Meshes are an excellent way to add natural and organic deformations to characters. In this quick tutorial, we’ll cover the basics of setting up a mesh, connecting it to bones, and setting up weights so that it deforms properly.
Get started by dragging and dropping your PSD into Nima. You can grab our dog character here.
Now hit B to activate the Create Bone tool and start drawing some bones. Your first click will create a root bone; every subsequent click will create a bone.
You can select your bones and change their size to make them better match the scale of your character. Note that we pressed F on the keyboard to zoom and center on our selection.
Hit T when you’re done to switch back to the Translate tool. Move the joints to make your bones roughly the same length. Try turning on Freeze Joints to make this process easier. Having Freeze Joints enabled prevents other bones/joints from moving.
Make Your Mesh
Select the body image and click on the Mesh toggle in the Selection Panel. Click on the Edit Mesh button and use the Draw Mesh tool to create the contour of your mesh. Try to space the vertices evenly around the tail. Also, try to have the same amount of vertices on both sides of the tail.
Connect Bones to the Mesh
Next up we need to connect some bones to our mesh. Click on the plus icon next to Connected Bones. Select the bones we created earlier and press Done. Note that you can also double click on the bone names here to rename them.
Now that the bones are connected to the mesh, we need to tell them how they should affect each vertex. This is done in the Edit Weights mode by painting on your mesh. Select a bone as your brush, and paint on the vertices. Tweak your brush properties to add/subtract the influence of each bone on your vertices.
Note that you can also switch your map to only show the selected bone. The Intensity value below this affects only the map preview on your screen. Crank this value up to make sure only the vertices you want are being affected.
Now exit the Edit Weights mode and try rotating your bones to test how your weights are working. You may need to jump back into the Edit Weights mode to make a few tweaks before getting a smooth end result. Take a look at what our final weights look like in the image above.
When you’re happy with how your mesh is behaving, switch to Animate mode and keyframe your bones to test out some animations. If you want to see how we setup the tail movement in our animation, you can grab the file here. Drag and drop it into an empty new file in Nima.
We’ll soon be adding a new mode that will allow you to control the exact numerical values of weights on each vertex. We realize weights can be a bit tricky, and this mode will help both by giving you more control and by showing what’s going on under the hood. As you can see in the image above, we have one vertex selected. On the left, you can see that each bone has a weight (or influence value) on this vertex. A value of 1 means that a bone is fully controlling that vertex. A value of 0 means that the bone’s transformations will have no effect on that vertex.
You’ll notice that we also have a Pose dropdown in this updated Edit Weights mode. This will allow you to test poses directly in the Edit Weights mode without having to close the view.
Originally published at 2Dimensions.com on February 28, 2017.