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71

General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by 20EnderDude20 on August 19, 2018, 05:30:21 am »

Is SCART basically RGB in another form factor?

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General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by ponut64 on August 19, 2018, 05:18:59 am »

The mesh effect looked ok on crt with composite, which is what people used back then, so it just made sense to use that instead of decreasing your framerate.

That depends on the region , here in Europe we all used RGB since the scart cable came with the console.

I did not know that.
In which case, you've got pixel-perfect display...

73

Project announcement / Re: Sonic Z-Treme

« Last post by 20EnderDude20 on August 19, 2018, 01:06:26 am »

So, is there anything to comment on the progress of sonic z-treme? I would like to know. Thanks.

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General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by jabfg on August 18, 2018, 10:57:39 pm »

The mesh effect looked ok on crt with composite, which is what people used back then, so it just made sense to use that instead of decreasing your framerate.

That depends on the region , here in Europe we all used RGB since the scart cable came with the console.

75

General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by XL2 on August 18, 2018, 07:14:01 pm »

It's not about if you can find the proper angle. You would need that only for square objects, so probably only for the world objects or maybe some platforms. Each pixel takes 6 times the time it takes to draw a normal pixel. It doesn't make sense to have slowdowns for such a small details. And you increase cpu calculations as well. You could just use a msb  distorted sprite if you framebuffer is palette only, you could just precalculate that shadow and use palette swaps to create a shadow (which is what I do) or use another vdp1 color calculation function (like gouraud or half luminance). There are reasons why very few games used half transparency, and it's because of both the bug and the slowdown.
The mesh effect looked ok on crt with composite, which is what people used back then, so it just made sense to use that instead of decreasing your framerate.
Even Burning Rangers used the mesh effect very often.

76

General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by 20EnderDude20 on August 17, 2018, 03:55:02 pm »

But yet again, that 16-frame system might work. You just need the value of the angle of the camera, and you’re pretty much good to go.

77

General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by XL2 on August 17, 2018, 11:00:35 am »

I agree with Corvusd.
It's easy to come up with ideas, but it seems nobody else ever actualy try to write the code themselves.
I've got ideas myself for more transparency (even if my game is filled with vdp2 transparency), but until it's written it's not worth much.
Like if you use vdp2 for sprite over sprite transparency, how do you solve the priorities?
It's super complicated, but most people don't think about these.
Like sure, I can use the NBG0 as a framebuffer, but then all my other sprites need to have the correct priority.
Even Burning Rangers struggled with it, and it was made by one of Sega's best studio.

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General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by corvusd on August 17, 2018, 09:46:03 am »

What's better, dithering, or over-transparency? In my opinion, I would choose something that is real vdp1 transparency, and not the same screen door method that's been used since the genesis. The designers never had the intention of the output being precise, but with s-video, I would rather stick to real transparency, simply because it gives the Saturn a chance of having transparency. Oh, yeah, and I think the n64 can only do 50% transparency because mario in sm64 uses dithering when using a secret warp, so we shouldn't get too ahead of ourselves.

N64 have REAL Alpha Blending. Is a patent of Silicon Graphics. PSX and SS not have Alpha blending, it is wired half-transparency. In its documentation says it clearly all this stuff. We not invent theories or data... already they lied enough in the past: History of millions of polygons on screen at 60 FPS. We stick to the technical data, clearly documented. Please.

Half-transparency is REAL and totally useful in SS. The key is archive the best way to use it without caveats: No Redraw, in 3D primitives and OK blend in all pipeline(VDP1+VDP2).

Example to start whit real approach: Burning Rangers.

In my Table analysis we have at 65 titles whit VDP1 CC half-transparent use. We can research all advantages and disadvantages in each case(geometry, layer, quantity, area pixels, type of color and pool VRAM, size texture, color calculation use it...), and get right conclusion about the objective. In the same way are other column to analysis of VDP2 semi-transparency... Feel free to make research and share!

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General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by 20EnderDude20 on August 17, 2018, 05:56:21 am »

What's better, dithering, or over-transparency? In my opinion, I would choose something that is real vdp1 transparency, and not the same screen door method that's been used since the genesis. The designers never had the intention of the output being precise, but with s-video, I would rather stick to real transparency, simply because it gives the Saturn a chance of having transparency. Oh, yeah, and I think the n64 can only do 50% transparency because mario in sm64 uses dithering when using a secret warp, so we shouldn't get too ahead of ourselves.

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General discussion about the Sega Saturn / Re: Transparent Shading on The Saturn

« Last post by ponut64 on August 17, 2018, 05:32:52 am »

You mentioned the fm towns marty 3D sphere which gave me an idea but then I looked it up on youtube and it was nothing like my idea.

The idea is to use a normal VDP2 layer with small premade tiles and a CPU can decide how to composite the tiles to recreate what looks like any shadows.


The VDP1 draws arbitrary lines from the left line to the right using a greedy algorithm which causes pixels to be overdrawn. This avoids PS1-like gaps but causes the moire pattern with transparency. The other thing that causes the moire pattern was demonstrated well in one of Jon Burton's Sonic R videos. So unless each line is perfectly vertical or horizontal it'll overdraw causing transparency to be bollocks. This applies to skewed and rotated quads, not just perspective corrected quads.


One of the things you might have heard is that CRTs and composite video blurs the dithering enough to be a convincing shadow just drawing a dithered black oval over the ground. I didn't understand just how effective this was until I saw this composite capture of Z-treme on youtube: https://youtu.be/x7cW9wgIW00?t=50
Anyways you can tell how, back in the day, a team on a deadline scraping for ounces of power on a not quite adequate for 3D system would just draw an oval and be done with it.

I think one of the major issues with performance is that we're using an incredibly old jack-of-all-trades graphics library instead of tightly focused custom routines. Unlike a more straightforward graphics system, the saturn's really hard to write efficient graphic routines or even wrap your head around especially the memory scheduling. If two chips try to access the same memory chip in the same cycle, one of them will be halted until it gets access. This can basically throw away many cycles of work the saturn would otherwise be able to accomplish.

Anyways we got some interesting ideas floating around.

I can't blame anyone for being oblivious to this if you hadn't actually played on real Saturn hardware, but:

- The Saturn's AV / composite / yellow cable video signal is among the best (as far as that type is concerned).
- And yes, 100%, the typical transparency effect of blanking out half the pixels works pretty much flawlessly over this signal type. As far as I am concerned, the Saturn is meant to be used this way, and it would be nice if emulators included an image filter for it.
- S-Video, the near-neighbor display type to AV/yellow plug, is also good on the Saturn - in fact it's pretty much pixel perfect, which means the transparency effect is no longer convincing.