├── requirements.txt ├── README.md ├── LICENSE └── gds2obj.py /requirements.txt: -------------------------------------------------------------------------------- 1 | numpy 2 | gdspy 3 | triangle 4 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Python3 GDS to OBJ (Wavefront) files converter script 2 | 3 | This first version was built to create `.obj` 3D files from SDK130 PDK `.gds` files 4 | 5 | Lot of the work is based on the gdsiistl repo: https://github.com/dteal/gdsiistl 6 | 7 | Python libraries requirements: 8 | ``` 9 | numpy 10 | gdspy 11 | triangle 12 | ``` 13 | 14 | ## Usage: 15 | `python3 gds2obj.py file.gds` 16 | 17 | Outputs one file per layer named `file.gds_layername.obj` in the same folder as the original gds file 18 | 19 | 20 | ## Note from original gdsiistl script: 21 | 22 | Due to a limitation of the library used to triangulate the polygonal boundaries of the GDSII geometry, the polygon borders (i.e., all geometry) are shifted slightly (by a hardcoded delta of about 0.00001 units, or 0.01 nanometers in standard micron units) before export. Furthermore, due to another related limitation/bug (not yet completely understood; see source code comments), extra triangles are sometimes created covering holes in polygons. 23 | 24 | So the output mesh is not guaranteed to be watertight, perfectly dimensioned, or retain all polygon holes, but it should be arbitrarily close and err on the side of extra triangles, so a program (e.g., Blender) can edit the mesh by deleting faces and produce a negligibly-far-from perfect visualization. 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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It reads shapes from 12 | each layer of the GDSII file, converts them to polygon boundaries, then makes 13 | a triangle mesh for each GDSII layer by extruding the polygons to given sizes. 14 | 15 | All units, including the units of the exported file, are the GDSII file's 16 | user units (often microns). 17 | """ 18 | 19 | import sys # read command-line arguments 20 | import gdspy # open gds file 21 | import numpy as np # fast math on lots of points 22 | import triangle # triangulate polygons 23 | 24 | 25 | # get the input file name 26 | if len(sys.argv) < 2: # sys.argv[0] is the name of the program 27 | print("Error: need exactly one file as a command line argument.") 28 | sys.exit(0) 29 | gdsii_file_path = sys.argv[1] 30 | 31 | ########## CONFIGURATION (EDIT THIS PART) ##################################### 32 | 33 | # choose which GDSII layers to use 34 | 35 | layerstack = { 36 | (235,4): {'name':'substrate', 'zmin':-2, 'zmax':0, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 37 | (64,20): {'name':'nwell', 'zmin':-0.5, 'zmax':0.01, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 38 | # (65,44): {'name':'tap', 'zmin':0, 'zmax':0.1, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 39 | (65,20): {'name':'diff', 'zmin':-0.12, 'zmax':0.02, 'color':[ 0.9, 0.9, 0.9, 1.0]}, 40 | (66,20): {'name':'poly', 'zmin':0, 'zmax':0.18, 'color':[ 0.75, 0.35, 0.46, 1.0]}, 41 | (66,44): {'name':'licon', 'zmin':0, 'zmax':0.936, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 42 | (67,20): {'name':'li1', 'zmin':0.936, 'zmax':1.136, 'color':[ 1.0, 0.81, 0.55, 1.0]}, 43 | (67,44): {'name':'mcon', 'zmin':1.011, 'zmax':1.376, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 44 | (68,20): {'name':'met1', 'zmin':1.376, 'zmax':1.736, 'color':[ 0.16, 0.38, 0.83, 1.0]}, 45 | (68,44): {'name':'via', 'zmin':1.736,'zmax':2, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 46 | (69,20): {'name':'met2', 'zmin':2, 'zmax':2.36, 'color':[ 0.65, 0.75, 0.9, 1.0]}, 47 | (69,44): {'name':'via2', 'zmin':2.36, 'zmax':2.786, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 48 | (70,20): {'name':'met3', 'zmin':2.786, 'zmax':3.631, 'color':[ 0.2, 0.62, 0.86, 1.0]}, 49 | (70,44): {'name':'via3', 'zmin':3.631, 'zmax':4.0211, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 50 | (71,20): {'name':'met4', 'zmin':4.0211, 'zmax':4.8661, 'color':[ 0.15, 0.11, 0.38, 1.0]}, 51 | (71,44): {'name':'via4', 'zmin':4.8661, 'zmax':5.371, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 52 | (72,20): {'name':'met5', 