Population question

[Syntrifid]

Hi All
I have a question about populations. Say I add the grass clump as pop and want to have various sporatic patches of grass throughout the populated area or breakup the straightedge rectangular borders of the area. I am thinking the Density shader would be the way to go but at present all I'm getting is when the density shader is applied, the grass all just disappears. if I invert the shader it is visible again.
Is density shader even the appropriate way to go for this? and does anyone have any decent settings for doing this or point me in a direction for getting the result I'm describing?
OK maybe that's two questions 
thanks for any info you can provide.
Jack

[EmDee1]

I assume you have managed to get yourself an area full of grass clumps.
Now then: go to the object tab and select "pop grass clump".
Tick: "use density shader" and left click the button with the three ...
Then: create new shader: surface shader: image shader.
The image shader should act as a mask to get the grass-clumps in the areas you want:
white area will produce grass-clumps, black area: no grass-clumps.
So for practice you can make an image of a simple circle-shaped black area in the center of a white color, use Photoshop or a similar program.
When you've imported the mask-file: tick the three ... again and choose: "go to image map shader".
There you choose as your projection type: Plan Y.
Tick: position center.
Size: same size as in the "pop grass clump" where we started, 1000 x 1000 for example.
Hope this will help.
Greetings.

[EmDee1]

....... and also: the numbers you enter as the position of the image map shader (the mask file),  should be the same as the numbers you enter as the position of the "Area centre". (in our "Pop Grass Clump" window, where we started)...... Sounds a bit complicated, but it works well this way!

[Syntrifid]

Thanks for the reply. Yes, I have no trouble getting the population in there or activating the density shader function itself. But I was trying various procedural type shaders. So I should go with an image map shader rather than one of the various procedurals.
Thanks again, I'll give it a shot.

>>>Sounds a bit complicated, but it works well this way!<<<

Hey, no actually that sounds perfectly logical 

[§ardine]

Well I took too long getting this together but I'll post it anyway.

I've attached a tgd that has 3 examples you might try. just hit populate after attaching the shader of your choice.

Cloud fractal Shader v3 - this, imo, is the easiest way to go as it has the Density tab where you can adjust the contrast and coverage in one spot.
Distribution shader v4 - this gives you more control over your population. be sure to bring the coverage down if it is putting too many instances in your scene. You will also want to edit the Fractal breakup shader here more than likely; setting the scale to taste.
Image map shader - Input your own gray-scale (not included)  image. Anything white will be populated, black will not and gray will be in between. be sure to set projection to Plan Y and the position and size to the same as your population.

[attachurl=#1]

[EmDee1]

I'm eager to examine the first two with the procedurals, so far I've only worked with the image map shader.
Thanks §ardine.

[Syntrifid]

Thanks for the examples! Not too long at all.  All replies are most welcome!