CreatingShieldIconsInGimp

This is a quick summary of how I created two segment shield icons for the HUD.

I'm writing this down so I remember how to do this, because me not being an artist, it took me ages to figure out how to do this and I don't want to go through the frustration of rediscovering it!!!!

Programs I used:

• GIMP 2.8
• apngasm 3.1.6

Create Ship Image

1. (if necessary) create a new canvas 112x93
2. Import a top down image of the ship & centre it
   • so far I've grabbed the existing shield anim frame 0
   • might be able to grab other ships by
     1. setting shield anim to be FSO generated
     2. DISABLING shields (or the auto-generated shield bars may overlap the image)
     3. screenshot'ing the HUD
     4. converting the image to greyscale (TBC how best to do this!)

Create Shield

1. Using fuzzy select (with zero threshold) select the area outside the ship image; then invert selection
   • If necessary modify the selection to better fit the ship, e.g. using the oval select (additive) to round out an irregular shape
2. Select -> Grow... by 10 (? try 11) pixels
3. Select -> feather set to 2 pixels
4. Create new layer (black background) & select the new layer
5. Bucket fill: white
6. Select -> Shrink... by 3 (?) pixels
7. Bucket fill: black (leaving a mostly 1 pixel full-white outline)
8. Select -> Grow... by 2 pixels
9. Filters -> Blur -> Gaussian blur; aspect locked; 3 (?) pixels
10. Filters -> Artistic -> Softglow; 9 (?) pixels
11. Use colour select to select all the fully black regions (outside & inside shield); then invert selection
12. Layer -> Mask -> Add Layer Mask... using the current selection
13. Confirm you can clearly see the ship and the shields don't overlap the ship (unless you really want them to!)
14. STOP EDITING THE LAYER MASK (I've accidentally done the next steps to the layer mask TOO MANY FREAKIN TIMES!)

Split Shield into Segments

(this assumes fore/aft two segment shields; adapt as necessary for more segments)

1. through the middle of the the shields; create rectangle selection 3 pixels high & shield width, then bucket fill full black (try 5 pixels to give more gap between the segments?)
   • ensure bucket fill has "Fill Whole Selection" selected (*sigh*)
2. at the end of each shield (4x ends) create rectangle selection, 4 pixels high & shield width (1 pixel into black space; the other 3 over the shield)
   • should have 4x small rectangles
   • use additive select (hold down shift while selecting)
3. apply the gaussian blur filter (3 pixel, width & height locked)
4. duplicate the existing shield layer
   • rename the layers to fore & aft if you wish
5. In the aft shield layer, select the XXXX
   • select / cut / etc DO EEET AND WRITE ABOUT EEEET
6. export image (all layers) as png (or one at a time; whatever floats your boat)
7. use apngasm to create APNG image
   • apngasm -o shipname_icon.png ship.png fore.png aft.png
   • note the order; that's what FSO expects
8. test in FSO

WASH, RINSE, REPEAT

TODO: figure out if there's any benefit to creating an ani instead of an apng (maybe uses less ram/texture memory? since apngs auto-expand to full 24bits per pixel?). On the other hand, creating an ANI seems like a PITA...