'zmin':5.371, 'zmax':6.6311, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 53 | # (83,44): { 'zmin':0, 'zmax':0.1, 'name':'text'}, 54 | } 55 | 56 | # layerstack = { 57 | # (235,4): {'name':'substrate', 'zmin':-1, 'zmax':0, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 58 | # # (64,20): {'name':'nwell', 'zmin':0, 'zmax':0.1, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 59 | # # (65,44): {'name':'tap', 'zmin':0, 'zmax':0.1, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 60 | # (65,20): {'name':'diff', 'zmin':-0.12, 'zmax':0.01, 'color':[ 0.9, 0.9, 0.9, 1.0]}, 61 | # (66,20): {'name':'poly', 'zmin':0, 'zmax':0.18, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 62 | # (66,44): {'name':'licon', 'zmin':0, 'zmax':0.936, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 63 | # (67,20): {'name':'li1', 'zmin':0.936, 'zmax':1.136, 'color':[ 0.9, 0.9, 0.9, 1.0]}, 64 | # (67,44): {'name':'mcon', 'zmin':1.011, 'zmax':1.376, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 65 | # (68,20): {'name':'met1', 'zmin':1.376, 'zmax':1.736, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 66 | # (68,44): {'name':'via', 'zmin':1.736,'zmax':2, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 67 | # (69,20): {'name':'met2', 'zmin':2, 'zmax':2.36, 'color':[ 0.9, 0.9, 0.9, 1.0]}, 68 | # (69,44): {'name':'via2', 'zmin':2.36, 'zmax':2.786, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 69 | # (70,20): {'name':'met3', 'zmin':2.786, 'zmax':3.631, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 70 | # (70,44): {'name':'via3', 'zmin':3.631, 'zmax':4.0211, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 71 | # (71,20): {'name':'met4', 'zmin':4.0211, 'zmax':4.8661, 'color':[ 0.9, 0.9, 0.9, 1.0]}, 72 | # (71,44): {'name':'via4', 'zmin':4.8661, 'zmax':5.371, 'color':[ 0.2, 0.2, 0.2, 1.0]}, 73 | # (72,20): {'name':'met5', 'zmin':5.371, 'zmax':6.6311, 'color':[ 0.4, 0.4, 0.4, 1.0]}, 74 | # # (83,44): { 'zmin':0, 'zmax':0.1, 'name':'text'}, 75 | # } 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | ########## INPUT ############################################################## 84 | 85 | # First, the input file is read using the gdspy library, which interprets the 86 | # GDSII file and formats the data Python-style. 87 | # See https://gdspy.readthedocs.io/en/stable/index.html for documentation. 88 | # Second, the boundaries of each shape (polygon or path) are extracted for 89 | # further processing. 90 | 91 | print('Reading GDSII file {}...'.format(gdsii_file_path)) 92 | gdsii = gdspy.GdsLibrary() 93 | gdsii.read_gds(gdsii_file_path, units='import') 94 | 95 | 96 | 97 | print('Extracting polygons...') 98 | 99 | 100 | 101 | 102 | for cell in gdsii.top_level(): # loop through cells to read paths and polygons 103 | layers = {} # array to hold all geometry, sorted into layers 104 | 105 | print ("\nProcessing cell: ", cell.name) 106 | 107 | print("Flatenning") 108 | 109 | cell.flatten() 110 | 111 | # $$$CONTEXT_INFO$$$ is a separate, non-standard compliant cell added 112 | # optionally by KLayout to store extra information not needed here. 113 | # see https://www.klayout.de/forum/discussion/1026/very- 114 | # important-gds-exported-from-k-layout-not-working-on-cadence-at-foundry 115 | if cell.name == '$$$CONTEXT_INFO$$$': 116 | continue # skip this cell 117 | 118 | print ("\tpaths loop. total paths:" , len(cell.paths)) 119 | # loop through paths in cell 120 | for path in cell.paths: 121 | lnum = (path.layers[0],path.datatypes[0]) # GDSII layer number 122 | 123 | if not lnum in layerstack.keys(): 124 | continue 125 | 126 | layers[lnum] = [] if not lnum in layers else layers[lnum] 127 | # add paths (converted to polygons) that layer 128 | for poly in path.get_polygons(): 129 | layers[lnum].append((poly, None, False)) 130 | 131 | print ("\tpolygons loop. total polygons:" , len(cell.polygons)) 132 | # loop through polygons (and boxes) in cell 133 | for polygon in cell.polygons: 134 | lnum = (polygon.layers[0],polygon.datatypes[0]) # same as before... 