View Full Version : GIMP Brushes Question

03-03-2012, 08:49 PM
I am trying my hand at making some mountain brushes for gimp. My goal is a generally right hand shaded/steep set of mountains (large variety desired for a major overland work) with a shallower unshaded side to the left. I can get the left to look good, but can't seem to get the right side to shade. By shade I do not mean fully tinted, I mean shadding lines or crosshatching. The problem is the tend to form what looks like pyramidal steps. If I use blurring or transparency to achieve the effect I want, it renders as a solid color after I save it as a brush. I've tried drawing them on every possible type of layer, but the right just wont turn out.

I seem to be at an impasse with this. The attached image is the mountain base form I am working with. This one gives a good outline shape, but once I add several 1px wide shadow lines they either show up as pyramid style stairs, or fully shaded. The sample shows blurr effects, and the "stair step" effect I am talking about. The effect I want is a hand drawn shading of the darker side.

I'm not sure if I am up against a software limitation or what. I am fairly new to the advanced features of gimp, and have never tried my hand at brushes before.

The zip file includes the gimp xcf file that includes some layers showing various hatch stiles I have tried.

I can't seem to get it to shadow right. It is either fully opaque, or fully transparent. If anyne knows of a good tut covering this, or could offer some advice, I would appreciate it.


03-04-2012, 02:02 AM
Sorry but my Photoshop skills are limited and I know nothing about Gimp, But there are a lot of great artists here who use it, I'm sure someone can help you.

03-04-2012, 02:16 AM
"fully opaque, or fully transparent"? You mean it looks ok until you save it as a brush at which point it does this?

RobA has a tutorial on making rotating brushes but I'm not sure if that will help.

03-04-2012, 02:49 AM
Jax- Yes, the problem only shows up after saving(and used) as a brush, and then only the right side does the trans/opaque issue (which issue is dependant upon the the type of shading I including in the drawing to begin with. The sample just shows two types I have played with. Using "shade lines" (1 px wide black lines in various angles/places) gives either pyramid stairs or solid black upon insertion, using blur goes solid black, shadint the whole brush face sometimes goes all transparent) I am just lost here. (and going bald at this rate!)

Edit: Ive been following tuts by RobA and Gidde and Ironmetal250 as I work on this.

03-04-2012, 07:49 AM
Not quite sure whts going on...when I get back from BFast(say 45 minutes), I will try to knock up an example or two to see what your have happening.I typically stick with real shading and use the smudge tool, so mine mountains will look quite different from the approach you are going for..

03-04-2012, 09:50 AM
@JF - I looked at your ISO tut for the smudge drawn. (Excellent work btw) It gives a nice watercolor or filled look, but in this case I am going for a "hand drawn" or "sketched" look. I have managed to take some brushes made by others and reverse the images (laborious) to get the feel I was after, but I would still prefer to generate my own.

I think that the issue has to do with the ppi settings for the drawing vs the ppi for the image. Obviously a brush at 100 ppi will have less detail when used in 70 ppi drawing, and if vise versa the brush will look blockier. But even when drawn at the same density it just doesnt look right. Still becomes solid in appearance. Ive tried using the brush on a variety of layer types (Normal, Overlay etc.) and the result is usually an opaque right side. Oddly enough, the modified brushes work OK, and upon close examination of the brushes (Opened as image file) the DPI is similar to what I am using for mine (only off by a couple %) so I am sure it is something in my settings now. BUt I still cant find it.

03-04-2012, 11:32 AM
I took a look at your file and have a few pointers.

1) You seem to be drawing your mountain with the pencil tool. This creates unaliased (hard edged) lines. I think you would have better luck with the paintbrush tool.
2) Your image is RGBA. If this is saved as a gimp brush (gbr) file, it will end up exactly as it looks - i.e. black on transparent, regardless of the paintbrush colour you are drawing with. This is the mode you want to use when creating multi-coloured brushes. If you add a white background and change the mode to greyscale (Image->Mode) then your saved brush will have transparency where the image is white and be fully opaque where the image is black, with a 50% grey being 50% opaque. This brush will also paint in the current foreground colour. It will all be ONE colour, however.
3) When using any brush, if you use it with the pencil tool, it will be hard edged (i.e. anything less than 50% opacity will be transparent, anything more will be solid). That seems to be the issue when you say "it renders as a solid color after I save it as a brush".

Hope those tips help!

-Rob A>

03-04-2012, 12:21 PM
Simply tell me where you want it and I will build shrine unto you! That RGB vs greyscale thing was the whole issue! All Hail The Mighty RobA! (by the way just added GURM and hats off to those of you who made it great as well!)

EDIT: Tried to rep ya for the fix but apperently I already did in relation to one of your tuts today....sooooo...more comming soon!

03-04-2012, 12:40 PM
Hehe, once again the resident master of us Gimps comes through :)