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Thread: Random Density Map GIMP Script

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  1. #1

    Info Random Density Map GIMP Script

    As hinted here I have been working on a gimp script to draw with the active brush using a "density map" to determine the probability of painting.

    Attached is a zip. Just drop it in the gimp script directory.

    Here is where it registers in the menu:
    menu.png

    Do use it in the most basic way, create a probability density map.... a layer where back will have a 0% chance of drawing and white will have a 100% change of drawing:
    map1.png

    Create a new layer (it must be the same size) to draw on with the current brush.

    Here is the dialog:
    dialog.png

    and one result with a red Hexagonal 21 px brush, and set it at 100% Density, Spacing of 21 px, and no Jitter:
    1-nojitter.png

    (more examples following...)
    Attached Files Attached Files

  2. #2

    Post

    Using the same Density map, here are more results:

    Setting the density to 50% will make white only have a 50 chance of drawing. Here again with no jitter:
    2-nojitter_50percent.png

    And back at 100%, but with a jitter of 1. The jitter value is a scale of the spacing parameter, for randomly displacing the x&y directions, to get rid of the grid look:
    3-jitter.png

    The scrip draws left to right and top to bottom, to work with isometric image brushes, like the trees posted:
    4-trees.png

    And using the "invert" check will invert the map (black = 100% chance and white = 0% chance):
    5-trees_invert_map.png

    (cont...)

  3. #3

    Post

    The other option is less useful for mapping but might have some artistic uses...

    You can use a map with transparency, and it will use the alpha as the density map, and the colour as the colour to paint with.

    Here is such a density map:
    map2.png

    and the result, using the hex brush again:
    map2_result.png

    Enjoy!

    -Rob A>

  4. #4

  5. #5

    Praise

    Excellent and useful stuff.

    S. John Ross Ghalev
    Who Dat? Games Fonts Uresia

  6. #6
    Community Leader jfrazierjr's Avatar
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    The drool is running down my chin as I type. This is GREAT. I can't wait to try it out.

    Joe
    My Finished Maps
    Works in Progress(or abandoned tests)
    My Tutorials:
    Explanation of Layer Masks in GIMP
    How to create ISO Mountains in GIMP/PS using the Smudge tool
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    Unless otherwise stated by me in the post, all work is licensed under a Creative Commons Attribution-Noncommercial 3.0 United States License.

  7. #7
    Guild Artisan su_liam's Avatar
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    Cool. I'll have to try this. It looks like you might be able to use the alpha-and-color option to cause interesting variation in tree(or mountain or whatever) color. For instance, with trees, create a layer with a narrow variation of green shades. (Possibly use a greyscale fractal and gradient map with a narrow gradient(say dark green to light green)).

    Another idea I have is to make an initial color layer that varies only in hue and saturation, and apply a variation in value by multiplying with the shaded relief from an HF.

    Then you paint in your desired forest density in alpha.

    Might be a good way to add an interesting forest texture to a shaded relief map.

    I was initially thinking of using top-down trees for a realistic look, but I think this might work best all symbolical, with iso trees simply as a symbol saying, "forest here."


    If nothing else, this is making GIMP look like a more and more viable alternative to CC for "symbol"-type maps.
    Last edited by su_liam; 07-07-2008 at 01:46 PM.

  8. #8

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    One limitation is that it doesn't respect active brush scaling, so all images are drawn at the original scale of the selected brush. Initially, I hoped to have an options to paint smaller versions based on the density map, but dynamic brush scaling isn't exposed in the scripting API (yet).

    -Rob A>

  9. #9

    Question Is there any way to make it draw on another layer than the density map?

    Quote Originally Posted by RobA View Post
    Using the same Density map, here are more results:

    Setting the density to 50% will make white only have a 50 chance of drawing. Here again with no jitter:
    2-nojitter_50percent.png

    And back at 100%, but with a jitter of 1. The jitter value is a scale of the spacing parameter, for randomly displacing the x&y directions, to get rid of the grid look:
    3-jitter.png

    The scrip draws left to right and top to bottom, to work with isometric image brushes, like the trees posted:
    4-trees.png

    And using the "invert" check will invert the map (black = 100% chance and white = 0% chance):
    5-trees_invert_map.png

    (cont...)
    Is there any way to make it draw on another layer than the density map?

  10. #10
    Guild Adept Seraphine_Harmonium's Avatar
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    This is a great idea. I noticed though, that you have trees in various colors. How do you get this to happen?

    When I first tried to use this, I was using transparent brushes, which I have found doesn't work if the density is greater than the very sparse. I ended up layering color behind one, merging down, and making a brush from the clipboard, but the trees all look identical that way. In your example there is at least color variance. Is this a difference in how I am implementing the script, or did you recolor them afterwards?

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