Why is the Jaguar bad at texture mapping?

[CrazyChris]

I know I've heard this before, but I can't remember? From a hardware standpoint why is the Jaguar not good at texture mapping? Please elaborate.

 

Chris

[Atari_Owl]

Because it is unable to do texmapping in phrase mode (64bit) and must do it in pixel mode unless the copy is a straight 1-1 copy (which in tex mapping is very rarely the case)

 

In addition, since there must be a read for texture data as well as the pixel write, and since the ram is arranged in row/column pages, there is a page fault delay when texture and destination are not almost adjacent in ram.

 

All this

1. Pixel mode not phrase mode (.25*speed)

2. Additional read

3. Additional page miss

 

Makes texmapping a LOT slower than gouraud

[justclaws]

Hello,

 

In addition, since there must be a read for texture data as well as the pixel write, and since the ram is arranged in row/column pages, there is a page fault delay when texture and destination are not almost adjacent in ram.

 

This explanation was really good. To clarify more though, for Chris,

could I just add that normally (e.g. on a PC 3D graphics card) the

graphics card has local RAM (as the GPU does) and so the texture

is stored in that RAM, and required no read from main memory.

 

If the blitter had had local RAM (e.g. 4K) then it could have been

a different story, even with pixel mode writes, because the data

for the textures would not have involved an external read + miss.

 

The blitter does have a pattern register, but unless you want to

create VERY boring textures, it's no help. The real purpose of the

pattern register of course is to clear or fill RAM with known data.

 

Cheers,

JustClaws.

[DracIsBack]

Also, for a layman's explanation ...

 

in 1993, Texture Mapping was a relatively "new" feature in consoles.

[Bryan]

Texture mapping requires fast access to RAM (textures), and the Jag's RAM is the slowest part of the system.

 

-Bry

[Atari_Owl]

JaguarII was intended to have both local Texture ROM (a few generic textures) and RAM (i think) to speed up tex mapping.

 

And as Drac said, texmapping was pretty new in '93. Even Wolfenstein was very new and radical.

[Gunstar]

Also, for a layman's explanation ...

 

in 1993, Texture Mapping was a relatively "new" feature in consoles.

 

..and the Jaguar was one of the first consoles (it and the 3DO)that was made for any kind of fast 3D (at the time), the 16-bitters needed added hardware to even come close to what the Jaguar could do (e.g. Genesis VR racing with SH1 chip in cart, SNES with the FX/FX2 chips in carts; StarFox. So, the designers put more thought into the then state-of-the art gauraud shading and light-sourcing, and less into texturemapping since it wasn't widely used then, even on the PC. The hardware of the Jag would have been capable, but Atari's stinginess with ram became it's undoing when compared to other next gen systems that had more extensive texturemapping hardware AND memory for it. The Blitter is a fantastic Processor, but no memory to take advantage properly.

 

I think Atari didn't think the Next Generation consoles would be using 3D polygons with Texturemapping as extensively as they did; in the past consoles had always basically been a generation behind computers, and i think they thought it would be that way again. But it turned out that since Atari themselves and 3DO leap-frogged what would have been the next generation (consoles like Atari's Panther), so by the time the other consoles companies started designing their's, they had to one-up the Jaguar&3DO, so basically since that time new consoles have been on a par, more or less, with computers (at the time of release, computers always steadily advance where consoles take jumps). The Jaguar and 3DO, when released, were as powerful as the current PC's of '93-4. Dose that make any sense to anyone?

[justclaws]

Hello,

 

All nice points, by everybody, nice discussion, and no flaming. :-)

 

Cheers,

JustClaws.

[CrazyChris]

Thanks for the great replies. I always enjoy reading

stuff about the Jag.

 

Chris

[JagChris]

I know I've heard this before, but I can't remember? From a hardware standpoint why is the Jaguar not good at texture mapping? Please elaborate.

 

Chris

 

My understanding is it does ot have enough fast Video Ram to throw textures to the screen fast enough.

[SteveW]

I remember reading something on Slashdot posted by John Carmack from id Software about the problem with texturemapping on the Jag. Something about scratchpad memory instead of real memory. I can't remember the details.

