nullDC WIP Report thread

[shashClp]

Originally Posted by PsyMan

It will be known when the time comes as the whole thing is WIP at the moment.
Patience ppl

Nice, I didn't meant to know NOW, just that it'd be nice that this information was not private at release time (if ever)

[Xtreme2damax]

Originally Posted by PsyMan

It will be known when the time comes as the whole thing is WIP at the moment.
Patience ppl

Ok, sorry. Please forgive me, don't be mad be glad. J/K

Anyways congratulations it's nice to know the DC is still cared about enough for emulation and that nulllDC is actively being worked on still. I was just afraid back when nullDC was fresh of it ending up going the way of Chankast.

Definitely looking forward to this.

Btw, has anyone been able to successfully contact anyone on the Chankast team to get an official statement on whether it's dead or if it's still being worked on, any news etc.....

[RAY16]

I'm curious, what is it about the way that the DC does Z-Buffering and 2D rendering that makes it so "hard" (not that I think anything about emulating a console is easy, mind you) to get around clipping and transparency issues? Chankast had this problem, and so does NullDC. Is it just an unavoidable byproduct of being in the early stages of emulation, or is there something that makes it a pain to do properly regardless?

[Linktothepast]

Originally Posted by RAY16

I'm curious, what is it about the way that the DC does Z-Buffering and 2D rendering that makes it so "hard" (not that I think anything about emulating a console is easy, mind you) to get around clipping and transparency issues? Chankast had this problem, and so does NullDC. Is it just an unavoidable byproduct of being in the early stages of emulation, or is there something that makes it a pain to do properly regardless?

I am not an expert, but everything is due to the video card of the console (power vr2). It used a different way to display the environment, by not processing anything that is overlapped by something else (if a human was behind a tree, the system would not bother to process him whatsoever). Although effective , this architecture had trouble implementing transform & lighting and later directx capabilities, and it was dropped. Two products were made for the pc market, Kyro and Kyro 2 if i remember correctly, both were pretty good if you take into account their specs (they were performance wise competitive with way better cards at specs). Kyro 1 was quite similar to the dreamcast gpu by the way. A three million polygon per sec card could be on par with a fifteen million polygon card on paper.

[RAY16]

Originally Posted by Linktothepast

I am not an expert, but everything is due to the video card of the console (power vr2). It used a different way to display the environment, by not processing anything that is overlapped by something else (if a human was behind a tree, the system would not bother to process him whatsoever). Although effective , this architecture had trouble implementing transform & lighting and later directx capabilities, and it was dropped. Two products were made for the pc market, Kyro and Kyro 2 if i remember correctly, both were pretty good if you take into account their specs (they were performance wise competitive with way better cards at specs). Kyro 1 was quite similar to the dreamcast gpu by the way. A three million polygon per sec card could be on par with a fifteen million polygon card on paper.

I checked the Wiki entry for the Power VR2 chip after reading your post. Apparently it's called Tile Based Deferred Rendering.

The PowerVR chipset uses a unique approach to rendering a 3D scene, known as Tile Based Deferred Rendering (often abbreviated as TBDR). As the polygon generating program feeds triangles to the PowerVR driver it stores them in memory in triangle strip format. Unlike other architectures, polygon rendering is not performed until all polygon information has been collated for the current frame – hence rendering is deferred.

In order to render, the display is split into rectangular sections in a grid pattern. Each section is known as a tile. With each tile is associated a list of the triangles that visibly overlap that tile. Each tile is rendered in turn to produce the final image.

Tiles are rendered using a process similar to ray casting. Rays are cast onto the triangles associated with the tile and a pixel is rendered from the triangle closest to the camera. The PowerVR hardware typically calculates the depths associated with each polygon for one tile row in 1 cycle.

The advantage of this method is that, unlike with a more traditional z buffered rendering pipeline, work is never done determining what a polygon looks like in an area where it is obscured by other geometry. It also allows for correct rendering of partially transparent polygons independent of the order in which they are processed by the polygon producing application. However, this capability was only implemented in Series 1 and 2. It has been removed since for lack of API support and cost reasons. More importantly, as the rendering is circumscribed to a tile at a time, the whole tile can be in fast onchip memory, which is flushed to video memory before passing on to render the next tile. Note that, under normal circumstances, each tile only needs to be visited once per frame.

PowerVR is not the only pioneer of tile based deferred rendering, but the only one to successfully bring a TBDR solution to market. Microsoft also conceptualised the idea with their abandoned "Talisman" project. Gigapixel, a company that developed IP for tile based deferred 3D graphics, were bought by 3Dfx, who were subsequently bought by Nvidia. Nvidia has no official plans to pursue tile based rendering at present.

