leicester not w(y)o(r)kshire
a hazel nut in every bite isnt that what comes out of a squirrel?
2009/8/19 David Sanders <dsuzukisand...@gmail.com>:
> Roger,
> Can we not keep on-topic just slightly? I really don't see what
> relevance the cost of broadband in Hong Kong has to the blue-footed
> one.
> Though actually it's a little like having James Joyce on the list, so
> I'll try not to complain.
>
> David
>
>
> 2009/8/19 Roger Jowett <rogerjow...@gmail.com>:
>> !hd
>> also sim coupe didnt like the full screen or maybe it was camtasia i
>> used to record the desktop anyone got a better one?
>> anyone figure out how to use the tv encoder chip on the vga card - msi
>> mx440 vtd 8x agp /ti4200 vtd 128 / fx5900 zt vtd 128 all msi all Video
>> input video output - none support hi deff despite the manual claiming
>> the tv encoder can encode mpeg with 600mhz proces...@1024x768 - dont
>> seem too hi deff to me!
>>
>> also ati x1950 power colour this had a component input cable with an
>> arrow pointing towards teh machine but guess what
>> also msi digital tv tuner - still only composite and s-video inputs
>> although kind of weirdly the virgn/ntl set top box my brother has
>> actually manages to get the screen to fill the pc tv tuner screen
>> whereas the output from the box never quite works on the tv no matter
>> what setting you try?!
>> maybe use the lan/usb/serial/scart to conenct it to a hi deff tv? need
>> to reflash the bios? not available from ntl/virgin
>> also cant use the cable feed to get hi deff on the pc or the cable
>> cahnnels or the internet have to have adpater for set top box and
>> adapter for a router - was similar in hong kong luckily i had three
>> fans in the card board box above the loos otherwise ida fryed!
>> pccw 6mbps yeah sure engineer tested it never above 300kb and that
>> would have been a miracle
>> ohh you loose 5mbps when you are watching the digital tv service oh
>> yeah well in that case youd have to be giveing me 5mbps in the first
>> place before i could loose what you have never given me in the first
>> place $150 a month christ! crooks
>> can you use the itu t v44 320kbps modem at the same time would
>> increase by 2½ the upload ability at the sneakily unadvertised 256kbps
>> speed (fat chance!)
>>
>> 2009/8/19 Roger Jowett <rogerjow...@gmail.com>:
>>> http://www.youtube.com/watch?v=ALLAUaVoQC0&feature=channel_page
>>>
>>> dunno if youd need a dma for this in mode1 or it'd b n e easier in mode2
>>> will try mode 3 next then if anyone knows an easy to use interlace routine
>>> would the second interlaced screen be one pixel line below the first -
>>> is that how it works its alternate scan lines
>>>
>>> 2009/8/19 Roger Jowett <rogerjow...@gmail.com>:
>>>> but surely the code can be fed into the samc compiler no - sam vision
>>>> erm it looks close?!
>>>> are you sure that as teh filled in cube rotates it wouldnt be easier
>>>> to drop to mode1 couldnt you fill 64 pixels of colour witha single
>>>> byte attribute square only need to work out how many you could get
>>>> away with seems a bit jerk how many frames does it take to draw?
>>>> have you tried the echologia demo with the dma and mb-02+ in real
>>>> spectrum - not sure if they are using the dma tah much some models
>>>> take 3 to 7 frames to draw
>>>> wouldnt a sam dma be a wee bit faster than the quoted 17jb per frame
>>>> velesoft reckon the dma datagear interface handles in on128k
>>>> also do you need masterdos to detect an external sam - its only
>>>> another 3mhz but what about those register hungry emulators like the
>>>> apple and oric or whatever its called oreo - isnt that a biscuit?
>>>> did you catcht eh text font.... its taken me a loooong time
>>>> silver paint tonight pressure sensitive keyboard membrane here i come!
>>>> - didnt realise the 128keypad had a pic controller in it dont they go
>>>> up to 80mhz! theres development kits in maplin £44 or build it your
>>>> self for £25ish grade b=£20
>>>> http://www.maplin.co.uk/Search.aspx?menuno=12483
>>>>
>>>> usb...
>>>>
>>>> http://www.maplin.co.uk/Search.aspx?menuno=12545
>>>>
>>>>
>>>> 2009/8/7 Simon Cooke <si...@popcornfilms.com>:
>>>>> It's still pretty much just a quick sin/cos lookup for the euler angle
>>>>> calculation. As you say, you just store it in a form that hits 0 at 0, and
>>>>> 2pi - epsilon at 65535. (Or something similar), and then just do a lookup.
