# Rebuild CurveΒΆ

This example shows how to create a command which can read curve attributes. It is made up of the command itself, as well as a visitor object which we use to scan a mesh layer for curve polygons.

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234``` ```import lx import lxu.select import lxu.command import lxifc from math import floor def dSqr(vec1, vec2): '''Quick function to get the distance squared between two points''' dist = 0.0 for i in range(3): dist += (vec2[i] - vec1[i])**2 return dist class CurveFinder(lxifc.Visitor): '''This visitor object will scan through selected polygons and create a dictionary of those polygons who are curves. The ID of the polygon will be the key, and the value will be the position or its root vertex. Later, we'll compare this position to the position of curve objects we get to make sure we're only affecting the curves the user intends.''' def __init__(self, polyAccessor, pointAccessor): self.poly = polyAccessor self.point = pointAccessor self.curves = {} def vis_Evaluate(self): if self.poly.Type() == lx.symbol.iPTYP_CURVE: p = self.poly.VertexByIndex(0) self.point.Select(p) pos = self.point.Pos() ID = self.poly.ID() self.curves[ID] = pos class CurvePoints(lxu.command.BasicCommand): def __init__(self): '''After initializing the command, arguments are added one by one. These arguments can then be referenced later by the order they were added, so the first argument will be index 0, the second index 1, etc.''' lxu.command.BasicCommand.__init__(self) self.dyna_Add('mode', lx.symbol.sTYPE_BOOLEAN) self.dyna_Add('remove', lx.symbol.sTYPE_BOOLEAN) self.dyna_Add('count', lx.symbol.sTYPE_INTEGER) self.basic_SetFlags(2, lx.symbol.fCMDARG_OPTIONAL) self.dyna_Add('distance', lx.symbol.sTYPE_DISTANCE) self.basic_SetFlags(3, lx.symbol.fCMDARG_OPTIONAL) '''Adding a argument requires an internal string name for the argument, and a type for the argument. By default all arguments are required, but we can use the basic_SetFlags method to change that if we need to''' def fire(self, CMD): '''Call commands without lx.eval''' lx.service.Command().ExecuteArgString(-1, lx.symbol.iCTAG_NULL, CMD) def cmd_ArgUserName(self,index): '''This sets the user name for the argument of a given index. Ideally, these user names should exist in a message table inside of a config, but for this example it's not really all that important''' argNames = ['Use Spacing Distance', 'Remove Original Curve', 'Point Count', 'Point Spacing'] return argNames[index] def cmd_UserName(self): '''This sets the user name for the command itself. Again, we should ideally use a message table, but we will just use a string for simplicity''' return 'Rebuild Curve' def cmd_DialogInit(self): '''If the user doesn't provide all required arguments, modo opens a dialog to ask for them. When this happens, the cmd_DialogInit is called which allows us to set default values for our the command arguments''' self.attr_SetInt(0, 0) self.attr_SetInt(1, 1) self.attr_SetInt(2, 10) self.attr_SetFlt(3, .05) def cmd_ArgEnable(self,arg): '''When the command dialog opens and when the user interacts with it, modo calls this method for each of our arguments. That gives us a chance to read what the current values for arguments are, and choose if we need to disable an argument''' if self.attr_GetInt(0) and arg == 2: lx.throw(lx.symbol.e_CMD_DISABLED) elif not self.attr_GetInt(0) and arg == 3: lx.throw(lx.symbol.e_CMD_DISABLED) return lx.symbol.e_OK def cmd_Flags(self): '''cmd_Flags tells modo what kind of command we have. Since we're changing the state of the scene by altering geometry, we need to make this an undoable command''' return lx.symbol.fCMD_MODEL | lx.symbol.fCMD_UNDO def getCurve(self, layerScan): '''For organization, the command is split into two parts. This method grabs a curve object from the current mesh layer and returns it to the main execution method. If a curve is selected, we find which curve in the curve Group is the same as the selected one, and return it. Otherwise, we return all curves we find.''' # Layerscan lets us get the mesh as an item object, and as an editable mesh. curveItem = layerScan.MeshItem(0) self.mesh = layerScan.MeshEdit(0) self.poly = self.mesh.PolygonAccessor() self.points = self.mesh.PointAccessor() '''Getting a curve Group object from an item requires reading the crvGroup channel, casting