Hey everyone, in this tutorial we’re going to take a look at how you can create and customize collision shapes and weight maps for humanoid characters to achieve the best soft-cloth physics results. We’re going to demonstrate 2 different ways to paint weight maps which allow us to manipulate the soft cloth behavior. Let’s start off with the basics by creating collision shapes, using this humanoid character to demonstrate. You can see there are a lot of accessories here. In general, clothing like pants will be bound to the character’s body mesh at varying skin weight levels, so it’s really only looser items like capes, dresses or skirts that interact with collision shapes. In this case, we need to add the cloth effect to both Cloth01 and Cloth02, which are the 2 parts of the character’s cloak. We’ll need to start of by creating a collision volume for our character, so let’s hide all the accessories to simplify the scene, then select the character and enter into the Character Collision Shape Editor. I’ll check Collision On and Show Active Shapes, of which there are none yet. I’ll start with the chest by selecting it and then clicking the Activate Selected Part checkbox. You’ll need to use the transform, rotate, and scale gizmos to adjust the size and position of the collision shape to cover the upper body of your character. The collision mesh should align with the character mesh as closely as possible. The process is the same for the other collision shapes. Create them and align them with their respective body parts. Keep in mind that more collision shapes require more resources to calculate, so it’s good practice to only create collision shapes for those body parts which will interact with the cloak. In this case, we don’t need them for the head, shoes, or lower legs for example. OK now that that’s done, let’s look at painting a weight map using Blender. I’ll start by selecting the Cloth01 mesh and exporting the selected item to OBJ from the File menu. I’ll then proceed to import it into Blender and go into Texture Paint mode, then create a new Base Color texture and renaming it. We don’t need alpha data in this case so we can deselect that, and change the base color to black. I’ll change the display to the weight map we just created, and you’ll see the UV outline appear. What I need to do next is paint the area that I want to have a soft cloth effect white. Any part that needs to be fixed to the character like the collar in this case needs to remain black. It’s also a good idea to use the Soften tool to create a softer gradient between black and white to create a smoother and more gradual effect. Once you’re done, just go to Image and Save As to export the texture. Back in Character Creator, I’ll make sure the same Cloth01 mesh is selected, and then activate physics from the Physics tab. I’ll then proceed to load in the weight map that we just created. After it’s loaded up, I can then double click on General to load some physics preset values, and then a test motion. Be sure that you have both rigid and soft cloth simulation enabled in the toolbar to see the simulation. OK next let’s see how we can paint a weight map using a 2D tool like Photoshop. We’ll do this for the Cloth02 mesh. Once it’s selected, I can go over to the Material tab and find the Base Color texture. To export it, you can either save and import manually, or else simply use the Launch button which will launch the Base Color map, and then launch the UV map as well. In Photoshop, you’ll end up with both the Base Color and UV maps. The next step is to right-click on the UV Reference layer and duplicate it to the Base Color project. This allows us to align it with the base color pattern texture so we can see where we need to paint our weight map. You can confirm this by comparing the pattern at the base of the neck in Character Creator, and the position of that same pattern in Photoshop. In this case, the black area should be on the right side of our wireframe as that coincides with where the mesh connects with the character’s neck. To start painting, let’s select the UV Reference layer and use the Object selection tool to select the area that we want to paint, which is the wireframe for the cape. I’ll then proceed to use the Brush tool to create a monochromatic gradient similar to what we did earlier in Blender. Again, it’s important that the connection point to the character is a solid black, with a soft gradient to the part of the mesh that you want to be influenced by soft-cloth physics. After we’re done, we can save it out from Photoshop as WeightMap02.PNG, and then proceed to go into iClone and load it up the same way. I’ll then playback to see the results. You’ll notice right away that they are not ideal, as both of our soft cloth layers are breaking through each other. To resolve this, you can go into Project Settings and activate Soft vs. Soft Collision. A higher Margin value here will make it less likely that there will be any mesh breakage, but also means that there will be more space between the two layers by default. It’s ideal to test out your results via trial and error to find the best results for your scenario. After that, you can playback again to simulate. Is looking good. That’s how you can easily activate collision shapes and turn any accessory into a soft cloth simulation. Thanks for watching everyone, and I’ll see you in the next video.
