Strawberry plant => Looks like a plant.
Strawberry plant with strawberry growths on it => Looks like a plant with berries.
Doing either is easy, but doing both will be difficult. plant_crops, plant_garden and plant_standard have 34, 57 and 52 plants respectively, for a total of 143. Subtract the 31 trees in plant_standard, and you have 112 crop tiles. These tiles would be set with PICKED_TILE and use slots 0-111. Then you have the plant-with-berries tiles. To get those, I think you would change the GROWTH_PRINT of the berries to some unique tile not used by any crops. So assuming every plant has a minimum of 2 tiles, you'd use up slots 112-224 for the plants with growths. That'd leave you with 32 slots for modded plants.
On one hand, this is an overestimation because not all plants will have 2 tiles. On the other hand, it is an underestimation because you cannot use tiles 0, 32, 205, 247 or 255 for plants. Why? I don't know. I wrote myself a note in GemSet that I can't do that, and I'll trust my past judgement on that.
A good workaround for this problem is what I did in GemSet: Have the normal part of the plant be whatever color you want, then have the growth be a see-through background like barrels in most tilesets. The berries on your strawberry plant would be green, then turn red once they're read to be picked. I believe you would do this by setting the GROWTH_PRINT tile to 0 but changing the background color. To achieve the see-through part and keep the shading, you would convert the berries to grayscale then use an image editor to convert grayscale to transparency. In GIMP, I believe you can do this with
layer masks. This would be a lot of work, but it would be well worth it as it would free up roughly 112 tile slots for modded plants.
Strawberry plant, picked => Looks like strawberries.
I'm not positive on this, but I think you can make an item override for that. In GemSet, every plant has the overrides:
[OVERRIDE:96:B:FARM_PLOT:FarmPlot::4:224]
[OVERRIDE:96:I:PLANT:PLANT::4:224]
With the first being the crop and second being the picked plant. Both have the same image in GemSet but I think you could easily separate them. Keep in mind, there are some quirks to which picked plants use growths and which use the entire plant. Button describes this
here.
BTW: You can do overrides for corpses, so in theory you can make 256 custom corpse-tiles.
Hey, that's pretty awesome! I think I'll try that in future projects.
The first number behind PLANT_GROWTH, I just leave that empty. What does it change in your set?
Erm...in retrospect, it's probably unecessary for me to be adding the 0, 1, 2 and 3. I do that to catch every possible "layer" a growth could be in (like I described above). If I excluded that number like you, I think it would act as a wildcard and handle it for me.