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I use models in Blender to help pose my art, and I thought it'd be useful to have some hints on how things will drape across the meshes - water, jewelry etc. So I thought about it for a bit, tried to make it happen with Material nodes, but ended up with this Geometry Nodes setup, to distribute cones across the mesh, all pointing downhill.
I imagine you could also use this for rendering by changing the instanced mesh to be water droplets or maybe shaggy fur instead of little cones.
One problem that's more accentuated by my low poly mesh is that this uses face normals, not smooth shading normals. I didn't see a way to change this. The "Align Euler to Vector" node is also black magic to me, I'm not sure what it's doing to convert a normal vector into a "Rotation".
I'm using Blender 3.2.0, so I can't guarantee things look the same in other versions.
I imagine you could also use this for rendering by changing the instanced mesh to be water droplets or maybe shaggy fur instead of little cones.
One problem that's more accentuated by my low poly mesh is that this uses face normals, not smooth shading normals. I didn't see a way to change this. The "Align Euler to Vector" node is also black magic to me, I'm not sure what it's doing to convert a normal vector into a "Rotation".
I'm using Blender 3.2.0, so I can't guarantee things look the same in other versions.
Category Artwork (Digital) / Tutorials
Species Rabbit / Hare
Size 1521 x 1200px
File Size 218.4 kB
This is quite a handy setup.
Euler rotation is sequential, "X Y Z in that order", for example. Consider it more like instructions for rotating.
A vector is more like a defined direction from the start in this case. The term is also used for positioning as well.
I made an attempt to simplify the general idea (using version 3.6.9), not to see specifically if it could be improved, but to see if alternative sections or related useful info could be found.
Try this in edit mode, it should help with the Face Normals issue you mentioned:
Select all, then press Alt-N to open normals menu. Select "Smooth Vectors" and adjust the amount in the popup.
This may appear to have a similar visual effect to Shade Smooth, but it affects the points' direction.
Euler rotation is sequential, "X Y Z in that order", for example. Consider it more like instructions for rotating.
A vector is more like a defined direction from the start in this case. The term is also used for positioning as well.
I made an attempt to simplify the general idea (using version 3.6.9), not to see specifically if it could be improved, but to see if alternative sections or related useful info could be found.
Try this in edit mode, it should help with the Face Normals issue you mentioned:
Select all, then press Alt-N to open normals menu. Select "Smooth Vectors" and adjust the amount in the popup.
This may appear to have a similar visual effect to Shade Smooth, but it affects the points' direction.
What I ended up with was an alternative setup that replaces the two "Vector Math: Cross Product" nodes with one "Vector Math: Multiply Add" node and a "Separate XYZ" node.
The "Distribute Points on Faces" rotation output plugs into the rotation input of "Align Euler to Vector".
The Normal output instead plugs into a "Vector Math: Multiply Add" node with the Z setting of Multiplier set to -0.5 and Z setting of Addend set to -1.
The output of that math node goes into the Separate XYZ node, which then only has the Z output plugged into the Factor input of the "Align Euler to Vector" node.
The Vector setting is set to 0, 0, 1.
The "Distribute Points on Faces" rotation output plugs into the rotation input of "Align Euler to Vector".
The Normal output instead plugs into a "Vector Math: Multiply Add" node with the Z setting of Multiplier set to -0.5 and Z setting of Addend set to -1.
The output of that math node goes into the Separate XYZ node, which then only has the Z output plugged into the Factor input of the "Align Euler to Vector" node.
The Vector setting is set to 0, 0, 1.
Interesting, that definitely cuts down on the nodes, I just went with the cross products cause I know how they work (first one makes a vector along the contour height line, second one combines that with normal vector to make a new tangent that points downhill)
I guess that's doing something like rotating the normal 90 degrees in a plane that has +Z on it. I'm familiar with Euler angles but don't know what the node's internally doing when you mix vector/rotation inputs.
I guess that's doing something like rotating the normal 90 degrees in a plane that has +Z on it. I'm familiar with Euler angles but don't know what the node's internally doing when you mix vector/rotation inputs.
It's intended use is similar to a mix input, with the factor dictating how much of the rotation is inherited from the Rotation input compared to the Vector input.
Your setup is a bit odd and doesn't use that, but it gets pretty much the same result. I have never used or even heard of this node before today.
The vector input for X Y Z can be treated as "weight for pointing in those directions". The resulting vector rotation is like an average of the axis inputs.
Rotation input and factor input can be assumed to work the same as in a mix node.
Your setup is a bit odd and doesn't use that, but it gets pretty much the same result. I have never used or even heard of this node before today.
The vector input for X Y Z can be treated as "weight for pointing in those directions". The resulting vector rotation is like an average of the axis inputs.
Rotation input and factor input can be assumed to work the same as in a mix node.
Yeah, swapping out the cone placement for something a little more organized is definitely useful for producing different effects. I wonder if you can safely do a recursive node setup where it adds a little line 'downward' then starts the next one from the previous one's origin, or if that makes an infinite loop.
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