Saturn transparencies
- Thread starter it290
- Start date
Yeah, I meant storing textures and the framebuffers on the same RAM. Even if it does that, would the VDP1 allow drawing outside the backbuffer area?
I lean towards the software renderer theory for Burning Rangers because it would make more sense on the Saturn if getting the VDP1 to draw to an off-screen buffer and transfer the result to the VDP2 bitmap RAM proved unfeasible.
Skilled programmers with Saturn experience (Sonic Team) would have no trouble getting the slave processor to handle drawing directly into a format the VDP2 can deal with. AMOK's voxel engine was an impressive demonstration on how well a dual processor system like the Saturn can deal with software rendering.
From the Saturn FAQ By John JHokansonJr
------
5.1 Can the Saturn perform transparency and light sourcing effects?
-------------------------------------------------------------------
The answer depends on the context in which this question is asked.
The Saturn is at *least* capable of generating transparent layers for
use in 2D spirte-based images. Furthermore, pseudo 3D transparencies
(like the water in Panzer Dragoon) are also possible. These effects
can be done directly by the VDP2.
If anybody doubts this (and there have been a few), you can check out
games such as Astal, Darius Gaiden, and Radiant Silvergun. These are
but a few examples. You can also simply powerup your Saturn and check
out the system settings. The menu screens themselves provide a
glimpse at the Saturn's layered transparency effects. Effects such as
these are nothing really new, as they were seen earlier on Nintendo's
Super Famicom, and perhaps on other platforms that preceded the
Saturn.
Where the Saturn does have trouble, is in the generation of these
effects in a 3D environment. Along with lightsourcing, three
dimensional transparency must be generated through software code.
This is not a problem if the developer is familiar with writing
Saturn software or was provided with the necessary programming
libraries. For instance, Sega's "Sonic-R" features 3D transparency
throughout the "Radiant Emerald" course, and lightsourcing can
clearly be seen along the corridors of Lobotomy's "Powerslave"
("Exhumed" in the UK).
Brian Osserman <osserman@math.mit.edu> writes:
"The situation with transparencies on the Saturn is exceedingly odd.
The most common kind is via the background processor, which can more
or less put two properly texture-mapped translucent perspective
correct planes. This is what Panzer Zwei and Panzer Saga use for
water, for instance. Beyond this, I don't remember the details, but
Sonic R and Burning Rangers seem to use two different hacks to get
non-dithered transparencies. I can't remember whether there are any
other examples, though. I think these were cases of exceedingly
clever programming, though, and it's no coincidence they were both
late in the Saturn's lifetime."
-----------------------------------------
The Saturn is equipped with dual custom VDP chips for graphics
processing.
The VDP 1 chip is primarily responsible for sprite generation.
Polygon generation is accomplished through manipulation of the
sprite engine. Texture mapping and goruard shading is also handled
by the VDP 1. The VDP1 relies on a dual frame buffer that handles
rotation and stores textures in special 512K cache.
The VDP 2 serves as the Saturn's background processor. Certain
special effects such as texture transparency and playfield rotation
and scrolling (up to five fields at any given time) are handled here.
Both VDP chips have direct access to the both SH2s, as well as
direct memory access (DMA) to both the main and video RAM.
------
5.1 Can the Saturn perform transparency and light sourcing effects?
-------------------------------------------------------------------
The answer depends on the context in which this question is asked.
The Saturn is at *least* capable of generating transparent layers for
use in 2D spirte-based images. Furthermore, pseudo 3D transparencies
(like the water in Panzer Dragoon) are also possible. These effects
can be done directly by the VDP2.
If anybody doubts this (and there have been a few), you can check out
games such as Astal, Darius Gaiden, and Radiant Silvergun. These are
but a few examples. You can also simply powerup your Saturn and check
out the system settings. The menu screens themselves provide a
glimpse at the Saturn's layered transparency effects. Effects such as
these are nothing really new, as they were seen earlier on Nintendo's
Super Famicom, and perhaps on other platforms that preceded the
Saturn.
Where the Saturn does have trouble, is in the generation of these
effects in a 3D environment. Along with lightsourcing, three
dimensional transparency must be generated through software code.
This is not a problem if the developer is familiar with writing
Saturn software or was provided with the necessary programming
libraries. For instance, Sega's "Sonic-R" features 3D transparency
throughout the "Radiant Emerald" course, and lightsourcing can
clearly be seen along the corridors of Lobotomy's "Powerslave"
("Exhumed" in the UK).
Brian Osserman <osserman@math.mit.edu> writes:
"The situation with transparencies on the Saturn is exceedingly odd.
The most common kind is via the background processor, which can more
or less put two properly texture-mapped translucent perspective
correct planes. This is what Panzer Zwei and Panzer Saga use for
water, for instance. Beyond this, I don't remember the details, but
Sonic R and Burning Rangers seem to use two different hacks to get
non-dithered transparencies. I can't remember whether there are any
other examples, though. I think these were cases of exceedingly
clever programming, though, and it's no coincidence they were both
late in the Saturn's lifetime."
-----------------------------------------
The Saturn is equipped with dual custom VDP chips for graphics
processing.
The VDP 1 chip is primarily responsible for sprite generation.
Polygon generation is accomplished through manipulation of the
sprite engine. Texture mapping and goruard shading is also handled
by the VDP 1. The VDP1 relies on a dual frame buffer that handles
rotation and stores textures in special 512K cache.
The VDP 2 serves as the Saturn's background processor. Certain
special effects such as texture transparency and playfield rotation
and scrolling (up to five fields at any given time) are handled here.
Both VDP chips have direct access to the both SH2s, as well as
direct memory access (DMA) to both the main and video RAM.
antime
Extra Hard Mid Boss
The biggest inaccuracies in that text is the claim that 3D transparencies and lightsourcing would be software-only effects. As we know, VDP1 can do its own kind of transparencies and while the lightsourcing parameters must be calculated in software the actual effect can be accomplished using the hardware Gouraud shading capabilities (for flat shading you have more options). Also, the more or less legendary Sonic-R transparent course is just another example of VDP2 blending.
This is an interesting topic - I knew the Saturn was somewhat infamous for its lack of transparencies and cross hatching, but it's interesting to see so many different points and opinions on the topic.
So basically, proper transparency can be accomplished using a combination of hardware and software methods?
(goes to play Radiant Emerald
)
So basically, proper transparency can be accomplished using a combination of hardware and software methods?
(goes to play Radiant Emerald
)Software-based transparency isn't feasible on the Saturn (or most of the systems), unless you're drawing everything using your own, super-optimized software renderer (anyone remember the Zyrinx 32X demo tape? Gouraud shading, additive blending and fog, all using custom renderers).
It's just a matter of clever coding so the game makes use of the avaliable hardware transparency features while trying to avoid the limitations.
Burning Rangers was the only game I know that went with major hacks to abuse the system features.
It's just a matter of clever coding so the game makes use of the avaliable hardware transparency features while trying to avoid the limitations.
Burning Rangers was the only game I know that went with major hacks to abuse the system features.
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