>>>>> That part's fast.
>>>>>
>>>>> Quaternions... The biggest advantage is that you can interpolate between
>>>>> them - which is necessary for skeletal animation. There are a number of
>>>>> disadvantages though - the need to occasionally renormalize them being a
>>>>> big
>>>>> one. (You're not actually gaining any kind of stability there per se; all
>>>>> you're doing is trading one numerical inaccuracy for another).
>>>>>
>>>>> Here's a case against them:
>>>>>
>>>>> http://www.gamedev.net/reference/articles/article1199.asp
>>>>> http://www.somedude.net/gamemonkey/forum/viewtopic.php?f=12&t=380
>>>>>
>>>>>
>>>>> http://www.sjbrown.co.uk/2002/05/01/quaternions/
>>>>>
>>>>> Note: it may make sense to handle your camera as a quaternion, vs. a
>>>>> rotation matrix for local->worldspace transforms, based on the cost of
>>>>> operations.
>>>>>
>>>>> If you decompose your matrix into all of the pieces you need to calculate
>>>>> when you build it, and keep that alongside all of the pieces you need to
>>>>> apply when you apply it, then you might find more optimization
>>>>> opportunities
>>>>> - especially if you're not performing more than one rotation at once.
>>>>>
>>>>> But ultimately, the name of the game here is to go as far as possible, so
>>>>> it's all going to come down to your use cases.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: owner-sam-us...@nvg.ntnu.no [mailto:owner-sam-us...@nvg.ntnu.no] On
>>>>> Behalf Of Thomas Harte
>>>>> Sent: Wednesday, August 05, 2009 4:13 PM
>>>>> To: sam-users@nvg.ntnu.no
>>>>> Subject: Re: Hi - just checking
>>>>>
>>>>> They're in some format or another that I don't recall offhand, but is
>>>>> lined up so that a full circle is a nice round binary number for the
>>>>> obvious range fixing optimisation. But it's not just a quick sin/cos
>>>>> table lookup unless you're rotating around one axis only. See, e.g.
>>>>> http://www.manpagez.com/man/3/glRotatef/ (the man page for glRotatef)
>>>>> - clearly there's a lot more going on there than table lookups.
>>>>>
>>>>> Of course, I am taking note of coherences. If the angles associated
>>>>> with an object do not change from one frame to the next, the source
>>>>> matrix is not recalculated. This optimisation postdates the version of
>>>>> my code that has already appeared on Sam Revival, but predates the
>>>>> next version (which is a better optimised version of the code shown in
>>>>> my video http://www.youtube.com/watch?v=j0xN_Mi3B_I)
>>>>>
>>>>> As I've posted to this list in the past, I use something vaguely like
>>>>> SIMD to multiply a 2d vector by a scalar - the relevant part of the
>>>>> scalar sits in the accumulator and is shifted there to make the
>>>>> add/don't add decision in the standard binary multiplication formula,
>>>>> meanwhile the 2d vector sits with the work going in for one component
>>>>> occupying BC, DE and HL, the work for the other occupying BC', DE' and
>>>>> HL'. Hence I get a substantial saving on multiplying the two vector
>>>>> components by the scalar separately.
>>>>>
>>>>> Naturally, I have a classic y = f((x^2)/4) table for the limited range
>>>>> multiplications (related to the maximum size an individual object may
>>>>> be).
>>>>>
>>>>> I assume your point about not accumulating transformations in matrices
>>>>> effectively means that you agree that quaternions are useful beyond
>>>>> interpolation and animation (which I'm interpreting quite narrowly to
>>>>> be the traditional skeletal type, not broadly to be any old moving
>>>>> image).
>>>>>
>>>>> Anyway, hopefully I'll be able to get myself in gear for a source
>>>>> release at some point in the near future, then you can rip it apart.
>>>>> It's all geared up to be trivial for other (assembler) coders to use
>>>>> to produce their own programs, handling triple buffering and frame
>>>>> rate compensation with very limited need for work on the part of the
>>>>> programmer (which neatly means that all my code scales really well
>>>>> from a normal Sam to a Mayhem or otherwise accelerated machine), etc.
>>>>> I tidied most of it up for a release quite a while ago but decided to
>>>>> switch to Jam rather than sticking on pyz80 because a lot of stuff
>>>>> would be substantially more compact and more readable with proper
>>>>> macro support. I also would much rather that the demo was seen first
>>>>> on Sam Revival rather than on the internet, both as a pathetic attempt
>>>>> to support the publication and because it looks much better on a real
>>>>> television. Never found time to convert it though, so it'll be a pyz80
>>>>> release.