Intel uses a similar concept in their integrated graphics solutions. However, their method, coined Zone Rendering, does not perform full hidden surface removal (HSR) and deferred texturing, therefore wasting fillrate and texture bandwidth on pixels that are not visible in the final image.

Recent advances in hierarchical z buffering have effectively incorporated ideas previously only used in deferred rendering, including the idea of being able to split a scene into tiles and of potentially being able to accept or reject tile sized pieces of polygon.

Interesting info. For me, at least.

Hopefully it'll be possible to find a solution the the problems in the future.

[Linktothepast]

Hmm, i just saw a couple of websites my shelf, including the wikipedia.

PowerVR - Wikipedia, the free encyclopedia

Graphics IP cores, 2D/3D accelerators which support a broad range of applications including those in mobile, consumer and computing segments.

PowerVR: 2D, 3D and digital video IP cores for consumer electronics devices including PCs, TVs, arcade machines, games consoles, digital set-top boxes, handheld devices and in-car information and entertainment systems.

I must say i am pretty impressed. I didn't know that they currently do gpu's for mobile phones and are quite successful (like iphone for example). Just by looking at the specs and demos (13,5 milion polygons per sec with a 8mm2 die shrink at 90 nm process is amazing). Just look the bottom url demo. Something tells me we will see something like that at the next Gameboy or nintendo ds console, it is both very energy efficient and good.

[wasilisk78]

Originally Posted by PsyMan

1 picture = 1000 Words so...

It is simply magnificent!

[drkIIRaziel]

Its not the tile based rendering that is the problem, you can emulate that accurately with current rasterisers.The problem is that pvr supports many features on that current cards have dropped, like acum buffers, palettes, 32 bit IEEE float Z buffer etc.It also has some unique features (like per pixel aplha sorting) that only existed on the clx2-based pc cards (NEON250 iirc).The main problem is the 32 bit float Z buffer, thats what causes most layering problems.All the others (as far i tried/planned) can be emulated.Shadows and alpha sorting are based on the Z buffer so the Z problems make these things problematic.I also try to support as many cards as possible and this leads to quality compromises.

[RAY16]

Originally Posted by drkIIRaziel

Its not the tile based rendering that is the problem, you can emulate that accurately with current rasterisers.The problem is that pvr supports many features on that current cards have dropped, like acum buffers, palettes, 32 bit IEEE float Z buffer etc.It also has some unique features (like per pixel aplha sorting) that only existed on the clx2-based pc cards (NEON250 iirc).The main problem is the 32 bit float Z buffer, thats what causes most layering problems.All the others (as far i tried/planned) can be emulated.Shadows and alpha sorting are based on the Z buffer so the Z problems make these things problematic.I also try to support as many cards as possible and this leads to quality compromises.

Ah. Thanks for the info. I don't know much about the more technical aspects of this sort of stuff but it still interests me to a certain degree.

[agent]

Believe it is the most perfect. A great progress

[softypolimer]

I got stuck on that part of the game..........heh

I guess you gonna fix it, right? nice job btw

[PsyMan]

It looked like another ordinary day with nothing to break the boredom... and it was actually...
Then raz contracted me in order to show me the latest minor changes he made to his maple plugin.

Much to my surprise VMU emulation was there and it looks good enough. Apart from the VMU screens that provide some minor (or not so minor) information for each game, saving seems to work fine on games that had problems so far (Dynamite Cop would crash if a VMU was selected, Soul Reaver and Spawn would refuse to save, etc.).

Enjoy the 2 crappy screenshot of Dynamite Cop using the VMUs (yes I was too bored to make more shots).

[Megalon]

wow great news can't wait for there next release!!

[wasilisk78]

Good news. Nicely looks.

[shogun_nihon]

Awsome, VMU emulation I can´t believe it.

[Harlay]

that will be good if the vmu screen can be display in fullscreen.
just like the makaron do.

[drkIIRaziel]

Yeah, it will be good.Guess it depends on if i get around implementing that and on the weather.Deffinately on the weather.

[Tree Dude]

You get handed full VMU emulation, and your bored? I would have spent all day raising a Chao...

[AlphaProspector]

Everything is so silent at the moment. Feels like the calm before the storm.

Good luck with the emu release. Can't wait to put my claws on the VMU emulation.

[jr2nd]

Originally Posted by AlphaProspector

Everything is so silent at the moment. Feels like the calm before the storm.

Good luck with the emu release. Can't wait to put my claws on the VMU emulation.

i know what ya mean.. lol with the exception of pj64 this is the only other emulator i play alot, partially because its the only one that allowed me to play SC at allmost full speed on my low end pc

waiting for the new version is so.. "hurrrryyyyyyy!! i cant wait any longerrrrrr" lol

keep up the good work NullDc is the best and im glad its still active!