maya cloth tutorial - important please read
I just viewed the maya cloth free tutorial, I'm not sure how different the other cloth tutorial is or how old the video is but I have a few things to point out and I guess correct and critique from the video...
this is in no way meant to be deamoning this is information that most cloth artists need to know if they don't know...
ok, now... on to the notes I took...these are the areas I will be touching up on in this post....and possibly a little more beyond
Creating panels for cloth
Cloth Collision objects and settings
Resolution of cloth
Creating Panels for cloth...
this is one of the two areas I see people asking me about, creating your panels is like sewing, if they're not created right you will have unnatural folding, pinching, and other irregularities when you go to animate. I recommend going to wal-mart or a clothing store and buy a cloth pattern or two for shirt and pants. The small white sheet that comes with the actual patterns has all of the information you need to create the panels correctly and how and where to sew them together. Do note that there are going to always be one or two things you have to modify to make it work, but as long as you stick close to the pattern your cloth will be fine. Also the panel size makes a difference with the cpSolver, if they get to be too small the solver will have problems solving, and you don't want that...
In the tutorial the instructor has seams going across the shirt over the breast. Why? Having this may cause an unnatural animation in the cloth. You already have a separate curve on the sides to connect the front and back you don't actually need the previously mentioned curves.
Cloth Collision objects and settings
When you create a collision object, you have 3 attributes to worry about but only 2 of them you really need to worry about unless you have multiple collision objects.
Collision Offset - This is how far the cloth object sits off of the character. The lower the number, the better. This will tie into the resolution of the cloth which I will go over later in this post. Do not use 0, it will cause problems with the solver.
Collision Depth - This is how far the cloth is able to penetrate the collision object before it is pushed back out. This number should be lower than your Collision Offset. The smaller this number is, the better. Do not use 0, it will cause problems with the solver.
Collision Priority - This is used for multiple collision objects. The lower number will always have priority of which the cloth will solve for first. Lets say you have a character leaning up against a wall. You have two objects both made as collidable, But the cloth is sort of ignoring the wall and not the character. This is where Collision Priority comes in handy. Set the wall to 1 and the character to 2. What happens here is the cloth will solve for the wall first then solve for the character.
This is the setting that I see a lot of people get wrong all of the time. This is located in the cpSolver node that gets created when you make cloth. What this will do, when you set it right, is make your character a real world size. There is an actual equation that goes into this, Solver Scale = Real World Size in cm / Maya Units which is also in cm...This is set up in your preferences, the equation is still the same throughout.
Let me go into more detail
Say you want your character to be 5'6, and in maya your character is 10 centimeters tall because maya units according to your preferences is set up in centimeters then 167.6 / 10 = 16.76 in your solver scale.... Now the size of your character is important, you want to keep him/her/it a reasonable size. I recommend making the size of the character in maya units as 1cm = 1ft. Doing this will have your solver scale set to 30.5 as that is what the conversion will be for 1 ft to 1 cm... (www.worldwidemetric.com has a calculation tool to help you convert your numbers. It does not convert to cm so you will have to take mm and divide it by 10..) 5'6 is 1676.40mm which in turn is 167.6cm) so if your character is 5.5 maya units high (5'6") - (5/10 = .5 like 6/12 = .5) then 167.6 / 5.5 = 30.47272727... round that off to 30.5 that is your solver scale....
Now, the most important part of the Solver Scale attribute - DO NOT CHANGE AT ALL... how your cloth settles and acts is dependant upon how your panels are cut and sewn as well as your cloth properties all of which are under your cloth menu set.... sure setting the solver scale higher will make it drape a lot more loose, but it will only work for so long before the solver starts having trouble solving....
I know the math in that is confusing, how I came up with 5.5 well I just took the excess inches out of that 1 foot and divided it by 12 which gives me a percentage, round that percentage off to 2 decimal places and there you go... its still confusing so I'll stop there...
Resolution of cloth
Here's another biggie, not as important as the solver scale, but important enough to make a difference with collision detection. Panel shape and size is important with this... Use the Resolution Factor in your panels with the Base Resolution, the higher the number the tougher it will be for the solver to solve. 25 * 25 is 2500 it will solve much better than having the Base Resolution to 2500 and, in using those 2 numbers sparingly, while it won't give your cloth enough geometry for collision, its a good start to start from and your solver won't crap out on you. My cloth simulations are around 35*35 any higher and the solver will give me problems.... you absolutely need a lot of resolution for collision detection, it is important in how your cloth animates and reacts to the character and scene around you.
Ok, the final thing here before I go. Run a local simulation before you run anything else with cloth. Running a local simulation will allow you to view how your cloth drapes and you will not have to worry about deleting your cache(cash). One thing I do need to point out, open your cpSolver attribute there is a setting called Adaptation Control..you want to set this to No Effect. What happens is, if something is wrong with your cloth and the solver starts giving you warnings and has trouble it will start the timer and create a cache file on top of that, and you will have a lot of problems from there and have to delete the cache file. This way, you can avoid that and not have to deal with the time, time slider or cache file til you're ready to run the actual animation. Always use your local simulation first. Then you can set the other solver attributes mentioned in the video for run up and animation. Just make sure everything else is done properly and you will be fine