SW Sprites in screen2

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By MsxKun

Paragon (1115)

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10-07-2011, 14:41

I would say... check Knight Lore for MSX2 Big smile

http://www.youtube.com/watch?v=mL2wwosBxbs

By Paulbrk

Hero (611)

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10-07-2011, 14:51

Please load this games on your MSX:

Livingstone Supongo MSX1
Goody MSX1
Last Mission MSX1

You can see that the main character is a sprite, some enemies are sprites and some not, the this you fire on this games are SW sprites, for example, on Livingstone Supongo, when you trow a knife or a grenade, if passes thru the plants or any other background element, you can see that it goes behind, not in front, and some color clash (very little and very good done). And, you can see that the grenade has two colors. On the splash screen, the main character uses the pole vault, you can see some color clash with the background.

I do not know how Opera do, but is with colors and is fast, please consider that games like a reference of the SW sprites.

Hannibal

By hit9918

Prophet (2927)

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10-07-2011, 16:03


does not allow me to go more than 5-6 sprites x frame @50hz.

@PingPong, I am surprised. I think of the blitter bandwidth "roughly like outi".
That would be like 18 cycles per byte for save and restore. Would be 9 cycles per pixel.
And the read-modify-write needs 18 cycles * 1.5.

9 * 2 + 18 * 1.5 = 45 cycles per pixel.
I had figures like "259 cycles per line" i.e. per 16 pixel, means 16 cycles per pixel ooops.

It looks plausible, the reason is every cpu op does 8 pixels.

By the way I assumed that there is no save of the background, in one copy I repair things from a shadow buffer that must hold a copy of the screen. But this doesn't change the situation.

Generally screen 5 games are a lot more nicer than ZX games.
On the other hand, in the category "biggest BOBs", the monochrome ZX is the 8bit master.
And ZX style on MSX seems to overtake the blitter.

By jltursan

Prophet (2619)

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10-07-2011, 16:39

About blitter bandwith, some time ago I roughly measured a speed relation of 1.5/1 (VDP/CPU). This was in screen 8 and using a standard CPU speed of 3.58Mhz; but I suposse that the VDP speed is the same despite the mode.

In "Caverns of Titan" also used a lot of smooth SW sprites; but hey, they're a bunch of tricks; so it's not a good example of what brute force can do...

By hit9918

Prophet (2927)

hit9918의 아바타

10-07-2011, 17:41


So teoretically, every zx speccy game, that does not have scrolling, but instead only manage sw sprites, can be ported in screen 5 at greater speed?
Still not so sure...

@PingPong: I feel if the game is without scrolling, it may not be worth doing.

To get the cpu version without overheads, you got to write a hairy engine. And let's say you end up being 1.5 times faster than the blitter. I think I would prefere the 1.5 times slower screen 5 game in screaming 16 colors over the ZX style.

With scrolling, the argument is that blitter is full with copy burden, while in screen 2 scrolling can be done in the nametable (green beret did that).

But, thinking further, I would prefere the 128 pixel wide MSX2 hardware sprite monster on a ultra screamin 256 colors background to a monochrome game Wink

Is there maybe a youtube video of the style of the game you got in mind?

By hit9918

Prophet (2927)

hit9918의 아바타

10-07-2011, 18:00

Looking at a Knightlore which seems to screen 8, I just wonder.

MSX Assembly page says: "These values are valid for ALL screens from 5 to 12 ". So when the transparent pixel blit needs a per-pixel-mode, then it is same speed on screen 8 as on screen 5!

The transparent blit dominates when doing BOB cleanup with just one single blit from a shadow copy of the screen. So BOBs on screen 8 are barely slower.

By MsxKun

Paragon (1115)

MsxKun의 아바타

10-07-2011, 18:36

Looking at a Knightlore which seems to screen 8, I just wonder.

It is Screen 5 Big smile

By hit9918

Prophet (2927)

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10-07-2011, 19:12

LMMM does 1344 bytes per NTSC frame with a blank screen.
With LMMM, pixels per frame is same as bytes per frame.

Result is 44 cycles per pixel. Surprising numbers.

By hit9918

Prophet (2927)

hit9918의 아바타

10-07-2011, 19:21

Looking at a Knightlore which seems to screen 8, I just wonder.

It is Screen 5 Big smile

Big smile Then Knightlore deserves a palette award.

By PingPong

Prophet (4093)

PingPong의 아바타

10-07-2011, 19:38


@PingPong: I feel if the game is without scrolling, it may not be worth doing.

@hit9918:
why not? even a game without scroll can be nice in 16 color mode.


To get the cpu version without overheads, you got to write a hairy engine. And let's say you end up being 1.5 times faster than the blitter.

@hit9918:
Umh, calculations are somewhere not correct.
for a standard sw sprite one need those operations:
1) background save: i consider this speed to a 'normalized' value of 1
2) sprite plotting, with TPSET logical operation. VDP is 2.9 times slower than (1)
3) background restore: same time than (1)

So a complete cycle lasts for:

1+2.9+1=4.9. round to 5. Now, the vdp can move on screen 5 @50hz with sprites enabled and 256x192 active area about 180000 bytes/sec. Every sprite is 128 bytes.
Every single operation is 5 times the amount of bytes the vdp is able to move in a sec.
so the number of sprites that vdp can handle in a second is: (180000/128)/5=281.
in a 50 hz frame we have 281/50=5.6 sprites per frame.

Can the z80 do the same, without being totally bound to gfx? I think the blitter in this situation can help a lot.

what are your calculations or assumptions?

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