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Stingray
Account closed
Registered: Feb 2003
Posts: 117 |
FASTER 3D GRAPHICS
I've heard it said before that the way the VIC chip addresses memory (8x8 cells) makes it slower fo rendering graphics because of the extra calculations needed. So what way would you have had the Commodore engineers design an alternative addressing mode so that 3D graphics could be calculated quicker? I would realy appreciate your ideas on this. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
yes, a display list would be bloody cool. |
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Krill
Registered: Apr 2002
Posts: 2980 |
Yes, and while we're at it, why not have an easy sideborderless mode where the expansion would flip the $d016 38/40 column bit at the right x positions twice each line automatically? Or the same with $d017 to stretch sprites? Or similar with $d011 for easy FLI/repeated badlines/linecrunching? Oh the possibilities! :) |
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Martin Piper
Registered: Nov 2007
Posts: 722 |
I have a suspicion that having a display list writing to VIC registers during bad lines might not be so easy. This is because the VIC is controlling the whole of the memory bus and bandwidth, i.e. both phis, for the period of the bad line fetches. This is why the CPU is paused during a bad line.
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Krill
Registered: Apr 2002
Posts: 2980 |
This is true, but there are still 23 cycles left for register writes during a badline, and with something like interleaved CPU and display list register writes, more is possible than with only the CPU writes in the cycles left. |
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PopMilo
Registered: Mar 2004
Posts: 146 |
"Display list" is maybe little to much but that is up to stingray to say :)
But those 20+ cycles could definitely be used in some way.
I thought about few bites somewhere in memory that would say to "VIC-III" :) how many lines to repeat.
Values would be 0,1,3 and would only manipulate data on address bus. One line down from bad line VIC would think its getting data from next 40bytes, while VIC-III would change those addresses back to previous 40 bytes... and so on...
Great idea with putting new hardware between VIC and rest of system !!! :)
I don't remember, is VIC in a socket or soldered ?
How hard will it be to insert this contraption ? :)
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Stingray
Account closed
Registered: Feb 2003
Posts: 117 |
First of all thanks for all the input, the input you guys have made has shaped the direction of this project and given me the inspiration to see this project through to the end.
Quoting PopMiloI don't remember, is VIC in a socket or soldered ?
The VIC is socketed on every C64 (thank you Commodore), as far as I know anyway. I believe the SID is also socketed on every C64.
Quoting PopMiloYes, at least in port of Yoomp from Atari :)
Eor filling doesn't help in that case but repeating lines without cpu time would save thousands of cycles each frame...
I checked out Yoomp, very cool game. Are you going to port it? If you are going to port it I will try and help with the hardware. That game would be great for C64 & with nice SID music.
Quoting KrillI think what this implies is actually having display lists akin to what's implemented on Atari8. (See http://en.wikipedia.org/wiki/ANTIC)
Quoting Oswaldyes, a display list would be bloody cool.
I have had this in mind for some time, I have been reluctant to include it in the spec for fear of disappointing ppl in the case that I don't not implement it in the end.
I was leaving this as on of those things I could do at the end after having done everything else I have already committed to doing with the project. But when I hear you guys and Krill say stuff like the followingQuoting KrillYes, and while we're at it, why not have an easy sideborderless mode where the expansion would flip the $d016 38/40 column bit at the right x positions twice each line automatically? Or the same with $d017 to stretch sprites? Or similar with $d011 for easy FLI/repeated badlines/linecrunching? Oh the possibilities! :)
Really inspires me to make sure I include this kind of thing, in fact I am now thinking I will do it, permitting I have enough real estate in the CPLD and enough time (I have now imposed a Deadline of sorts for this project on myself).
Quoting Martin PiperI have a suspicion that having a display list writing to VIC registers during bad lines might not be so easy. This is because the VIC is controlling the whole of the memory bus and bandwidth, i.e. both phis, for the period of the bad line fetches. This is why the CPU is paused during a bad line.
You are 100% spot on Martin, while AEC is low, Vic can not be written to.
BTW, Can we call this something other then a Display List? We can come up with a better name then what those Atari guys use can't we? I have never really thought of what I had i mind as a Display List but more of a Direct Loader. Lets say the there are 19656 cycles per screen (the first being at the very start of the first raster). You can say, ok load VIC register $21 with #$01 on cycle 3150 etc.. Keeping in mind two things, that you can not do this on a bad cycle + you can't have 6510 write to VIC at the same time (If both write to VIC at once 6510 will be ignored). You will also gain a few cycles on a badline for Direct Loading as you could still Direct Load while BA is low.
Just to put it a simpler way, you can load any value into any VIC register on any of the 19656 cycles that make up a screen, as long as it's not a badcycle.
It would even be possible to change the background color (or any VIC register) on every cycle!! as long as not on a badcycle. The more I think about the more we need this, in fact I'm kinda thinking now that If I don't include this I am kind of wasting the project.
Is "Direct Loader" a good enough name for this part of the circuit?
Also will this allow PopMilo to port his game? I guess he would use the Direct Loader to FLD?? |
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Stingray
Account closed
Registered: Feb 2003
Posts: 117 |
VIC X (VIC eXpanded / VIC eXtreme): 2 VOTES
BAD VIC : 1 VOTES
Notorious V.I.C : 1 VOTES
Alien VIC : 1 VOTES (My own vote)
VIC ENHANCER : 0 VOTES
VIC UNLEASHED : 0 VOTES
VIC INTERCEPTOR : 0 VOTES
VIC AAA (Awesome Addressing Add-on) : 0 VOTES
VIC-X is winning!
Need a couple more ppl to vote on a name.
BTW, if I am a bit slow at responding for a few days, I'm not being rude, I am just really getting stuck in to this project ;)
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
Atari8 display lists do not have the ability to write to any register. You are mixing up Amiga Copper with A8 display lists. |
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Martin Piper
Registered: Nov 2007
Posts: 722 |
Quoting stingrayIs "Direct Loader" a good enough name for this part of the circuit?
It is. Or "Copper". :)
I would definitely use the system for everything related to VIC effects. Opening the borders, multiplexing really tight sprite formations, nice expanded graphics screens. Leaving the CPU free to do all the calculation, it would be marvelous. |
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Stingray
Account closed
Registered: Feb 2003
Posts: 117 |
Quoting GrahamAtari8 display lists do not have the ability to write to any register. You are mixing up Amiga Copper with A8 display lists.
Yep, I probably am. Thanks Graham. |
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