{"id":389,"date":"2014-09-16T17:05:46","date_gmt":"2014-09-16T17:05:46","guid":{"rendered":"http:\/\/fusion360.wpengine.com\/adding-creases-to-your-forms-deep-dive\/"},"modified":"2016-03-17T18:24:33","modified_gmt":"2016-03-17T18:24:33","slug":"adding-creases-to-your-forms-deep-dive","status":"publish","type":"post","link":"https:\/\/www.autodesk.com\/products\/fusion-360\/blog\/adding-creases-to-your-forms-deep-dive\/","title":{"rendered":"Adding Creases To Your Forms – Deep Dive"},"content":{"rendered":"

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The September update featured a brand new underlying technology for adding creases to T-Splines models. Although this just sounds like an enhancement to an existing modelling feature, the changes we made were far more significant than that: this was the result of a development effort spanning many months to try to remove some of the biggest confusions and pain points for new (and experienced!) users of the Sculpt workspace, which extend beyond just the Crease tool. This post goes into some detail about what exactly these changes are, the problems we tried to solve, and some ideas of what these changes will hopefully allow you to now accomplish.<\/span><\/p>\n

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Converting old models<\/strong><\/span><\/p>\n

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Probably the first thing to mention is that these changes required us to update the way T-Splines work, and your existing Sculpt models will need to be upgraded to take advantage of the changes. The next time you make edits to any Sculpt models created prior to the September update, you\u2019ll see this dialog box pop up:<\/span><\/p>\n

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\"UpgradeDialog.png\"<\/span><\/p>\n

We strongly recommend pressing OK here; after a few seconds the model will be upgraded to the new version. The reason we don\u2019t just do this upgrade automatically is that there is a possibility that models may change shape in regions around existing creases, or where surface boundaries have sharp internal corners; and of course we wouldn\u2019t want any risk of changing your models behind your back! But in many cases, this upgrade won\u2019t affect your shape at all. You can Undo if the upgrade made an undesirable shape change.<\/span><\/p>\n

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Creases and Star points<\/strong><\/span><\/p>\n

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For those who may not have\u00a0used it before, the Crease tool is available in the Modify menu in the Sculpt workspace, and is designed to add sharp edges\u00a0to your otherwise smooth Form\u00a0bodies:<\/span><\/p>\n

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\"CreaseInMenu.png\"<\/span><\/p>\n

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Probably the most common problem people would encounter when using the Crease tool in previous versions was that other edges on the model would become unexpectedly creased as well. Something like this:<\/span><\/p>\n

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\"CreaseBoxOld.png\"<\/span><\/p>\n

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In most cases, this was caused by the \u2018unhappy relationship\u2019 between creases and star points (for more information on what star points are, check out this video<\/a><\/strong>). In previous versions of Fusion 360, a crease which encountered a star point would fire-out creases from that star point in all directions (technically, star points could only either be ‘all smooth’ or ‘all creased’). For models with multiple star points close together – like a box primitive – the creases that got fired out would then likely encounter other star points on the model, eventually resulting in many star points becoming creased.<\/span><\/p>\n

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With the new creasing method, creases can enter a star point without creasing any other edges. This means that a crease can end at a star point, like this:<\/span><\/p>\n

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\"CreaseBoxIntoSP.png\"<\/span><\/p>\n

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or travel right through a star point, like this:<\/span><\/p>\n

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\"CreaseBoxAroundSP.png\"<\/span><\/p>\n

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A nice simple example of how this can be used: create a primitive box and crease one or more entire loops of edges (this might be easier by selecting faces as inputs for the crease: see the tip lower down). You should end up with one or more rounded-rectangular faces. By playing with the dimensions of the box (either before or after creasing), it\u2019ll be pretty easy to achieve\u00a0some recognizable consumer product\u00a0forms\u2026<\/span><\/p>\n

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\"BoxTablet.png\"<\/span><\/p>\n

\"BoxMP3.png\"<\/span><\/p>\n

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Crease Fade-outs and Yellow Regions<\/strong><\/span><\/p>\n

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With our previous creasing method, creases would always have an additional \u201cfade-out” area, travelling 2 edges beyond the selected edges:<\/span><\/p>\n

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\"GuitarOldStyleCrease.png\"<\/span><\/p>\n

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The new creasing method works a little differently: creases will now start and stop immediately at the ends of the edges you select<\/strong>.<\/span><\/p>\n

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\"CameraNewCrease.png\"<\/span><\/p>\n

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When testing this internally, we felt that the two-edge fade-out from the old crease method actually gives your creases a nice smooth visual quality. With the new creases stopping immediately, it’s more difficult to achieve smooth transitions like this. So in cases where it’s technically possible to give your crease a smooth fade-out, we\u2019ll still do that<\/strong>.\u00a0<\/span><\/p>\n

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This all relates to the yellow regions you now see when you open the Crease command:<\/span><\/p>\n

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\"IronYellow.png\"<\/span><\/p>\n

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These yellow regions indicate areas where we can’t <\/em>give you a two-edge smooth fade-out<\/strong>. If an end of a crease lies within a yellow region, this crease end will terminate directly where the edge selection finishes.<\/span><\/p>\n

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\"IronNewCrease.png\"<\/span><\/p>\n

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If any of your crease ends lie outside of the yellow regions, we will automatically give you a smooth two-edge fade-out here\u00a0(even if the fade-outs themselves enter a yellow region):<\/span><\/p>\n

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\"IronFadeCrease.png\"<\/span><\/p>\n

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The areas covered by the yellow regions are determined by the positions of particular special points on the model. To be specific, you will get yellow regions within a two-face radius of any of the following points on your model (these points are highlighted\u00a0as yellow dots when\u00a0the Crease command is active):<\/span><\/p>\n