Sorry your browser is not supported!

You are using an outdated browser that does not support modern web technologies, in order to use this site please update to a new browser.

Browsers supported include Chrome, FireFox, Safari, Opera, Internet Explorer 10+ or Microsoft Edge.

Geek Culture / question about battle squadron graphics (amiga)

Author
Message
Phaelax
DBPro Master
22
Years of Service
User Offline
Joined: 16th Apr 2003
Location: Metropia
Posted: 25th Jan 2011 19:52
Link
Here's a video if you don't know the game or can't remember it.


Anyone know how they might have done the invisible guys? You can somewhat catch them between 1:15-1:22. As you can see, they're not completely invisible. It's kinda like the invisibility the Predator uses, how it distorts the background almost like a bubble laying on top. Far as I'm aware, the Amiga didn't have alpha channels like what I would likely use to do the same effect today.

"Only the educated are free" ~Epictetus
"Imagination is more important than knowledge..." ~Einstein
Back to top
Profile PM Email Website
Insert Name Here
18
Years of Service
User Offline
Joined: 20th Mar 2007
Location: Worcester, England
Posted: 25th Jan 2011 20:20
Link
Could they have just manually moved and stretched the pixels manually?

"Sticks and stones may break my bones but words will never hurt me." That's a bit like saying Hey bullies! So yeah, this words thing isn't working, but I'll tell you what will
Back to top
Profile PM
Fallout
22
Years of Service
User Offline
Joined: 1st Sep 2002
Location: Basingstoke, England
Posted: 25th Jan 2011 23:03
Link
I agree with INH. These old 2D games are all about drawing groups of pixels. It'd be very simple to, instead of drawing a bitmap pixel by pixel, sample the pixel of the ground where you're going to draw, and redraw it left or right, or similar to create a distortion effect.

In 3D I guess you'd use a shader, although there's nothing to stop you using the same 2D technique. You could lock the back buffer maybe and write some uber fast pixel moving code.

Back to top
Profile PM
Van B
Moderator
22
Years of Service
User Offline
Joined: 8th Oct 2002
Location: Sunnyvale
Posted: 26th Jan 2011 00:09
Link
The other thing to bear in mind is that there was just a single block of memory, so screen buffers, images, were all accessible. I swear GFA Basic on the ST had a faster POINT command than DBClassic.

Health, Ammo, and bacon and eggs!
Back to top
Profile PM Email
Kevin Picone
22
Years of Service
User Offline
Joined: 27th Aug 2002
Location: Australia
Posted: 26th Jan 2011 01:04 Edited at: 26th Jan 2011 01:46
Link
I haven't looked at this game for years. There's no alpha channel in Amiga. So translucence effects are generally achieved by palette manipulation (classic examples are games like james pond / robocod) . So one approach might be to use the mask and write to the extra bit plane with the palette carefully set.

but I suspect it might just invert the mask and shift the bits behind the image. Which would displace the background pixels as if light is being bent by an invisible foreground object.

Pulling pixels from planar buffer would be one of last resort. 68000 don't have barrel shifters, so the further you shift a bit the slower it gets.


Hmm, I wonder what's coming in 2011?
Back to top
Profile PM Website
Back to top

Login to post a reply

Server time is: 2025-05-30 10:07:22
Your offset time is: 2025-05-30 10:07:22