/demos from the Colecovision/MSX world.

 

 

 

 

 

 

 

[Tursi]

As noted above, there's no hardware in the Coleco VDP for smooth scrolling - and all the graphics modes are based on 8x8 tiles. Smooth scrolling is usually accomplished by pre-defining all the shifted tiles and having them ready to go. This takes a lot of memory - it means you need to define two tiles for each onscreen one - and then do it 8 times for single pixel scrolling - so that's 16 characters for one 8x8 pattern. Then, since it needs to straddle two characters, you also need the characters that can be placed beside it.

 

Other options are scrolling more than one pixel at a time, or uploading changed patterns to the VDP every frame. But the VDP is too slow to update EVERY pattern in one frame, so there's still usually some compromise.

 

The Magellan tool (for making game maps) has the ability to analyze the map and output the characters you need for smooth scroll.

 

 

Thread is getting pretty long, towards the end it got a new home, so the latest version is not in the first post there.

 

[nanochess]

Princess Quest

 

Mecha-8

 

Mecha-9

 

 

 

[youki]

In other style : Battle of Hoth

 

BTW: Malaika is impressive for the MSX 1

 

Lotus F3 , makes me think to the excellent Burning Rubber on Colecovision:

 

 

 

[Pixelboy]

2 hours ago, youki said:

Lotus F3 , makes me think to the excellent Burning Rubber on Colecovision:

Actually, Burn Rubber is a sort of "reskin" of Lotus F3. Both games are from the same guys. 

Edited June 13, 2020 by Pixelboy

[artrag]

Uridium ported to colecovision 

Uridium on YouTube

 

Edited June 20, 2020 by artrag

[insertclevernamehere]

As far as original run games go, Nova Blast by Imagic seems to scroll smoothly.

[artrag]

Uridium uses a specific VDP configuration that doubles the number of tiles usable for the scrolling.

The whole level, under any offset, uses 1024 tiles and they are all loaded in VRAM, so only name table is updated