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import struct
normals = []
points = []
triangles = []
triangle_number = 0
def load_binary_stl(fp):
'''
二位元 STL 檔案格式如下:
檔案標頭共有 80 個字元(bytes), 內容通常省略, 但是內容不可使用 solid, 以免與文字檔案 STL 混淆
UINT8[80] – Header
UINT32 – Number of triangles (I:佔 4 bytes 的 unsigned integer)
foreach triangle
REAL32[3] – Normal vector (f:每一座標分量為一佔 4 bytes 的 float, 共佔 12 bytes)
REAL32[3] – Vertex 1
REAL32[3] – Vertex 2
REAL32[3] – Vertex 3
UINT16 – Attribute byte count (H:兩個 bytes 的 unsigned short, 表示 attribute byte count)
end
'''
# 已經在外部開檔
#fp=open(filename,'rb')
header=fp.read(80)
triangle_number = struct.unpack('I',fp.read(4))[0]
#print(triangle_number)
count=0
while True:
try:
p=fp.read(12)
if len(p)==12:
n=[struct.unpack('f',p[0:4])[0],struct.unpack('f',p[4:8])[0],struct.unpack('f',p[8:12])[0]]
normals.append(n)
l = len(points)
#print(n)
p=fp.read(12)
if len(p)==12:
p1=[struct.unpack('f',p[0:4])[0],struct.unpack('f',p[4:8])[0],struct.unpack('f',p[8:12])[0]]
points.append(p1)
#print(p1)
p=fp.read(12)
if len(p)==12:
p2=[struct.unpack('f',p[0:4])[0],struct.unpack('f',p[4:8])[0],struct.unpack('f',p[8:12])[0]]
points.append(p2)
p=fp.read(12)
if len(p)==12:
p3=[struct.unpack('f',p[0:4])[0],struct.unpack('f',p[4:8])[0],struct.unpack('f',p[8:12])[0]]
points.append(p3)
triangles.append((l, l+1, l+2))
# 使用 count 來計算三角形平面個數
# triangle_number 為 STL 檔案中的三角形個數
count += 1
#print(count)
# 在前面 12*4 個 bytes 的 normal 與三個點資料後, 為
# 一個 2 bytes 長的 unsigned short, 其值為零, 為 attribute
fp.read(2)
# 讀完所有三角平面後, 即跳出 while
if count > triangle_number:
break
except EOFError:
break
#fp.close()
def read_length(f):
length = struct.unpack("@i", f.read(4))
return length[0]
def read_header(f):
f.seek(f.tell()+80)
def write_as_ascii(outfilename):
f = open(outfilename, "w")
f.write ("solid "+outfilename+"\n")
for n in range(len(triangles)):
f.write ("facet normal {} {} {}\n".format(normals[n][0],normals[n][1],normals[n][2]))
f.write ("outer loop\n")
f.write ("vertex {} {} {}\n".format(points[triangles[n][0]][0],points[triangles[n][0]][1],points[triangles[n][0]][2]))
f.write ("vertex {} {} {}\n".format(points[triangles[n][1]][0],points[triangles[n][1]][1],points[triangles[n][1]][2]))
f.write ("vertex {} {} {}\n".format(points[triangles[n][2]][0],points[triangles[n][2]][1],points[triangles[n][2]][2]))
f.write ("endloop\n")
f.write ("endfacet\n")
f.write ("endsolid "+outfilename+"\n")
f.close()
def main():
infilename = "spikeball_bin.stl"
outfilename = "spikeball_ascii.stl"
try:
f = open(infilename, "rb")
#read_header(f)
#l = read_length(f)
try:
load_binary_stl(f)
l = len(normals)
except Exception as e:
print("Exception",e)
print(len(normals), len(points), len(triangles), l)
write_as_ascii(outfilename)
print("done")
except Exception as e:
print(e)
if __name__ == '__main__':
main()
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