Coloured fading circle

[GlasBeard]

Hi. Pretty new to using Gimp, or in fact any designer software, and slowly getting used to some of the functions.

I need to be able to draw a circle which starts off full opacity and fades gradually as it goes round. So for example, at 0 degrees it’s bright red, and but the time the circle comes back in itself, it’s fully transparent...if that makes sense 

I’m sure there will be a simple way to do this, but can’t work it out.

Thanks in advance for any help.

Barry

[rich2005]

Not as straight forward as you might like.

Start off with the circle on a transparent layer (make life easy for yourself and keep it symmetrical)
Add a white layer mask to that layer Layer -> Mask -> Add Layer mask. Then working on the layer mask.
Apply a black to white gradient across the layer mask. Use the center point slider to heavily bias on the black side (lots of white)
Apply Filters -> Distorts -> Polar Coordinates.

If ok Layer -> Mask -> Apply otherwise, back off and try adjusting the gradient, repeat

example: https://i.imgur.com/OIIEhNr.mp4

[GlasBeard]

Brilliant. That does look easy enough, will give it a try. Thanks for your help, and the video. Amazing. Cheers.

[Ofnuts]

1. Circular selection
   
2. Blend tool, shape: Conical asymmetric, Gradient: FG to transparent
   

   

For more complex effects you can use the conical gradient on the mask:

   

[GlasBeard]

Thank you, will try this also. First suggestion worked so now have a couple of options. Cheers.

[GlasBeard]

So trying to do this, and perhaps looking in the wrong places, but where is:

1. Blend tool, shape: Conical asymmetric, Gradient: FG to transparent
   

I don't seem to have a tool called Blend, or a menu option...

Thanks, and apologies, very new to this, so still learning.

thanks

Edit, ok, so think I found this under the gradient tool, so can select Conical asymmetric, and FG to transparent, but my result essentially cuts the circle in half, colour at top and transparent at bottom.  Am I missing a step?

[rich2005]

It is actually a more efficient method

Check in the gradient drop down that you do not have FG to BG hard edge set in case FG to Transparent did not 'fix'
You also need to check after making any adjustment to the gradient. It then becomes 'custom' - easy to miss.

Then it is start in the center and draw the gradient out-over. The gradient can go in either direction. Adjust the center point slider to get the desired effect.

Again assuming a circular ring rather than a circular disk, method is the same for both.

Just about make the 60 second limit https://i.imgur.com/JCy0XOV.mp4

[GlasBeard]

(07-28-2020, 01:13 PM)rich2005 Wrote: It is actually a more efficient method

Check in the gradient drop down that you do not have FG to BG hard edge set in case FG to Transparent did not 'fix'
You also need to check after making any adjustment to the gradient. It then becomes 'custom' - easy to miss.

Then it is start in the center and draw the gradient out-over. The gradient can go in either direction. Adjust the center point slider to get the desired effect.

Again assuming a circular ring rather than a circular disk, method is the same for both.

Just about make the 60 second limit https://i.imgur.com/JCy0XOV.mp4

Brilliant, thanks for the video as that helped so much.  It worked for me, so feel quite accomplished.

thanks again :-)