[JagChris]

I remember reading something on Slashdot posted by John Carmack from id Software about the problem with texturemapping on the Jag. Something about scratchpad memory instead of real memory. I can't remember the details.

 

Yeah, I remember someone reposting that on here somewhere. If my memory servers(it might not) he basically said not enough fast Video Ram. Something like if it had just a little bit more it would of been 3x faster at texture mapping. Then something about what a shame it was.

[goatdan]

The Jaguar can't do texture mapping because, quite frankly it wasn't designed to do texture mapping. It can do 3D shading quite good, as that is what it was made for, but texture mapping wasn't a big deal until the Playstation really took it to a new level. Before that point, the best-looking 3D games had been stuff like Virtua Fighter and Virtua Racing -- both games based on shaded polygons and not texture mapped polys.

 

Had Atari focused on making fun, polygonal games for the Jaguar instead of attempting to get it to do things it couldn't with texture mapping, I think we would've had a lot more hits on our hands like Battlemorph and a lot less duds like Fight For Life.

[Stone]

I remember reading something on Slashdot posted by John Carmack from id Software about the problem with texturemapping on the Jag. Something about scratchpad memory instead of real memory. I can't remember the details.

 

Yeah, I remember someone reposting that on here somewhere. If my memory servers(it might not) he basically said not enough fast Video Ram. Something like if it had just a little bit more it would of been 3x faster at texture mapping. Then something about what a shame it was.

More? It doesn't have any

 

Stone

[agradeneu]

Lets out it so: The Jag can do Texmaps and it wasn't even bad in 1993 - compared to other systems like PC or 3DO. (BTW I wouldn't compare it to modern 3D cards, Justclaws)

 

Iron Soldier II shows that the Jag can do a mix of shaded, source lighted and textured polygons quite well.

I agree to Gunstar that the Playstation was the real breakthrough for fully texture mapped, source lighted 3D graphics.

However, the Jag can do texs and not bad for its time.

Otherwise explain games like BIWN, IS2, HS CD etc.

 

BTW PCs did all Gfx by software and the CPU, no dedicated hardware for gfx or 3D rendering - and there were texture mapped 3D games like Doom, Descent, System Shock etc.

The Jag was better than the common PC in 1994.

[justclaws]

Lets out it so: The Jag can do Texmaps and it wasn't even bad in 1993 - compared to other systems like PC or 3DO. (BTW I wouldn't compare it to modern 3D cards, Justclaws)

I agree, it wasn't bad at the time, but I think Chris was asking from the viewpoint of later systems, like the PS1 and N64, or even a modern PC. I'm certainly not comparing it to a PC graphics card, but it's good to explain what the difference is, I think, in a modern system like that.

 

Iron Soldier II shows that the Jag can do a mix of shaded, source lighted and textured polygons quite well.

Yes, but Gouraud shading was what the Jaguar was designed to do.

I'm sure that Flare could have done better if texture mapping had

been on the radar, I guess they'd have added blitter RAM as well.

 

BTW PCs did all Gfx by software and the CPU, no dedicated hardware for gfx or 3D rendering - and there were texture mapped 3D games like Doom, Descent, System Shock etc.

The Jag was better than the common PC in 1994.

Yes, indeed, one could ask "Why is a 486 with an ISA bus VGA card not good at texture mapping?" That would be a fair comparison and equivalent question.

 

Cheers,

JustClaws.

[Goochman]

The common PC in 1994 was Pentium based class PC's. This is right about the time the Pentium 60 and 90 came out.

[justclaws]

The common PC in 1994 was Pentium based class PC's.

No, the common systems were still 486, but Pentium systems were

indeed definitely available! Your experience may be different though!

 

This is right about the time the Pentium 60 and 90 came out.

Absolutely, but not everybody can afford to replace all their systems

just because a new CPU comes along! It was new PC, or a new Jag!

 

I worked at a university in the UK, from 1992-1998. Trust me, we

still had a good number of 486 based systems (even though IT was

a major subject) running Windows 95, when I left there in May 1998.

 

Anyway, I digress...

In any case, a Pentium system still didn't have any 3D graphics

cards like today, and texture mapping was certainly not common.

Games like Doom was absolutely leading edge, and there were also

complaints that it would not run on the average system, but it was

a real incentive to upgrade, at least most people I knew could run

Wolfenstein 3D. EGA PC games were still common as shareware!

