GMH 2 GMH Poly Style Tutorial

Transcription

1 GMH 2 GMH Poly Style Tutorial 1 CONTENT 2 Prepare polygon hair models Create GMH Poly Style System Convert polygon meshes to GMH Surface Edit GMH Poly Style System EDIT TUBE ROTATION EDIT SURFACE HAIR THICKNESS ( HAIR CLUMP PER EDGE LOOP ) Edit GMH Surface override Optimization Best practice & Optimization Other settings... 9 Page 1

2 2 Prepare polygon hair models GMH2 is a script to convert polygon base meshes to hair so you would need to create polygon hair models before using GMH2. Open file GMH2.6_tutorialFile001_basePolygonHairModel.ma You will see a pre-made model with polygon hair style, this is an example of how the hair model could be setup to work with GMH2. It does not need to be super detail, draft block-out meshes are good enough for guiding GMH hair tubes. The mesh model are already separated into two groups "HairTop" and "HairBottom" so we can easily select them part by part to convert. Hair bottom group that goes around hair area 's border Hair Top group that fill inside hair area Tip : There are many ways to create base polygon hair models: You can quickly block out hair meshes using NURBS curves in Maya and convert NURBS surface to Polygon. See "Nurbs" and "Curves" group in the example file : GMH2.6_tutorialFile001_ basepolygonhairmodel. ma Using ZBrush 's Tube Brush or Fiber Mesh with flat Tubes settings. For detail workflow please visit this link to tutorial "ZBrush Maya Game Hair" by Daniel Cahill Page 2

3 3 Create GMH Poly Style System Next step is to create a GMH Poly Style System to convert polygon meshes to GMH Surfaces. Click on " Create GMH Style" and enter "RedHair" ( Or any name you like ) as name of the new GMH Poly Style System ( check "polygon Style System" check box to create GMH Poly style System"). Click on "RedHair_GMHPolyStyleSystem" on GMH2 window to set it as current GMH Style System. 4 Convert polygon meshes to GMH Surface Select one of the hair base mesh and click "Apply GMH Style" to convert it to GMH Surfaces, GMH will generate Maya hair mesh tubes growing along the base surface. Go through the rest of the hair base meshes to convert all hair meshes to GMH Surfaces. There might be some surfaces converted in wrong direction, you have to click on "rotate" button to rotate the direction of the hair tubes. By default, GMH2.6 will create a shader with color ramp applied to GMH Poly Style system so user can see the direction of the poly hair tubes easier. Make sure you have Texture view turende on in Maya Viewport. Multiple surfaces can be selected and rotate/convert at the same time. Page 3

4 Move the HairTop group aside so we can select and convert the HairBottom group easily. Select all hair base Mesh in the HairBottom group. Click "Apply GMHStyle" to convert all selected meshes to GMH Surfaces. Select surfaces that are currently in wrong direction, and click "rotate" until they are in correct direction. -Note: You can use the "Reverse" button to quickly reverse the hair direction 180*. Note: -You can carry on poly editing on those converted GMH Surface such as: Extrude, Insert Edge Loops, Bevel ( except combine and extract/separate), Assigning deformers like latice-ffd, wave, squash etc as long as the grid topology is maintained. -GMH Surface 's hair tubes will automatically follow and take shape of the new meshes shape. -Delete histories of converted surface are also safe. Important: -The mesh name has to be unique in the scene otherwise GMH will not recognize the surface. Make sure you have clean up the scene and rename/delete histories of all the base mesh properly. -Make sure the timeline are at frame 1 or 0 otherwise GMH Surface 's hair will not update to follow the base surface. Page 4

5 5 Edit GMH Poly Style System When we have converted all meshes to GMH Surface and rotate them in right direction, the next step is to tweak GMH Poly Style System and individual GMH Surface settings. Open up the next file in tutorial_files folder : GMH2.6_tutorialFile002_convertToGMHSurface.ma You will see a hair models fully converted to GMH Surface. 5.1 EDIT TUBE ROTATION Looking closely at the hair tubes generated on GMH Surface, you will notice that some GMH Surfaces have hair tubes facing outward that cover the base meshes 's surfaces nicely. GMH2 default settings for tubes orientation are setup to be good for most cases however some GMH Surfaces are still having hair tubes oriented in wrong direction. You can fix this by selected the GMH Surface with wrong oriented hair tubes and change the Tube Rotation slider under Surface Edit tab until you feel the result are good enough. Go through every GMH Surface to see if there is any GMH surface you might want to change the tube rotation. Page 5

