This lesson will cover the use of geometry mode to transform a brush’s shape, or create an entirely new brush. There are several different ways a brush can be manipulated in \u201cgeometry mode\u201d . Select your builder brush and then hit the geometry mode button (diagram 1<\/strong>).<\/p>\n Diagram 1: Geometry Mode Button<\/p><\/div>\n Diagram 2: Polygon Components<\/p><\/div>\n If you are in geometry mode all corners of your builder brush will have turned into large red squares. When manipulating your brush you should keep the different components of a brush in mind (diagram 2<\/strong>). Using these components often and effectively will save you time. Lets change the position of our \u201cBuilder Brush\u201d components using the transform tools. Start by making sure the geometry mode has been turned on.<\/p>\n Diagram 3: Geometry Tool Options<\/p><\/div>\n Edit<\/strong> Extrude<\/strong> <\/p>\n Don’t forget you can also affect the translate handles without pulling on them. Try using these commands:<\/p>\n <\/p>\n Diagram 4: BSP Extrude Example<\/p><\/div>\n Brush Clip<\/strong> Diagram 5: BSP Clipping Example<\/p><\/div>\n The normal direction is changeable in the \u201cProperties\u201d section. Reversing the normal will reverse the cut. The normal has to be flipped before the cut is made to have any affect on the brush. Underneath \u201cFlip Normal?\u201d is the option \u201cSplit?\u201d. This option will take the part of the brush that is usually clipped off and create a separate brush out of it .<\/p>\n Pen<\/strong> Try connecting a punch of points together in a random shape. You will notice that the shape extrudes in the coordinate that matches its view. For an example of this create a shape in the top orthographic view and notice that it has been extruded along the Z axis. This extrusion will follow the world coordinate associated with the orthographic view you created it in.<\/p>\n In the \u201cSettings\u201d section you will notice several different options available to you. If \u201cAuto extrude?\u201d is turned off you will not get a default coordinate extrusion when you complete your pen path. The \u201cCreate Brush Shape?\u201d option is used in conjunction with several features including the \u201cLathe\u201d tool. When creating a shape you will notice that the editor always triangulates your shape. If this is something that you don’t want you can tick off the \u201cCreate Convex Polygons?\u201d option and your new shapes will consist of quads and n-gons (diagram 6<\/strong>). Our last option is \u201cExtrude Depth\u201d. This is the default extrusion depth your pen tool will create when completed.<\/p>\n Diagram 6: BSP Clipping Example<\/p><\/div>\n Lathe<\/strong> The last two options will help to control how much of a 360% sweep your shape will occupy. The \u201cTotal Segments\u201d option will set how many segments will make up the whole 360% turn. The \u201cSegments\u201d section will determine how many of those segments to actually produce.<\/p>\n Let’s make a simple square with the \u201cPen\u201d tool and the \u201cAuto Extrude?\u201d option turned off. Start in the top orthographic view and make your four point selection (diagram 7<\/strong>). Now highlight the Y coordinate view (top right by default) and re-select your pen shape. In your options box set your \u201cTotal Segments\u201d option to 16 and your \u201cSegments\u201d to 8. Now go ahead and lathe your selected shape.<\/p>\n You will notice that the inner radius of the lathe makes a semi circle. This is because our \u201cSegments\u201d option was set to half of our \u201cTotal Segments\u201d.<\/p>\n Diagram 7: BSP Lathe Example<\/p><\/div>\n <\/p>\n Delete<\/strong> Create<\/strong> Diagram 8: BSP Create Face<\/p><\/div>\n Flip<\/strong> Triangulate<\/strong> Diagram 9: BSP Triangulation<\/p><\/div>\n Turn<\/strong> Diagram 10: BSP Turn Edge<\/p><\/div>\n Split<\/strong>![\"Unreal](\"https:\/\/terrymatthes.com\/2024\/wp-content\/uploads\/2011\/07\/BSP01_02.png\" "\\"\\"")
<\/a><\/a>Tools<\/h3>\n
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\nWhile in edit mode you can select and manipulate single or grouped vertices, edges and faces. Try selecting one of the vertices and then hold down CTRL and select a few more. There are no options in the \u201cProperties\u201d section (diagram 3<\/strong>) of the Geometry Tool for edit mode.<\/p>\n