135 | 136 | if not lnum in layerstack.keys(): 137 | continue 138 | 139 | layers[lnum] = [] if not lnum in layers else layers[lnum] 140 | for poly in polygon.polygons: 141 | layers[lnum].append((poly, None, False)) 142 | 143 | 144 | 145 | 146 | """ 147 | At this point, "layers" is a Python dictionary structured as follows: 148 | 149 | layers = { 150 | 0 : [ ([[x1, y1], [x2, y2], ...], None, False), ... ] 151 | 1 : [ ... ] 152 | 2 : [ ... ] 153 | ... 154 | } 155 | 156 | Each dictionary key is a GDSII layer number (0-255), and the value of the 157 | dictionary at that key (if it exists; keys were only created for layers with 158 | geometry) is a list of polygons in that GDSII layer. Each polygon is a 3-tuple 159 | whose first element is a list of points (2-element lists with x and y 160 | coordinates), second element is None (for the moment; this will be used later), 161 | and third element is False (whether the polygon is clockwise; will be updated). 162 | """ 163 | 164 | ########## TRIANGULATION ###################################################### 165 | 166 | # An STL file is a list of triangles, so the polygons need to be filled with 167 | # triangles. This is a surprisingly hard algorithmic problem, especially since 168 | # there are few limits on what shapes GDSII file polygons can be. So we use the 169 | # Python triangle library (documentation is at https://rufat.be/triangle/), 170 | # which is a Python interface to a fast and well-written C library also called 171 | # triangle (with documentation at https://www.cs.cmu.edu/~quake/triangle.html). 172 | 173 | print('\tTriangulating polygons...') 174 | 175 | 176 | num_triangles = {} # will store the number of triangles for each layer 177 | 178 | # loop through all layers 179 | for layer_number, polygons in layers.items(): 180 | 181 | # but skip layer if it won't be exported 182 | if not layer_number in layerstack.keys(): 183 | continue 184 | 185 | num_triangles[layer_number] = 0 186 | 187 | # loop through polygons in layer 188 | for index, (polygon, _, _) in enumerate(polygons): 189 | 190 | num_polygon_points = len(polygon) 191 | 192 | # determine whether polygon points are CW or CCW 193 | area = 0 194 | for i, v1 in enumerate(polygon): # loop through vertices 195 | v2 = polygon[(i+1) % num_polygon_points] 196 | area += (v2[0]-v1[0])*(v2[1]+v1[1]) # integrate area 197 | 198 | clockwise = area > 0 199 | 200 | # GDSII implements holes in polygons by making the polygon edge 201 | # wrap into the hole and back out along the same line. However, 202 | # this confuses the triangulation library, which fills the holes 203 | # with extra triangles. Avoid this by moving each edge back a 204 | # very small amount so that no two edges of the same polygon overlap. 205 | delta = 0.00001 # inset each vertex by this much (smaller has broken one file) 206 | points_i = polygon # get list of points 207 | points_j = np.roll(points_i, -1, axis=0) # shift by 1 208 | points_k = np.roll(points_i, 1, axis=0) # shift by -1 209 | # calculate normals for each edge of each vertex (in parallel, for speed) 210 | normal_ij = np.stack((points_j[:, 1]-points_i[:, 1], 211 | points_i[:, 0]-points_j[:, 0]), axis=1) 212 | normal_ik = np.stack((points_i[:, 1]-points_k[:, 1], 213 | points_k[:, 0]-points_i[:, 0]), axis=1) 214 | length_ij = np.linalg.norm(normal_ij, axis=1) 215 | length_ik = np.linalg.norm(normal_ik, axis=1) 216 | normal_ij /= np.stack((length_ij, length_ij), axis=1) 217 | normal_ik /= np.stack((length_ik, length_ik), axis=1) 218 | if clockwise: 219 | normal_ij = -1*normal_ij 220 | normal_ik = -1*normal_ik 221 | # move each vertex inward along its two edge normals 222 | polygon = points_i - delta*normal_ij - delta*normal_ik 223 | 224 | # In an extreme case of the above, the polygon edge doubles back on 225 | # itself on the same line, resulting in a zero-width segment. I've 226 | # seen this happen, e.g., with a capital "N"-shaped hole, where 227 | # the hole split line cuts out the "N" shape but splits apart to 228 | # form the triangle cutout in one side of the shape. In any case, 229 | # simply moving the polygon edges isn't enough to deal with this; 230 | # we'll additionally mark points just outside of each edge, between 231 | # the original edge and the delta-shifted edge, as outside the polygon. 