SW Sprites in screen2

ページ 3/5
1 | 2 | | 4 | 5

By PingPong

Prophet (4093)

PingPong さんの画像

10-07-2011, 19:52

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...

1.5/1 means that vdp is 1.5 slower or faster than the cpu?
what did you have tryed exactly?

By PingPong

Prophet (4093)

PingPong さんの画像

10-07-2011, 19:56

http://www.youtube.com/watch?v=RgcsX4AbQPU show sw sprites in screen5. I do not know however:
1) fps
2) the average size of each sprite
3) the exact handling. It's a page flip trick however.
4) if the vdp works with hw sprites on or off. (Makes a heavy difference)

some screen have a lot of objects

By hit9918

Prophet (2927)

hit9918 さんの画像

10-07-2011, 20:05


@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.

no wait! I meant meant the monochrome sprite is not worth doing.
scrolling yes/no got major impact on how much blitter you got left in screen 5

By hit9918

Prophet (2927)

hit9918 さんの画像

10-07-2011, 20:10

@PingPong

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)

I assumed a copy of the screen in RAM:
1) draw BOBs
2) clean up the mess in one single copy from shadow RAM Smile

By PingPong

Prophet (4093)

PingPong さんの画像

10-07-2011, 20:41

@hit9918: i think vdp is usable with my technique like blade lords do . i've tested the game with openMSX & a tcl script that show the % of time the vdp is executing command in a single frame (something like VDP % usage in a frame) and during the animations, i've seen it does 16x16 logical copy and 18x16 highspeed copy. the % of time is variable with some peak usage but always less than 50%. there where 5 objects on screen. so i can suppose it can reach to 10 objects and more.

By hit9918

Prophet (2927)

hit9918 さんの画像

10-07-2011, 20:47


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

The z80 potential: two pixel in one outi, 9 cycles per pixel on screen 5! blitter was 44 cycles per pixel...

Hey, imagine the big sprites got a non-transparent square core. When you draw such core squares with the cpu, you need none of the RAM consuming things I talked.

Example 32x32 pixel core:

loop:
5	exx
288	16x outi for 32 pixels
5	exx
12	add hl,de ;offset to next line in vram
14	out (c),l
14	out (c),h  ;h got setwrite bit already set. well what about screen 5, me MSX1 coder.
14	djnz loop ;line counter
--
352 cycles

352 cycles / 32 pixel = 11 cycles per pixel including line overhead with vram setup.

While the cpu is running, the blitter could paint the corner parts of the sprites with transparent pixels!

With typically 4 outside frame parts with transparent pixels, you could call the cpu to blit 32x8 pixels 4 times and in parallel launch 4 blits for the frames.

This is ideal for "little amount of very fat BOBs". For small thingies flying around, you still got plenty hardware sprites.

By Paulbrk

Hero (611)

Paulbrk さんの画像

10-07-2011, 20:57

Guys, this post is for screen2 SW sprites, why you talk about screen5? Can you please return to the topic?

Very good reflexions.

I am very interested on SW sprites for MSX1.

By Paulbrk

Hero (611)

Paulbrk さんの画像

10-07-2011, 21:08

What are your thots about the 3 Opera games I have talked before?

By PingPong

Prophet (4093)

PingPong さんの画像

10-07-2011, 21:17

What are your thots about the 3 Opera games I have talked before?

all games got pratically solid background-
a situation a lot easy that a full sw sprite emulation over a mixed background.
one can use predefined tiles and have FAAAASST animation with solid background. just poke the right byte on name table

By hit9918

Prophet (2927)

hit9918 さんの画像

10-07-2011, 21:22

@PingPong:

I always had some ZX 64x64 pixel monster BOB game in mind. Now Blade Lords looks easy.

blitter HMMM 2784 byte per NTSC frame, makes 10.5 cycles per pixel.
blitter LMMM 976 bytes per NTSC frame, makes 61 cycles per pixel.

The game got sprites, this time I take sprites on and 212 line screen.

So with one single copy to clean up from a backup page, we are at 71.5 cycles per pixel.
Makes 832 pixel per NTSC frame, makes 3.25 16x16 sprites. oops. Tongue

To get the framerate of the youtube video: you get amazing 32 sprites! at 6 frames per second Tongue
Looks like BOB games work by framerate trading.

ページ 3/5
1 | 2 | | 4 | 5