>>>>>
>>>>> Actually, the demo on the previous Sam Revival was explicitly flagged
>>>>> as PD, so I'll upload a DSK of that demo somewhere once the next
>>>>> edition is out. I think I mentioned every Sam program I've written in
>>>>> the SR article; you can see most of them very briefly in
>>>>> http://www.youtube.com/watch?v=kr_Lz98qVjE&feature=channel_page
>>>>>
>>>>> On Wed, Aug 5, 2009 at 10:16 PM, Simon Cooke<si...@popcornfilms.com>
>>>>> wrote:
>>>>>> Hmmm... what form are you using your Eulers in? If it's radians, it's not
>>>>>> too bad - just a quick sin/cos table lookup. And you only need to do it
>>>>> once
>>>>>> per object if it's a simple rigid body.
>>>>>>
>>>>>> The trick with making matrices numerically stable is that you don't ever
>>>>>> want to do a stepwise transform on an object - you regenerate the matrix
>>>>>> from scratch each time. (This is one of those things you never really see
>>>>> in
>>>>>> practice; most engines split out the rotational transforms and keep them
>>>>>> separate, using either an axis-angle representation, quaternions, or in
>>>>> some
>>>>>> bad cases, euler angles [this is what Unreal uses btw]. That way, you
>>>>>> keep
>>>>>> fidelity - or at the very least, you don't care too much about
>>>>> inaccuracies
>>>>>> as they come in - you can just ignore them if your object is rotated a
>>>>>> little off; it's not a culumlative error).
>>>>>>
>>>>>> Assuming no scaling or shear, just rotation and translation, your
>>>>>> translation is the rightmost column of numbers in the matrix. If all of
>>>>> your
>>>>>> objects are pre-scaled in memory to the right size, all you have to do is
>>>>>> apply the rotation and translation in order to each of the points.
>>>>>> Screen-space projection is a little more difficult, but that one you can
>>>>>> precalc all the divides in.
>>>>>>
>>>>>> On machines without SIMD or dedicated 3D instructions (such as the SAM),
>>>>>> it's nearly always best to break out the matrix into individual linear
>>>>>> equations, take the common pieces and only calculate them once, and then
>>>>>> operate on them that way.
>>>>>>
>>>>>> --
>>>>>> Simon Cooke
>>>>>> Director of Engineering / Business Developer, X-RAY KID STUDIOS -
>>>>>> www.x-raykid.com
>>>>>> Founder, Popcorn Films - www.popcornfilms.com
>>>>>> Cell: 206 250 7892 XBOX Live GamerTag: Spec Tec
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: owner-sam-us...@nvg.ntnu.no [mailto:owner-sam-us...@nvg.ntnu.no] On
>>>>>> Behalf Of Thomas Harte
>>>>>> Sent: Wednesday, August 05, 2009 5:14 AM
>>>>>> To: sam-users@nvg.ntnu.no
>>>>>> Subject: Re: Hi - just checking
>>>>>>
>>>>>> That's not entirely true. Matrices are numerically unstable, so the
>>>>>> cost of ensuring they remain orthonormal when applying consecutive
>>>>>> local transforms in a game such as Elite is substantially greater than
>>>>>> the cost of ensuring that a quaternion remains of unit length.
>>>>>>
>>>>>> I make it 8 multiplies, 3 adds, 1 square root and 1 divide to fix up
>>>>>> numerical error in a quaternion. Conversely, I get 36 multiplies, 21
>>>>>> adds, 3 square roots and 3 divides to fix up an orthonormal matrix.
>>>>>>
>>>>>> Quaternion to matrix is 10 multiplies, 6 shifts and 14 adds. So the
>>>>>> way I calculate it, you can fix a quaternion and convert it into a
>>>>>> matrix in less than you can fix up a matrix. Furthermore, quaternion
>>>>>> composition is 16 multiplies and 12 adds, whereas matrix composition
>>>>>> (with assumptions about the bottom row of a 4x4) is, ummm, at least 36
>>>>>> multiplies and 18 adds. And that's with the translation component not
>>>>>> completely factored in (I'm reading actual code off screen and have
>>>>>> optimised the translation out of this particular batch).
>>>>>>
>>>>>> Elite is also a perfect example of when Euler's aren't fine, even if
>>>>>> they didn't produce Gimbal lock, as all rotation is around local axes
