- SEPTiC DEMO'S COLLEGE -- 

                                  Classes for 3 
                                  ????????? 
                         Written by Vicious / Septic 

                                  May 22 93 



                                  Introduction 
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We run with Lesson 4. Unfortunately, I have not had much time to 
to make this part of the demo school, because I keep on struggling with our 
demo to demo the competition in Gothenburg in Pentecost! Unfortunately, it appears not to 
I can be ready, but in all cases, I have taken a little pause, and 
who briefly hooked up this lesson. The show is not very new, 
but you must stick to steel the next time, then I will drive ahead with 
sprites! Enjoy! 


                                    Theory 
                                    ????? 
Pictures can be very nice to Amigan, and they are usually very attractive 
at higher resolutions. Therefore, I shall now show how to view a 
hogupplosningsbild in 16 colors, namely Splash II of Scuba / X-Trade. A 
very nice picture, I think. 
   The show hires, that is 640 pixels in the X-point instead for 320 is pretty easy. 
It is just HIRES-piece in BPLCON ($ DFF100) it's resolved, plus the 
we must set some new DDFSTRT and DDFSTOP. 
   To display more pixels in the Y-point, however, is difficult. Then, relying 
Interlace, which gives 512 pixels instead of 256 in height. Interlace 
works by first showing all the odd lines, and then, at the next 
vertical blanking, shows the smooth lines. This requires a change 
bitplanspekarna at each vertical blanking, and Commodore says it 
should use an interrupt to this. However, I have a better method, 
namely to make copper manage it on their own. 
   It works so that the copper in the first and bitplanspekarna 
then of course change its starting address, so that the other is pekarna 
the next time that copper is running. This you can see that I have done in 
program example. 


                                  Register 
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HIRES + interlace requires that the respective pieces of BPLCON0 
($ DFF100). Difficult it is not, so there's no need for new records. But look 
Please check back at the records in Lesson 3 if you do not remember them. 


                               Program example 
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The program this time is a slight modification of the last lesson in 3. 
I have done about it Hires + Interlace images, and added a 
Fade-routine. 
   Fade-routine work so that it in turn compare the current 
fargvardets red, green and blue values of the destination-fargvardets red, 
green and blue value and raise or lower it depending on the difference 
between them. Routine is able to feud a palette to another, and 
need not necessarily go from black to the destination and 
on the contrary. 
   Hope you understand how it works, I'm a bit time-pressed right now, so 
I have not really time to explain. 


                                  Challenge 
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The challenge was of course not direct any storm successfully, but I received two grants 
that made me very happy! Thank you, thank you for your interest, and Nicolas 
Matrix! 
   Nicolas, your routine was perhaps not quite accurate, but still quite 
the nerve! A small tip only! Wait never with a loop command: 

loop: move.l # $ FFFF, d2 
         dbf d2, loop 

because this is so very different is continuing on the Amiga with various fast 
processor. Instead use vertical blank-sync, a routine waiting 
on the beam breaks, for this to go as fast on all computers. 

   Matrix, your fade-routine was very good! And as far as I can see, quite 
correct! Well done! Unfortunately, we have no prize money in this challenge :-) 
but you may be content yourself with an honorable mention. Your routine was shorter than the 
I have included here, but I can do on the other hand, different colors, 
any speed, fade which way whatsoever, so it compensates well the 
whole. Besides, Matrix, you needed a sinus maker! Download Sine Creator 
v1.11 from 22 AA! The hope I will do, although it would need 
updated soon (Hallo, Leviticus :-))) 
   No new challenge this time, so hang in there until the next time! 


                                   Questions 
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I have had some interesting questions that I was going to respond to this ... Give me 
Please more like this! 

   "It would It would be interesting for you in any future issues or 
just for me to explain how blittern works, and particularly what Minterm, 
Mask and the module contains. " 
  -> Of course, I will this! Blittern is the most powerful in the whole 
Amigan, so why should I skip it! It is very important in 
demo programming, but I will not take it up until the lesson 8! 

   "Why did you write the value in 5200 and not 5000 to BitplaneControl0? 
What has been 2nd to function? " 
  -> The answer is that I do not really know! It has something with video cards, 
Maybe 24-bit short, to do. I always turn to it for nearly all 
others do it! There is no necessity, but surely good to do it! 

   "Can you JUST perform SWAP command in the data records? Is the address registers 
and data registers equivalent in addition to the specific address of the stuff you can 
do with the address of the records? " 
  -> You can only use the SWAP on computer! Otherwise, the records rather 
equal, just some stuff is different, like SWAP, and DIV and MUL as 
just go to do on the computer, and LEA, which only goes to 
address register. 

   "What is DBF for? I understand the function ..." 
  -> Deadly Boring Function! Hehe, no, I can find no meaning in my 
Little 68000-book, so I do not really know what it stands for. 

  "Dc.w $ 008e, $ 2c81; DIWSTRT; *** What are you *** \ / 
      dc.w $ 0090, $ 2cc1; DIWSTOP; *** with here???? ***! " 
  -> This is an excerpt from a copper list. Copper instructions, I went 
through the lesson 1! These are two MOVE commands, which is equivalent to 
CPU: 
    MOVE.W # $ 2c81, $ dff08e 
    MOVE.W # $ 2cc1, $ dff090 
   The records and what they mean, I went through in class 3, so 
look there if there are those you do not understand! 

If there is something you do not understand or who you are, I reply more 
than happy to your questions. Ideally (if you have access to the modem) through 
that you are calling to 22 Acacia Avenue: 

         Nod.1: 036 - 378,007 - 14400BPS DS - 315MB / A3000 
         Nod.2: 036 - 371,021 - 14400BPS HST - Cnet / 25 MHz 

You can also write to me, but then you must enclose the reply postage so that I 
will not be penniless! The address is: 

                               Vicious Septic 
                                Klosterg. 19 
                              S-56792 Vaggeryd 


                                  Finally 
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Each new lesson in this course is published every other weekend at 22 Acacia 
Avenue of the special "Demo Course" area that I also suboperator 
too. Where can you write me letters, and debate on the demo programming. 
Programs that may be necessary to have in the future will also be 
available there. 
   The next lesson will be on the base on June 5, so make sure you call and when 
download it! 
   Now it was the end of this time! Cynez!