I need to totally rewrite this to handle the change to how shadows are handled. I've edited some of the lines but there may be references still in there.
Tutorial One - Creating Brushes
1.) Open a new document in your favourite raster paint program.
Doesn't really matter what size - the program will shrink your brushes to a usable size - but obviously be aware that the larger you make your brushes the greater the filesize and also the more detail will be lost when they are shrunk right down.
2.) On a new layer, draw the outline of a tree in a dark colour. You don't have to use the pencil tool but don't make the edges too soft at this point. Make this the largest brush you intend to have.
The program will work better if all brushes are roughly the same width and height, but a small amount of variation won't kill it - the program works from the largest brush so any that are smaller mmay have more space around it when placed.
If you are pressed for time or just a rebel and don't intend to make a mask to go with the tree, make sure you colour in the foliage of the tree so the program knows where to clip. It doesn't have to be opaque but needs to be above a cerain opacity (which is quite low... maybe 10% or something) so the program doesn't just ignore it.
Any other tree brush that you make for the same set, position the base of the trunk in the same position.
3.) With the largest tree being displayed, crop down your image so that any excess space is removed from the brushes.
My image size for the Vaniyan shaded brushes after cropping is 100 x 119 px.
4.) Copy the tree outline to a new layer and colour in the foliage to make your mask. Use a sharpen filter to remove some of any softness around the edge.
I colour my masks white but it isn't essential - the colour is unimportant. The sharper edge on the mask makes for more precise clipping when one tree is overlaid over another. The mask layer of a forest is also useful if you want to layer a colour beneath the forest on your map or put a stroke around the edges for a bold statement.
5.) If you took my "don't make the edges too soft" instruction when drawing the tree outline too literally, then feel free to soften it a little now with a small blur.
6.) On a new layer, shade the same side of the tree as your shadow will fall.
7.) On another new layer, shade the other side of the tree.
8.) Open a new document and draw a shadow for your tree. Crop it so that there is no unneeded space around the shadow. You don't need a shadow brush if you don't want but if you do you can draw as many different ones as you like.
9.) Save all your layers individually to .png files:
- Shadow brush filenames need to begin with "shadow". E.g. "Shadow1.png" (you can ignore capitalisation on all the filename instructions)
- Tree brush filenames need to begin with "tree". E.g. "Tree1.png"
- Mask brushes need to begin with "mask". E.g. "Mask.png" Make sure you name any mask files correctly though if your forest has more than one tree. An incorrectly named mask could assign it to the wrong tree and create odd clipping in the forest.
- Shade brushes are the most awkward to name:
- First shade brush - same side as your shadow) If your forest only has only one tree brush (like the TreeThing defult brush set) or your shade brush can be used for all trees you can simply make sure your shade brush file begins with "shade" E.g. "Shade1.png"
- If your forest has multiple trees of varying shapes then each shade needs to be assigned to the right tree brush. Do this by including the name of the tree in the filename and following it with an underscore character "_" E.g. "Shade1Tree1_.png" (The underscore is a bit of a speed method to save me having to put more filename parsing in. You can safely miss this off if you have less than 10 tree brushes. Any more and placement errors will occur without it.)
- Second brush - opposite side to shadow) The second shade brush needs to be named in the same way as the first but have either "_r", "rev", "reverse", "reversed" at the end of the filename. Note the underscore if you simply use the letter "r" (in case someone uses some odd file naming system and the program mistakes the end of a word and thinks it is reversed) E.g. "shade1_r.png" or "shade1_tree1_rev.png" or even "shade10Tree10_thisnamestillcountsalthoughitisoddre verse.png"
And that's it. You can add as many shade brushes as you like to a single tree. Same with shadows. You don't have to shade both sides of the tree if you don't want (although that will stop you shifting the light source effectively) You don't need to actually have anything other than a single tree brush to use the program. No shading needed. No shadow. No mask. But the forests generated will be much more effective with them.
Example Image to follow...