232 | # These parts will be removed from the triangulation, and this solves 233 | # just this case with no adverse affects elsewhere. 234 | hole_delta = 0.00001 # small fraction of delta 235 | holes = 0.5*(points_j+points_i) - hole_delta*delta*normal_ij 236 | # HOWEVER: sometimes this causes a segmentation fault in the triangle 237 | # library. I've observed this as a result of certain various polygons. 238 | # Frustratingly, the fault can be bypassed by *rotating the polygons* 239 | # by like 30 degrees (exact angle seems to depend on delta values) or 240 | # moving one specific edge outward a bit. I have absolutely no idea 241 | # what is wrong. In the interest of stability over full functionality, 242 | # this is disabled. TODO: figure out why this happens and fix it. 243 | use_holes = False 244 | 245 | # triangulate: compute triangles to fill polygon 246 | point_array = np.arange(num_polygon_points) 247 | edges = np.transpose(np.stack((point_array, np.roll(point_array, 1)))) 248 | if use_holes: 249 | triangles = triangle.triangulate(dict(vertices=polygon, 250 | segments=edges, 251 | holes=holes), opts='p') 252 | else: 253 | triangles = triangle.triangulate(dict(vertices=polygon, 254 | segments=edges), opts='p') 255 | 256 | if not 'triangles' in triangles.keys(): 257 | triangles['triangles'] = [] 258 | 259 | # each line segment will make two triangles (for a rectangle), and the polygon 260 | # triangulation will be copied on the top and bottom of the layer. 261 | num_triangles[layer_number] += num_polygon_points*2 + \ 262 | len(triangles['triangles'])*2 263 | polygons[index] = (polygon, triangles, clockwise) 264 | 265 | 266 | 267 | zmin = layerstack[layer_number]['zmin'] 268 | zmax = layerstack[layer_number]['zmax'] 269 | layername = layerstack[layer_number]['name'] 270 | 271 | print("\nProcesing layer " + layername + "\nExtruding polygons and preparing vertices and faces") 272 | positions = [] 273 | indices = [] 274 | indices_offset = 0 275 | for i,(_, poly_data, clockwise) in enumerate(polygons): 276 | 277 | 278 | p_positions_top = np.insert(poly_data['vertices'], 2, zmax, axis=1) 279 | p_positions_bottom = np.insert( poly_data['vertices'] , 2, zmin, axis=1) 280 | 281 | p_positions = np.concatenate( (p_positions_top, p_positions_bottom) ) 282 | p_indices_top = poly_data['triangles'] 283 | p_indices_bottom = np.flip ((p_indices_top+len(p_positions_top)), axis=1 ) 284 | 285 | ind_list_top = np.arange(len(p_positions_top)) 286 | ind_list_bottom = np.arange(len(p_positions_top)) + len(p_positions_top) 287 | 288 | if(clockwise): 289 | ind_list_top = np.flip(ind_list_top, axis=0) 290 | ind_list_bottom = np.flip(ind_list_bottom, axis=0) 291 | 292 | p_indices_right = np.stack( (ind_list_bottom, np.roll(ind_list_bottom, -1, axis=0) , np.roll(ind_list_top, -1, axis=0)), axis=1 ) 293 | p_indices_left = np.stack( ( np.roll(ind_list_top, -1, axis=0), ind_list_top , ind_list_bottom ) , axis=1) 294 | 295 | p_indices = np.concatenate( (p_indices_top, p_indices_bottom, p_indices_right, p_indices_left) ) 296 | 297 | if(len(positions)==0): 298 | positions = p_positions 299 | else: 300 | positions = np.append(positions , p_positions, axis=0) 301 | if(len(indices)==0): 302 | indices = p_indices 303 | else: 304 | indices = np.append(indices, p_indices + indices_offset, axis=0) 305 | indices_offset += len(p_positions) 306 | 307 | 308 | 309 | 310 | 311 | filename = gdsii_file_path + "_" + layername + '.obj' 312 | print ("Writing layer " + layername + " OBJ file: " + filename) 313 | # filename = cell.name + "_" + layername + '.obj' 314 | object_name = cell.name + "_" + layername 315 | output_file = open(filename, 'w') 316 | output_file.write("# Object name\n") 317 | output_file.write("o " + object_name + "\n") 318 | output_file.write("\n# Vertices\n") 319 | np.savetxt(output_file , positions, delimiter=" ", fmt='v %1.4e %1.4e %1.4e') 320 | 321 | output_file.write("\n# Faces\n") 322 | # add 1 tode indices as OBJ file format starts counting from 1 instead of 0 323 | np.savetxt(output_file , indices + 1, delimiter=" ", fmt='f %d %d %d') 324 | output_file.close() 325 | 326 | print('Done.') 327 | --------------------------------------------------------------------------------