Fire Demo effect

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danorf
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Fire Demo effect

Postby danorf » Tue Mar 05, 2013 9:22 am

Hi,

I would have wanted to know if anyone has knowing of fire effects in plain ST(F) or STE demos (like the following pic but with movement :mrgreen: ...)
Image

If someone has, may I ask him some technical details :
- plot precise effect or x2, x4, ... (C2P ?)
- real effect or mainly precalculated
- in how many VBL it runs

Thx, for any answer.

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Re: Fire Demo effect

Postby evil » Sat Mar 16, 2013 5:27 pm

danorf wrote:- plot precise effect or x2, x4, ... (C2P ?)


C2P

danorf wrote:- real effect or mainly precalculated


Real effect. In the bottom of a chunky buffer, you add random noise. Then you run a smoothing pass with the smooth result written to the buffer a bit higher than the source.
I'm s h i t (have to write it with spaces or the darn forum writes "poo" instead!) at explaining highlevel, but something like this in 68000;

lea chunky,a0
lea -1(a0),a1
lea 1(a0),a2
lea 160(a0),a3 ;that's one line beneath a0

move.b (a0),d0
add.b (a1)+,d0
add.b (a2)+,d0
add.b (a3)+,d0
lsr.b #2,d0
move.b d0,(a0)+

You do this for each pixel in the chunky buffer, then you also need to c2p it to screen. The pixels chosen for average can be done differently for different result, for example doing +159, +160, +161 would perhaps look better. It's for experimentation.

danorf wrote:- in how many VBL it runs


That my friend is totally up to the level of optimization you can do. The above example with a c2p pass after will certainly not be very optimal, but easy to read.

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nativ
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Re: Fire Demo effect

Postby nativ » Sat Mar 16, 2013 7:05 pm

you could do and 'effect' like this using palette scroll :D :lol:
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Re: Fire Demo effect

Postby danorf » Mon Mar 18, 2013 9:40 pm

So, if I assert that it's possible to make this effect with a "one pixel precision", on a plain ST, with no C2P nor precalculation and in less than one screen frame, most of you may say I'm a fool or, worst, a liar ? :(

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nativ
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Re: Fire Demo effect

Postby nativ » Mon Mar 18, 2013 10:14 pm

:idea: :idea: just make a holder for a row of matches and place it in front of your monitor :idea: :idea:
Atari STFM 512 / STe 4MB / Mega ST+DSP / Falcon 4MB 16Mhz 68882 - DVD/CDRW/ZIP/DAT - FDI / Jaguar / Lynx 1&2 / 7800 / 2600 / XE 130+SD Card // Sega Dreamcast / Mega2+CD2 // Apple G4

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Re: Fire Demo effect

Postby danorf » Mon Mar 18, 2013 10:35 pm

nativ wrote::idea: :idea: just make a holder for a row of matches and place it in front of your monitor :idea: :idea:


:mrgreen: :cheers:
I Will post in Coding / 680x0 on that topic soon (perhaps tomorrow), as it seems it can interest some people.

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nativ
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Re: Fire Demo effect

Postby nativ » Tue Mar 19, 2013 9:14 am

Well you can either use tricks to do it or base you self in simulation math, probably some thermal dynamics? I looked into that briefly myself.

Lemmings does water well :) and there's a Falcon game 'H20' also water based, or maybe 'wetrix' ( I have that on the DC )
Atari STFM 512 / STe 4MB / Mega ST+DSP / Falcon 4MB 16Mhz 68882 - DVD/CDRW/ZIP/DAT - FDI / Jaguar / Lynx 1&2 / 7800 / 2600 / XE 130+SD Card // Sega Dreamcast / Mega2+CD2 // Apple G4

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nativ
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Re: Fire Demo effect

Postby nativ » Fri Mar 29, 2013 11:59 am

http://youtu.be/qfY-ld-I60M?t=6m55s

here's a fire effect on the Atari XE
Atari STFM 512 / STe 4MB / Mega ST+DSP / Falcon 4MB 16Mhz 68882 - DVD/CDRW/ZIP/DAT - FDI / Jaguar / Lynx 1&2 / 7800 / 2600 / XE 130+SD Card // Sega Dreamcast / Mega2+CD2 // Apple G4

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Omikronman
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Re: Fire Demo effect

Postby Omikronman » Fri Mar 29, 2013 4:37 pm

I made also some fire effects, looking like that:
http://www.youtube.com/watch?v=YyicAxFs-Lc


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