\nThis mode is available exclusively for manipulating the faces of your geometry. To access this mode you will first have to select a face that belongs to your brush. Only after doing this will the radio button become available.<\/p>\n
\n<\/a>To extrude a face simply select the face you want to extrude and pull outwards on the coordinate handles. For a more precise extrusion you can enter the \u201cLength\u201d and \u201cSegments\u201d of your desired extrusion into the \u201cProperties\u201d section. A properly extruded face can be seen in diagram 4<\/strong>.<\/p>\n\n
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\nHave you ever wanted to split a brush in two, or perhaps make two brushes from a single brush. If so the \u201cBrush Clip\u201d tool is just what you need. In the orthographic view port hold down the CTRL key and click with the RMB. You need two points that clearly cut across your brush to make the clip work (diagram5<\/strong>). Click \u201cApply\u201d and you will notice that your brush has been split. You should also notice a line perpendicular to your clip line. This line is the \u201cnormal\u201d.<\/p>\n<\/a>
\nThe pen tool can create new brushes from points you lay down in a orthographic view. To create a brush connect three or more points ending at the first while holding down CTRL and clicking the RMB. The shape is set to auto extrude to a depth of 256.<\/p>\n<\/a>
\nThe \u201cLathe\u201d tool tries to take your shape and revolve it 360% around the dominant coordinate of your current orthographic window. The \u201cLathe\u201d option can only be selected if you create a polygon with the \u201cPen\u201d tool while the option \u201cCreate Brush Shape?\u201d is turned on. Your shape will be green in colour.<\/p>\n<\/a>Modifiers<\/h3>\n
\nFaces and verticies may be deleted using the \u201cDelete\u201d tool. Be careful when deleting. Look at your geometry closely and make sure you won’t get any unwanted shape changes from the deletion. Any faces you delete can always be repaired by using the \u201cCreate\u201d modifier.<\/p>\n
\nGreat for filling holes or bridging BSP the \u201cCreate\u201d modifier works using verticies. Add a simple cube brush to the world and delete one of it’s faces.Now select the four verticies around the open face in a clockwise fashion and then hit ENTER. The face will have been created with its normal direction facing outwards (diagram 8<\/strong>). If you were to make the same selection counter-clockwise the face will have been created pointing inwards.<\/p>\n<\/a>
\nThat thing we just talked about called the normal; it’s what the \u201cFlip\u201d modifier is all about. Working on faces, the Flip modifier reverses normals. Reversing a face’s normals flips the side of the polygon that is rendered. This is why you can’t see the insides of meshes when you pass through them in spectator mode. The normal for all of those faces is pointing outwards.<\/p>\n
\nFairly self explanatory, \u201cTriangulate\u201d breaks mesh faces up into triangles (diagram 9<\/strong>). If you notice a surface of your BSP is rendering funny triangulate the faces giving your the trouble. Chances are they’re n-gons of some sort. Try creating a cube brush and selecting it’s top face. Now triangulate that face and notice how that quad (four edged polygon) was broken up into two tris (three edged polygon).<\/p>\n<\/a>
\nIf you have two triangles on a brush that share a common edge you can \u201cTurn\u201d that edge .This rotates the the common edge of the triangles. Doing this causes the line that connects the two triangles to snap the the other 2 verticies that make up their 4 verticie border (diagram 10<\/strong>). If you still are unclear on this try using the pen tool to make a non extruded shape. Now \u201cTriangulate\u201d this shape and practice turning some border edges of triangles around.<\/p>\n<\/a>
\nThe \u201cSplit\u201d tool adds \u201cedge loops\u201d or a series of verticies that run around your mesh connected by edges. Create a cube and select one of its edges and then use the Split modifier. Notice that a line was run around your shape that is perpendicular to the original edge you selected (diagram 11<\/strong>). This will always be the case when Splitting. In conjunction with the \u201cExtrude\u201d tool, splitting can work well to help you achieve whatever BSP shape you need. Diagram 13 illustrates the idea behind this.<\/p>\n