MSX VS Spectrum 3D graphics.

Champion (311)

27-02-2014, 17:12

This video is for people that think that MSX has very slow video drawing, this is a comparison between the game on MSX and Spectrum (OpenMSX & Spectaculator) Freescape game can be converted to MSX, I am sure they run more or less like Spectrum.Comparison betwen MSX & Spectrum drawing 3D solid poligons

By msxegor

Master (183)

28-02-2014, 07:55

Well,
MSX may look slower because on spectrum you just draw on display memory, but in ported games on MSX you draw in some memory buffer and later you have to copy buffer to VRAM. On the other hand Spectrum has to slow-down Z80 when it accesses display memory. Overall performance may be equal. MSX2 can draw filled triangles really fast

By ARTRAG

Enlighted (6935)

28-02-2014, 08:54

Few trivial consideration about filled polygons in 3d graphic: a monochrome screen 2 picture fits in 6K where the same picture in screen 5 needs 24K.
For filled polygons in screen 5, even assuming z80 and vdp filling polygons in parallel (it will never happen all the time), as the vdp is as fast as the z80, you will get in general 1/2 of the frame rate you would get in screen 2 with monochrome pictures.
I would expect a totally different result for wire frame graphic where only lines have to be plotted and the vdp can really make the difference.
For wire frame graphic, provided that in screen 2 and screen 5 the number of lines and their lengths are the same, only in screen 5 cpu and vdp can go in parallel doubling (theoretically) the frame rate.
Anyway I would ask Microtech about real bottlenecks and actual limits as his work is probably the state of art on 3d graphic and rendering on msx

By Timmy

Master (200)

28-02-2014, 11:50

It's interesting to see that you're demonstrating the speed differences of a fast action game between the machines to prove that Freescape games can be converted to the MSX.

Freescape games are notorious about their framerates. Although there are parts that can be moved fast, sometimes they could have very low framerates like 1 frame per second, or even less. "They run more or less like Spectrum", as you called it, could mean turning a 1 frame per second game into a 1 frame per 2 seconds game.

All of these speed talk is a bit pointless anyway, as these games are mostly about really slow adventuring, and secondly, you don't have to port them to the msx1 nowadays.

By tonigalvez

Champion (311)

28-02-2014, 12:01

Timmy, It seems you talk without knowing how wonderfull freescape games are. And the most important, the use of 3D construction Kit.

Artrag, take acount of half of the screen, not the entire screen, this simulator use half of the screen.

When you use a MSX2+(at 6Mhz) or Turbo-R with r800 activated, this games can have much better framerate.
Consider the posibility of draw the poligons on wireframe.

By Daemos

Prophet (2065)

28-02-2014, 16:21

Quote:

When you use a MSX2+(at 6Mhz) or Turbo-R with r800 activated, this games can have much better framerate.
Consider the posibility of draw the poligons on wireframe.

There are some problems with that you have to use some serious tricks to overcome the speed penalty you get in R800 mode when outing to VDP. If your conversion depends strongly on CPU speed then this might get you somewhere. The bottleneck is in the VDP however which gets even worse in R800 mode

By hit9918

Prophet (2932)

28-02-2014, 17:38

Quote:

They run more or less like Spectrum", as you called it, could mean turning a 1 frame per second game into a 1 frame per 2 seconds game.

No, the copy to screen is a constant work.
Copy halve a screen mono takes 0.025 seconds.
The heavy game at 1fps: so then the thing would take 1.025 seconds instead 1 second.
Just 2.5% difference, that is nothing.

By hit9918

Prophet (2932)

28-02-2014, 18:46

@Daemos, if I remember right, the bios call to switch cpu mode does not much more than push pop all registers.
Such thing can be afforded two times per frame.
Especialy when z80 mode does the vram jobs so much faster.
Just check timings out with changing border color.

By hit9918

Prophet (2932)

28-02-2014, 18:48

For action games with less number of polygons, maybe again the MSX way would be a charset way like with scrollers.
Those parts of a polygon that are 8x8 pixels blank could go by drawing just 1 byte in the nametable!
The complicated part is in the polygon borders. In the end not faster than ZX, but with color.

ARTRAGs charset movie player shows the potential:
http://www.youtube.com/watch?v=2up41-p091k&t=3m10s

Ever seen such hires 16 colors anywhere else?
The ZX could not even display it as a still picture. Its attributes cant take random color combinations.

By hit9918

Prophet (2932)

28-02-2014, 19:06

And similar to the MSX1 idea of 1 nametable byte changing 8x8 pixels,
a TurboR engine could have "if 16x16 pixels are blank, then make a nice fast blitter fill".
TurboR has the cpu power to deal such logic in RAM and then benefit from optimized VDP acess.

By Daemos

Prophet (2065)

28-02-2014, 19:18

If you can prepare as many of the data with the R800 ahead you save a lot of time to send commands to the VDP. In Z80 mode you can send these commands in the fastest way possible. You can then even go faster by 1.) have a lot of data prepared in the VRAM and use a command to copy it to the buffer 2.) use outing during the command processing to load data from the ram into VRAM.