前言
Qualoth是韓國FXGear公司推出的一款布料模擬插件，可以計算出很自然的衣褶以及動態效果，並且能應對大幅度動作的碰撞解算，可以和Houdini的Cloth Solver相媲美；
目前這款插件的教程很少，只能找到一個冗長的韓文視頻以及官方幫助文檔，沒有其他更詳細的教程；
我下載了for Maya的版本體驗了一段時間，摸索出大體的制作流程，現分享如下；
制作流程
Qualoth的制作流程和nCloth差別較大，主要是前期衣物建模流程的不同，前幾步類似傳統服裝制作：
1、先用Curve曲線根據真實的服裝板式圖“打樣“；
2、線條兩兩生成Pattern，依次把整件服裝的所有面片都生成好；
3、再把接縫處的曲線進行Seam縫合，；
4、開始局部模擬，使衣服適配人體模型；
5、接着設置緩存路徑和緩存名；
6、Play開始模擬就可以了~
在布料參數設置方面，可以先保持默認，但需要把Solver下的幾個參數重點設置一下：
重點參數
測試發現，以下幾個參數對解算效果的影響最大，請仔細參考數值范圍：
Frame Samples：
The number of sub steps to compute a frame. Using bigger numbers results in better accuracy in collision handling at the cost of increased computation time. 1~3 is reasonable for slow motions, 8~20 can be used for fast motions.
Frame 1 Frame 2 Frame 1.5 Frame 1 Frame 2 Frame 1.5 Simple Subsampling Exact Subsampling
Time Scale：
The time stretching factor. This value scales the time unit used in Maya. Suppose that one frame corresponds to 1/24 seconds in Maya, and if you set “Time Scale” to 10.0, one frame is interpreted as 1/240 seconds by the solver. You can create slow motion effect (bullet time effect) by controlling this value.
Length Scale：
The length scale makes the cloth objects under this solver look bigger or smaller than the actual size which is represented by the geometry. Note that each cloth object has “Length Scale” attribute and “Length Scale Map”. The final effective length scale of a cloth vertex is calculated as follows. Effective length scale = Cloth Length Scale X Cloth Length Scale Map X Solver Length Scale
MAX CG Iteration：
The maximum number of iterations for dynamics computation. To obtain the best results, do not let the solver hit this limit. You can verify the number of iterations used at each frame in the printed solver statistics (#CG)
CG Accuracy：
The accuracy index for dynamics iterations. As this value gets bigger, more accurate results are obtained at the cost of increased number of iterations. 4~6 are reasonable for not-stiff cloth, and use 7~9 for stiff cloth. Values greater than 9 are not recommended。
動力場
Qualoth也可以受Maya動力場的影響，具體操作如下：
1. Create a Maya field while selecting nothing. Do not select the cloth mesh at this time. See Fig. 12-1. 2. Select cloth vertices (not the mesh) to be affected by the field, and then select the field node. (The selection order is important). See Fig. 12-2. 3. Click “Qualoth>Connect Objects>Field>As Velocity”. 4. A field filter node is created and now you can edit the properties of the node. (Fig. 12-3)
經驗總結
如果模型組是用Maya的默認方式制作衣物模型，Qualoth解算出來的效果會比較僵硬，自然的衣褶效果也很難體現出來，所以最好讓模型組采用Qualoth的制作流程，使用Curve給衣服建立“打樣”線條，這樣才能獲得更自然的效果，這一點在Houdini的Cloth Solver中也一樣。