the channel's value object as a value reference, and finally casting the object from the value reference as a curve group. The curve group is an item which contains all the curves within the provided item. We access an individual curve by using the ByIndex() method''' chanRead = self.scene.Channels(None,0) crvChan = curveItem.ChannelLookup('crvGroup') crvValObj = chanRead.ValueObj(curveItem, crvChan) valRef = lx.object.ValueReference(crvValObj) curveGroup = lx.object.CurveGroup(valRef.GetObject()) if curveGroup.Count()<1: return None '''We use our visitor to scan through any selected polygons and check if they are curves. If so, we make a dictionary with those curve IDs and the root vertex position.''' curveVis = CurveFinder(self.poly, self.points) selM = lx.service.Mesh().ModeCompose('select', None) self.poly.Enumerate(selM, curveVis, 0) '''For every curve that the visitor found, we want to pair it with a curve object from the curve group. We'll make a new dictionary, where the curve's ID is the key again, but the value will be the curve object itself.''' retCurves = {} for selCurve in curveVis.curves: dist = 9**99 '''There are no direct links to find which curve in the curve group belongs to a specific polygon in a mesh, so we need to compare the root position of the curve with the root vertices position. We assume the curve object with a root position closest to a given root vertex is the same curve.''' for i in range(curveGroup.Count()): curve = curveGroup.ByIndex(i) pos = curve.Position() tmpD = dSqr(curveVis.curves[selCurve], pos) if tmpD < dist: dist = tmpD idx = i retCurves[selCurve] = curveGroup.ByIndex(idx) return retCurves def basic_Execute(self, msg, flags): '''Even though the point count and spacing distance arguments are both optional, one of them has to be set. We check that first.''' if self.dyna_IsSet(2) or self.dyna_IsSet(3): mode = self.attr_GetInt(0) '''Next we need to make sure we didn't get a spacing distance of 0 or less, or a point count of less than 2''' if mode: dist = self.attr_GetFlt(3) if dist <= 0: self.e_BADDIST() return lx.symbol.e_ABORT else: ptCount = self.attr_GetInt(2) if ptCount <2: self.e_BADPTS() return lx.symbol.e_ABORT '''Finally, we can get a layerscan object in order to check if there are curves in the mesh.''' self.scene = lxu.select.SceneSelection().current() ls = lx.service.Layer() lscan = ls.ScanAllocate(lx.symbol.f_LAYERSCAN_EDIT | lx.symbol.f_LAYERSCAN_MARKPOLYS) curves = self.getCurve(lscan) if not curves: self.e_NOCURVE() lscan.Apply() return lx.symbol.e_ABORT '''All our tests passed, and we have at least 1 curve object to rebuild''' killSwitch = self.attr_GetInt(1) for ID in curves: curve = curves[ID] '''First we get a list of all the positions we want to form our curve from. Then we generate points there using a Point object''' if mode: ptCount = int(floor(curve.Length()/dist)) pts = [] for i in range(ptCount): curve.SetLenFraction(float(i)/(ptCount-1)) pts.append(curve.Position()) ptList = [] for i in pts: ptList.append(self.points.New(i)) '''We need to add the IDs from each newly created point into a storage object, and using that storage object we can create a polygon''' pBuf = lx.object.storage('p') pBuf.setSize(len(ptList)) pBuf.set(ptList) polyID = self.poly.New(lx.symbol.iPTYP_CURVE, pBuf, len(ptList), 0) '''Finally we check if the user wants to remove the original curve. If they do, we need to remove each of the verts, and then the polygon''' if killSwitch: self.poly.Select(ID) for i in range(self.poly.VertexCount()): self.points.Select(self.poly.VertexByIndex(i)) self.points.Remove() self.poly.Remove() self.mesh.SetMeshEdits(lx.symbol.f_MESHEDIT_GEOMETRY) lscan.Apply() '''These error dialogs catch known cases of failures earlier in the process''' def e_NOCURVE(self): self.fire('dialog.setup error') self.fire('dialog.title {Rebuild Curve}') self.fire('dialog.msg {No curve was found in the current mesh layer.}') self.fire('dialog.open') def e_BADDIST(self): self.fire('dialog.setup error') self.fire('dialog.title {Rebuild Curve}') self.fire('dialog.msg {Distance must be greater than 0}') self.fire('dialog.open') def e_BADPTS(self): self.fire('dialog.setup error') self.fire('dialog.title {Rebuild Curve}') self.fire('dialog.msg {A minimum of 2 points must be used}') self.fire('dialog.open') lx.bless(CurvePoints, "curve.rebuild") ```