Bob/Icon Opacity?

Brick Nash · 18 April 2018, 14:43

I'm trying to figure out if there's a way to gradually reduce or increase a Bob or Icon's opacity so that I can get a gradual fade in and out effect?

I've had a scan through the manual and all I can really find is the FADE command for the entire screen, and even the I can only get a Fade out and not a Fade in.

I could just do an animation for the Bob with images of the varying stages of pseudo fade in/out, but this seems a bit clumsy.

Any suggestions?

Thanks!

Samurai_Crow · 18 April 2018, 16:45

Blending via alpha channel is unsupported by the Amiga chipsets. There's another way If you're using a spread palette.

Brick Nash · 18 April 2018, 16:49

Thanks.

Could you elaborate on this "Other way"?

Samurai_Crow · 18 April 2018, 19:21

There's a command, something like "limit planes" or "limit mask", that will cause "paste bob" to only blit some of the bitplanes and leave the rest intact. That can be used to do a sort of blending effect.

Brick Nash · 18 April 2018, 19:56

Cool thanks! I'll look into it.

adrazar · 20 April 2018, 14:58

This sounds like a fun challenge! I would like to give it a try, but could use some additional technical info first:
1. How many colours (i.e. bitplanes) does the bobs use?
2. How many colours does the backdrop use?
And finally, 3. does the bob move while fading or is it at rest?

Brick Nash · 23 April 2018, 13:03

Hi adrazar, I actually managed the same effect by using the Fade instruction for the screen. I just wanted a part of the background to look like it was glowing so I had planned to fade in and out a large bob over the top of it, but the Fade worked nicely!

18 April 2018, 14:43	#1
Brick Nash Prototron Join Date: Mar 2015 Location: Glasgow, Scotland Posts: 411	Bob/Icon Opacity? I'm trying to figure out if there's a way to gradually reduce or increase a Bob or Icon's opacity so that I can get a gradual fade in and out effect? I've had a scan through the manual and all I can really find is the FADE command for the entire screen, and even the I can only get a Fade out and not a Fade in. I could just do an animation for the Bob with images of the varying stages of pseudo fade in/out, but this seems a bit clumsy. Any suggestions? Thanks!

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18 April 2018, 16:45	#2
Samurai_Crow Total Chaos forever! Join Date: Aug 2007 Location: Waterville, MN, USA Age: 49 Posts: 2,186	Blending via alpha channel is unsupported by the Amiga chipsets. There's another way If you're using a spread palette.

18 April 2018, 16:49	#3
Brick Nash Prototron Join Date: Mar 2015 Location: Glasgow, Scotland Posts: 411	Thanks. Could you elaborate on this "Other way"?

18 April 2018, 19:21	#4
Samurai_Crow Total Chaos forever! Join Date: Aug 2007 Location: Waterville, MN, USA Age: 49 Posts: 2,186	There's a command, something like "limit planes" or "limit mask", that will cause "paste bob" to only blit some of the bitplanes and leave the rest intact. That can be used to do a sort of blending effect.

18 April 2018, 19:56	#5
Brick Nash Prototron Join Date: Mar 2015 Location: Glasgow, Scotland Posts: 411	Cool thanks! I'll look into it.

20 April 2018, 14:58	#6
adrazar Registered User Join Date: Feb 2017 Location: Oslo Posts: 90	This sounds like a fun challenge! I would like to give it a try, but could use some additional technical info first: 1. How many colours (i.e. bitplanes) does the bobs use? 2. How many colours does the backdrop use? And finally, 3. does the bob move while fading or is it at rest?

23 April 2018, 13:03	#7
Brick Nash Prototron Join Date: Mar 2015 Location: Glasgow, Scotland Posts: 411	Hi adrazar, I actually managed the same effect by using the Fade instruction for the screen. I just wanted a part of the background to look like it was glowing so I had planned to fade in and out a large bob over the top of it, but the Fade worked nicely!

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