6 5.2 EDIT SURFACE HAIR THICKNESS ( HAIR CLUMP PER EDGE LOOP ) Rotate camera to back of the hair mode, the main GMH Surface that make up most of back head area has very loose density of hair clump. Because GMH generate hair clump base on number of edge loop of the original mesh surfaces. The attribute " Hair Tube Num" in PFXBrush section control the number of hair clump per edge loop will be generated. By default it's 1 mean there will be 1 clumps will be generated for each edge loops of the original meshes. However it is not good for all GMH Surface sharing the same density of hair clump per edge loop, you might want to assign different hair clump density to some surface ( For example: denser hair clump for bigger surfaces at the back of the hair model and looser hair clump for smaller surfaces around forehead.) Select the surface you want to make it thicker and Edit the "Hair Tube Per Loop Multiply" slider under "Surface Edit" tab to override/increase the hair Tubes per edge loop of selected GMH Surfaces Note: GMH Poly style system 's Hair Tubes per Loop is the same as GMH Hair style system, the only different that it can be controlled interactively by "Hair Tube Per Loop Multiply" slider. The two buttons " Thicken" and "Thinning" are also work fine for Poly Style GMH Surfaces. Page 6

7 5.3 Edit GMH Surface override You can select one GMH Surface and edit its override style setting by adjusting GMH Attributes under Extra Attributes tab in Attributes Editor of each GMH Surface. For example you can override the front hair surface to have more hair tube and smaller tubes. Note: Not all attributes are working for Poly Style GMH surface because some of these attributes are for GMH Hair Style System. 5.4 Optimization Moving on to Optimization, Hair tubes modeling are very heavy on tris-count thus this workflow is only recommended for next-gen game with high requirement for hair. Open file : GMH2.6_tutorialFile003_tweak.ma for hair model file with final edited GMH Poly Style System and GMH Surfaces. Let check the tris-count for current hair model. Go to Display -> Heads Up Display -> Poly Count to bring up Maya 's poly count GUI on viewport. Select the RedHair Poly Style System in GMH window or Outliner. You will see the polycount for the current selected poly style system. Page 7

8 Right now it is at 12,698 tris- which is fairly acceptable for next-gen quality. But you do have options to raise this up for better quality or lower tris-count for lower spec or creating LOD by following methods : 1 - Reducing Hair tube num while increase Hair tube Width Mul of overall GMH Poly Style System or override settings of GMH Surfaces. 2 - Reducing Hair segment mul - strip down hair tube 's segments of minor GMH Surfaces. By doing above optimizations ( For both GMH Style System or override surface settings ), we can reduce the tris-count to 7900 tris without sacrifice too much quality of the final hair model. See file : " GMH2.6_tutorialFile004_optimization.ma" for example. Or if we want to increase quality and tris-count, we can increase the hair tube num value in GMH Poly System while reducing hair tube width this will add much more definition and detail to the hair model. See file:" GMH2.6_tutorialFile004_optimization_HI.ma" for example. Using Hair Tube Num and Tube Width values in GMH Poly Style System attributes can control the overall quality of hair mode. 5.5 Best practice & Optimization Now you have finished converting and tweaking your hair model. Time to wrap it up and move on to Baking & Texturing. There are some notes to remember while converting: -Put original hair meshes together under separated group for easier selection and converting. -Assign unique name to each hair meshes to avoid GMH2 bug while converting. -Delete Histories are safe for original Hair meshes. -Do not delete histories of GMH Style System node otherwise all connection and expression inside GMH Style System Node will be broken. -The base mesh name has to be unique in the scene otherwise GMH will not recognize the surface. Make sure you have clean up the scene and rename/delete histories of all the base mesh properly. -Make sure the timeline are at frame 1 or 0 otherwise GMH Surface 's hair will not update to follow the base surface. Page 8

9 5.6 Other settings There are many other attributes to work with hair styling inside GMH Poly Style System Node, this tutorial will only cover some of the most important settings that are essential to style the hair. If you want to know more about these settings please take a look at Autodesk Maya Hair System Node: Autodesk PFX Brush : Paint-Windows-and-Editors-Paint-Effects-Brush-Settings-htm.html Page 9