Pattern color limitation question

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By kanageddaamen

Rookie (25)

kanageddaamen's picture

10-08-2016, 18:23

Hello all,

I am currently working on a new project and just started looking into the graphics capabilities of Screen 4. It was my understanding that for this mode, 8x8 patterns were limited to 2 colors per horizontal line. However, while investigating some graphics of games from the era, I came across the following from "Vampire Killer":

If you look at the square sections of brown brick patterns, it certainly seems that they are using 4 colors per line (white, brown, dark gray and black on the 2nd horizontal line)

Does anyone know how this was done?

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By ARTRAG

Enlighted (6240)

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10-08-2016, 19:00

This is screen 5, that is full bitmap mode with 16 colors freely accessible in the Whole screen.
The blocky aspect is due to the fact the game is using 8x8 tiles, but they are moved by software using VDP copy commands. Screen 5 does not support any kind of tile at HW level.

By kanageddaamen

Rookie (25)

kanageddaamen's picture

10-08-2016, 19:08

Interesting. This seems like an inefficient method for a game of this generation to me.

By ARTRAG

Enlighted (6240)

ARTRAG's picture

10-08-2016, 20:01

The vdp copy commands are fast enough to develop games with flip screen (as vampire killer is) or coarse scrolling (look e.g. at sd snatcher).
The vdp is much less suitable for smooth scrolling games, and it is not a casualty that the best examples avoid screen 5 (look e.g. at space manbow).
Nevertheless some remarkable exceptions of games with fine scrolling in bitmap mode exist (look e.g. at manbow 2)

By kanageddaamen

Rookie (25)

kanageddaamen's picture

10-08-2016, 20:14

So the net-net is the majority of games that required smooth scrolling used tiled modes for their graphics and implemented software scrolling for horizontal scrolls (save for on the MSX2+?)

By Lord_Zett

Paladin (807)

Lord_Zett's picture

10-08-2016, 20:14

and screen 4 is not 2 colors fr 8*8 but 2 colors per line of a 8*8. so you have on sc4 the possibility of putting 16 colors in 1 tile

By PingPong

Prophet (3437)

PingPong's picture

11-08-2016, 14:22

Msx 2 smooth scrolling.
Vertical scroling. No problem in any mode reg 24 allows circular smooth scrolling .
Horizonal scrolling . There is no support. Scrolling should be done by brute force.
If you want smooth scroll you van achieve thid easily on sc4 because you move the nametable 768 bytes by blitting to vram.
On screen5 not feasible be ause you move the bitmap 24k bytes.
Artrag is the master in achieving smooth horz scrolling in s reen 5 and 8!
Ask him but basically you use r18 to scroll pixel by pixel the screen and on a hidden page you build the screen scrolled by 8 or 16 pixels issuing vdp command that build the scrolled screen as stripes each time you move one pixel right or left using r18
After 8 or 16pixel you have built the entire screen and you swap the hidden page then reset r18 to originAl
Then the entire cy le restart
Search on youtube uridium msx2

By Manuel

Ascended (15695)

Manuel's picture

11-08-2016, 14:34

Why you say there is no support for horizontal smooth scrolling and that brute force is needed, and later you mention r18 hor scrolling?

By PingPong

Prophet (3437)

PingPong's picture

11-08-2016, 19:50

The v9938 r18 is meant to adjuat the screen.
Only v9958 has good support for scrolling with border masking and circular offset
The use of r18 is tricky

By DarkSchneider

Paladin (862)

DarkSchneider's picture

16-08-2016, 12:45

R#18 is not really scroll support. You have to build the whole screen buffer (brute force) instead only the new part, but in this case are only a 768 byte matrix (some more really but approx).

By hit9918

Prophet (2866)

hit9918's picture

16-08-2016, 17:05

on screen 4 it is 768 bytes but on screen 8 it is some 48k bytes.
the set adjust divides the workload by 16, the last rescue for screen 5 screen 8 scroll.

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