 

I respect your experience, but I'm sure of my own experiences!

 

Regards,

JustClaws.

[agradeneu]

Plus till the arrivement of MMX there was no logic for gfx in a PC CPU, even if it was Pentium. BTW when i bought my Jag, a friend of mine bought a 486 PC and it was a big deal for him. But the Jag was quite a match, he was somewhat impressed, that an home video system could do so well with 3D gfx...

 

@ JustClaws: Yes, agreed. Texmaps were definitely seen as the crop of the icecream when the Jag was designed; like this way: Oh look these fast polygons - and there are some little textures too!

From what I heard and read and paying respect to my limited knowledge of hardware tech, I would say that the Jag was never designed for shifting big sized textures, which are inevitable if you want fully texmapped games.

Just look at IS 2: they had really a hard time to implent these ground textures and they still are quite undetailed and simple blocks.

 

Another thing is if the Jag could gain speed if the games would run in 256 colors instead of 16-bit color. By a close look to some games on the Sega Saturn I would assume that most of its programs are running in 256 color and low res.

And that's despite the Sat is regarded as the better machine in 3d gfx!

[JagChris]

I remember reading something on Slashdot posted by John Carmack from id Software about the problem with texturemapping on the Jag. Something about scratchpad memory instead of real memory. I can't remember the details.

 

Yeah, I remember someone reposting that on here somewhere. If my memory servers(it might not) he basically said not enough fast Video Ram. Something like if it had just a little bit more it would of been 3x faster at texture mapping. Then something about what a shame it was.

More? It doesn't have any

 

Stone

 

 

Right, and that seems to be the big problem.

[Gunstar]

Another thing is if the Jag could gain speed if the games would run in 256 colors instead of 16-bit color. By a close look to some games on the Sega Saturn I would assume that most of its programs are running in 256 color and low res.

And that's despite the Sat is regarded as the better machine in 3d gfx!

 

this is a GOOD point, and I'd also like to point out that most PSX games are in 256 8-bit color too! If you want to see what the Jaguar is capable of in 8-bit color depth (the devlopers FIRST attempt too), just look at Zero5. If more 3D Jaguar games did use 8-bit 256 color gfx instead of going with 16-bit 65,000 mode all the time some of those 3D games would be much faster and smoother.

[Gunstar]

And just compare the Satrun's Alien Trilogy game to the Jaguar's AvP...it has a more advanced 3D engine (with stairs and different levels and looking up&down), but the texturing and overall graphic "look" with it's 256 color textures is terrible looking compared to Jaguar's AvP with much higher color depth 32,000+(?)

[justclaws]

More? It doesn't have any

Actually that's not quite right. It has 2MB!!!

 

The Jaguar has a unified memory architecture, where all RAM

is main/video RAM, this is what offers the enormous flexibility that

offers programmers numerous options and choices for the games!

 

If the system had only had a fixed frame buffer, like traditional

systems, then the object processor concept could not have been

implemented. Forget the mixed colour depths, unlimited parallax

choices, dynamic scaling, dynamic object lists, enormous choice

of resolutions, and limit yourself pages of video RAM. No way...

 

Think differently, abandon the frame buffer, and be liberated...

 

Cheers,

JustClaws.

[JagChris]

More? It doesn't have any

Actually that's not quite right. It has 2MB!!!

 

The Jaguar has a unified memory architecture, where all RAM

is main/video RAM, this is what offers the enormous flexibility that

offers programmers numerous options and choices for the games!

 

If the system had only had a fixed frame buffer, like traditional

systems, then the object processor concept could not have been

implemented. Forget the mixed colour depths, unlimited parallax

choices, dynamic scaling, dynamic object lists, enormous choice

of resolutions, and limit yourself pages of video RAM. No way...

 

Think differently, abandon the frame buffer, and be liberated...

 

Cheers,

JustClaws.

 

Excellent, we will be expecting a game utilizing all of these concepts from you forthwith.

[Stone]

More? It doesn't have any

Actually that's not quite right. It has 2MB!!!

Only if you abandon any speed of program execution...

 

I was talking about dedicated video RAM - I remember reading the PSX only had 512KB, which would have helped the Jag hugely.

 

Stone