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Author: BruceSherwood

Demos_no_notebook/convert_stl/Part1_bin.stl

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+# UINT8[80]    – Header                 -     80 bytes                           
+# UINT32       – Number of triangles    -      4 bytes
+# foreach triangle                      - 50 bytes:
+    # REAL32[3] – Normal vector             - 12 bytes
+    # REAL32[3] – Vertex 1                  - 12 bytes
+    # REAL32[3] – Vertex 2                  - 12 bytes
+    # REAL32[3] – Vertex 3                  - 12 bytes
+    # UINT16    – Attribute byte count      -  2 bytes
+# end
+
+from vpython import *
+import struct
+from collections import namedtuple
+import numpy as np
+
+Ctypes = namedtuple('Ctype', ['fmt', 'size'])
+
+Ctype_names = ['char', 'signed char', 'unsigned char', '_Bool', 'short', \
+               'unsigned short', 'int', 'unsigned int', 'long', 'unsigned long',\
+                   'long long', 'unsigned long long', 'float', 'double', 'char[]']
+Ctype_sizes = [1, 1, 1, 1, 2,\
+              2, 4, 4, 4, 4,\
+                  8, 8, 4, 8, -1]
+Ctype_formats = ['c', 'b', 'B', '?', 'h',\
+                'H', 'i', 'I', 'l', 'L',\
+                    'q', 'Q', 'f', 'd', 's']
+
+Ctype_dict = {}
+for i, name in enumerate(Ctype_names):
+    Ctype_dict[name] = Ctypes(Ctype_formats[i], Ctype_sizes[i])    
+   
+def binary_reader(fid, Ctype, **opts):
+    assert Ctype in Ctype_dict, "Ctype not found in Ctype_dict"
+    if Ctype == 'char[]':  
+        string = []       
+        for ch in range(opts['size']):
+            char = struct.unpack(Ctype_dict['char'].fmt, fid.read(Ctype_dict['char'].size))[0]            
+            if chr(0).encode('utf-8') not in char:
+                string.append(char.decode('utf-8'))
+            else:
+                string.append(' ')                 
+        return ''.join(string)
+   
+    if Ctype == 'char':
+        return ord(struct.unpack(Ctype_dict[Ctype].fmt, fid.read(Ctype_dict[Ctype].size))[0].decode('utf-8'))   
+    return struct.unpack(Ctype_dict[Ctype].fmt, fid.read(Ctype_dict[Ctype].size))[0]
+    
+def stl_to_triangles(filename):
+    with open(filename, "rb") as f:
+        header = binary_reader(f,'char[]', size = 80)    
+        numOfTri = binary_reader(f,'unsigned int')
+        
+        print(header)
+        print(numOfTri)
+        
+        tris = []
+        
+        for i in range(numOfTri):
+            vs = []
+            x1, x2, x3 = binary_reader(f,'float'), binary_reader(f,'float'), binary_reader(f,'float')
+            N = vec(x1, x2, x3)
+            
+            x1, x2, x3 = binary_reader(f,'float'), binary_reader(f,'float'), binary_reader(f,'float')
+            p1 = vertex(pos = vec(x1, x2, x3), normal=N, color=color.white)
+            vs.append(p1)
+            
+            x1, x2, x3 = binary_reader(f,'float'), binary_reader(f,'float'), binary_reader(f,'float')
+            p2 = vertex(pos = vec(x1, x2, x3), normal=N, color=color.white)
+            vs.append(p2)
+            
+            x1, x2, x3 = binary_reader(f,'float'), binary_reader(f,'float'), binary_reader(f,'float')
+            p3 = vertex(pos = vec(x1, x2, x3), normal=N, color=color.white)
+            vs.append(p3)
+                    
+            attr = binary_reader(f,'unsigned short')    
+            tris.append(triangle(vs=vs))   
+        
+        return compound(tris)
+    
+if __name__ == '__main__':
+    filename = r"\convert_stl\Part1_bin.stl" # update this file
+    man = stl_to_triangles(filename)
+    man.color = color.orange
+    
+    
+