I’m still very new to blender, and for the death of me cant figure out how is best to resolve this issue I’m running into, maybe someone can provide a step by step way to achieve this? im still a noob!
I’ve added a hair particle property to the majority of the tennis ball, apart from certain white areas which are slightly engraved to show the ‘stitched area’. What Im trying to do is add a white logo (the turtle illustration) to my tennis ball and I want this logo to look similar to the white ‘stitched area’ of the tennis ball, so that this logo doesn’t have hair coming out from it and is instead ‘bald’.
At the moment I have added a shrink wrap modifier to the logo layer, and this is basically just projecting the logo on top of the tennis ball, which means the hair particle properties are still coming up and out through the logo, which isnt the effect I want. I have a rough idea that maybe I can apply a vertex group to the density/length of the hair in the particles settings, which Is how I got the bald ‘stitched area’ bit, however cant seem to figure out how to get this to also work for the logo area
Adding the logo area to group2 will make it also be bald. Or in your case remove it from group2. There are a few vertices along the topology seam at the top of the ball that are easiest to get at from the inside.
I often prefer to do the vertex group editing in edit mode rather than Weight Paint mode. Either way you are working on the same vertex group.
Change to the Lasso Tool by holding down the LMB and releasing it once the cursor is over the wanted icon…
then select and remove the wanted vertices from group2
Remember - you can do this in Weight Paint if you prefer. Set the weight to zero to remove.
You need to press m > Merge by Distance to get rid of some of those double vertices along the topology seam. And probably merge (M > Marge at Center) pairs to fix the rest of them.
Oh nice, this is really helpful thanks! but is it possible to make the bald area follow the white lines of the illustration? or does it have to be a circle/ lasso shape around the illustration?
Doing this in my head, so not 100% sure. If the logo is on the ball, it will have hair (unless you have enough geometry/vertices to be able to deselect the verts perfectly along the lines of the logo. My idea (though a little bit long) is to trace the lines of the logo, with verts from a new object, or curve if you like, then shrinkwrap that to the ball, and parent it. You will have to give it some thickness, so extrude the verts or bevel the curve. Make the new “logo” object into a collision object, enable “hair dynamics” on the ball hair particles, and (in theory), the hair shouldn’t come through the logo.
You could cut around the logo with the knife tool, then select inside that new cut, rather than my free form selection. That will make it far more accurate.
Blender has a issue with going over (‘bleeding’ over) the seams with particles. So you may need to leave a gap of a couple times the line thickness.
You can use illustrator / inkscape to convert the image outline into a curve, bring the curve into blender, convert into a mesh and extrude it Up/Down. Then use that shape to do a boolean cut. Its another possibility - IF you have either app, and are familiar with vector work. Or you could use blender to trace the outline with mesh or a curve, then convert (if curve), extrude, boolean etc…
Blender has an addon that comes with it called Bool Tool. Which you can activate in the Preferences > Addons. It will be in the 3D window ide (n) panel. It gives you a slice option the standard bool tool is missing. Slice cuts a line rather than cutting out a chunk. Useful if you have an outline to boolean with.
You can use your texture to control directly the density of the particles (no need to use vertex groups).
Follow the instructions in that thread.
You will find a few problems though.
1 you have to reverse the colours of your texture with the colour ramp in the texture tab so that the turtle is black and the background white, (white means full density and black none.)
2 also clip the colour ramp a bit.
3 you will also find that your turtle has very thin lines so the effect is not that noticeable it will leave them bald but with thicker lines it would show better (and maybe more general hair density and less length and randomness in the hair)
I did not upload the file because it is too big but these screenshots should help:
@DNorman you are an actual wizard! After spending hours trying to figure this out I’ve actually managed to take a few steps in the right direction, this was super super helpful thank you so much! I’ve also altered the logo to a new one which is a bit thicker, so it works nicer!
Butttttt theres still a tiny tiny bit of tweaking I could do with getting a bit of help with! So I managed to create a texture which now controls the density of the hair directly, however:
My texture is repeating for some reason? I think its something wrong that I’ve done in the UV mapping bit? I only want the logo to appear once on the top of the tennis ball, and I can’t seem to tweak the uv mapping in any way to get this to work? any tips here?
The ‘bald’ logo area should be white so its the same as the white lines around the other bald parts of the ball, at the moment its black.
The rest of the tennis ball with the hair needs to be green!
Thanks again in advance! Link to the updated blender file is below! :)))
You are using the black image with alpha in the shader editor so using the alpha as factor for the colour mix node will assign green to the alpha and white to the black.
The uv’s need redoing, here I selected only the top of the sphere in edit mode and unwrapped it from the top view with project from view bounds. Then I did select invert ( “Ctrl I” in edtit mode) and unwrapped the inverted selection, I moved the inverted selection away from the image in the UV mapping window. I also re scaled the top Uv’s a bit.
It looks a bit messy but it works! The idea is that only the top faces where you want the logo are ontop of the image in the Uv editor.
You also need to set the mapping in the properties - texture tab to clip.
Watch out there are 2 mapping tabs this one is under “Image settings”
There is another one further down that sets the mapping to UV in the screenshot you can see both.
Again, thanks so much for all the help here guys! managed to achieve what I set out to do and feel like I learnt a lot of cool tricks I can apply to future projects! S
I did not nit pick your modeling as the question was about the texture and shader, but your ball has loads of double verts and the topology is very dense. (That is why I did a lazy UV unwrap)
Next time I recommend you keep the polycount fairly low and do not apply the subdivision modifier (until you have too, like for exporting the final model.)
That way you can make a nice seam and unwrap it properly.
