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base:techtech_fli [2016-04-21 13:14] – compyxbase:techtech_fli [2016-04-21 13:48] – added link to other tech-tech article compyx
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 ===== Introduction ===== ===== Introduction =====
  
-Below is an example of a tech-tech effect, achieved using a so-called FLI-routine. This is **not** a tech-tech with a FLI logo, its a simple character set based routine using FLI to allow videoram switching at every rasterline.+Below is an example of a tech-tech effect, achieved using a so-called FLI-routine. This is **not** a tech-tech with a FLI logo, its a simple FLI based routine to allow videoram switching at every rasterline. 
 + 
 +The routine differs from [[magazines:chacking7#tech-tech_-_more_resolution_to_vertical_shift]|this article]] in that it uses videoram banks to create the tech-tech, not character sets. One could combine these two techniques by cleverly interleaving character sets and videoram to allow for a wider sinus, perhaps even bank switching with $dd00 for even more movement. I'll leave that as an exercise for the reader ;) 
 +  
  
 I wrote this code as part of an attempt to regain my old VIC-trickery skills, it's been about 25 years since I did a tech-tech. As such, the code may not be up to today's standards. I just published it here since there was no article on tech-tech's using $d011/FLI. I wrote this code as part of an attempt to regain my old VIC-trickery skills, it's been about 25 years since I did a tech-tech. As such, the code may not be up to today's standards. I just published it here since there was no article on tech-tech's using $d011/FLI.
 +
 +Note: I don't explain FLI in detail in this article, there are other articles here which explain FLI properly. 
  
 The code can be assembled by using [[https://sourceforge.net/projects/tass64/|64tass]]: The code can be assembled by using [[https://sourceforge.net/projects/tass64/|64tass]]:
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-====== The Theory =====+===== The Theory =====
  
 //I'll use the word 'logo' here to simplify things a bit. My code doesn't actually include a logo, just some text //I'll use the word 'logo' here to simplify things a bit. My code doesn't actually include a logo, just some text
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 ; sinus = 9 ; sinus = 9
-lda #$1d+lda #$1e
 sta $d011 sta $d011
 lda #$01    ; 9 & 7 == 1 lda #$01    ; 9 & 7 == 1
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             ; one column to the right             ; one column to the right
  
-; and so on for each line of the logo+; and so on for each line of the logo, wrapping the $d011 
 +; value around from $1f to $18
 </code> </code>
  
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 ===== The Code ===== ===== The Code =====
  
-Here's the actual source code, in 64tass syntax. The FLI routine needs to be unrolled, the sinus calculation can all be done in a loop, but that eats cycles, so I also wrote some unrolled code for the $d016/$d018 values updating:       +Here's the actual source code, in 64tass syntax. The FLI routine needs to be unrolled, the sinus calculation can all be done in a loop, but that eats cycles, so I also wrote some unrolled code for the $d016/$d018 values updating. 
 + 
 +Before assembling, one should probably comment out the references to the music, I would be surprised to see everyone having their HVSC at "/home/compyx/c64/HSVC" ;)
  
 <code 6502tasm> <code 6502tasm>
base/techtech_fli.txt · Last modified: 2016-04-22 12:41 by compyx