伪民科小白不容易
– 一段代码改了一周
原始的代码来着cyl_head_bolt.scad
这是原始代码：
module thread(
// the thread is extruded with a twisted linear extrusion
orad=10, // outer diameter of thread
tl=10, // thread length
p=1) // lead of thread
{ // -----------------------------------------------
// radius' for the spiral
r = [orad-0/18*p, orad-1/18*p, orad-2/18*p, orad-3/18*p, orad-4/18*p, orad-5/18*p,
orad-6/18*p, orad-7/18*p, orad-8/18*p, orad-9/18*p, orad-10/18*p, orad-11/18*p,
orad-12/18*p, orad-13/18*p, orad-14/18*p, orad-15/18*p, orad-16/18*p, orad-17/18*p,
orad-p];
// extrude 2d shape with twist
translate([0,0,tl/2])
//difference() {
linear_extrude(height = tl, convexity = 10, twist = -360.0*tl/p, center = true)
// mirrored spiral (2d poly) -> triangular thread when extruded
polygon([[ r[ 0]*cos( 0), r[ 0]*sin( 0)], [r[ 1]*cos( 10), r[ 1]*sin( 10)],
[ r[ 2]*cos( 20), r[ 2]*sin( 20)], [r[ 3]*cos( 30), r[ 3]*sin( 30)],
[ r[ 4]*cos( 40), r[ 4]*sin( 40)], [r[ 5]*cos( 50), r[ 5]*sin( 50)],
[ r[ 6]*cos( 60), r[ 6]*sin( 60)], [r[ 7]*cos( 70), r[ 7]*sin( 70)],
[ r[ 8]*cos( 80), r[ 8]*sin( 80)], [r[ 9]*cos( 90), r[ 9]*sin( 90)],
[ r[10]*cos(100), r[10]*sin(100)], [r[11]*cos(110), r[11]*sin(110)],
[ r[12]*cos(120), r[12]*sin(120)], [r[13]*cos(130), r[13]*sin(130)],
[ r[14]*cos(140), r[14]*sin(140)], [r[15]*cos(150), r[15]*sin(150)],
[ r[16]*cos(160), r[16]*sin(160)], [r[17]*cos(170), r[17]*sin(170)],
[ r[18]*cos(180), r[18]*sin(180)], [r[17]*cos(190), r[17]*sin(190)],
[ r[16]*cos(200), r[16]*sin(200)], [r[15]*cos(210), r[15]*sin(210)],
[ r[14]*cos(220), r[14]*sin(220)], [r[13]*cos(230), r[13]*sin(230)],
[ r[12]*cos(240), r[12]*sin(240)], [r[11]*cos(250), r[11]*sin(250)],
[ r[10]*cos(260), r[10]*sin(260)], [r[ 9]*cos(270), r[ 9]*sin(270)],
[ r[ 8]*cos(280), r[ 8]*sin(280)], [r[ 7]*cos(290), r[ 7]*sin(290)],
[ r[ 6]*cos(300), r[ 6]*sin(300)], [r[ 5]*cos(310), r[ 5]*sin(310)],
[ r[ 4]*cos(320), r[ 4]*sin(320)], [r[ 3]*cos(330), r[ 3]*sin(330)],
[ r[ 2]*cos(340), r[ 2]*sin(340)], [r[ 1]*cos(350), r[ 1]*sin(350)]
]);
}
// -----------------------------
thread();
运行的结果是：
最开始用Py代码优化如下：
def thread(P=1, #螺距,
length=2, #螺丝的总长,
Rmaj=5, #外径,
sn = 36):
angle = 360/sn
Pt = []
for i in range(sn):
if i > round(sn / 2):
i = i - round(sn / 2)
r = Rmaj - i / sn * P
p = [r * cos( i* angle), r * sin(i * angle)]
Pt.append(p)
c = P2(Pt)
c = Le(height = length, convexity = 10, twist = -360.0*length/P,
center = True, slices = 500)(c)
return(c)
成功了吗？
于是想用截面来验证一下：
c = Pr()(Ry(90)(thread()))
c
等了好久没有结果
转化成scad文件看看
c = Pr()(Ry(90)(thread()))
scad_render_to_file(c,"testcc.scad")
得到了这个文件：
projection() {
rotate(a = [0, 90, 0]) {
linear_extrude(center = true, convexity = 10, height = 2, slices = 500, twist = -720.0000000000) {
polygon(paths = [[0, 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]], points = [[5.0000000000, 0.0000000000], [-4.1720501029, -2.7049938569], [2.0177390834, 4.5140070730], [0.7584029619, -4.8578221518], [-3.2605860792, 3.6427754512], [4.6908070829, -1.2754333166], [-4.6033294053, -1.4732513353], [3.0434506148, 3.7189746642], [-0.5274057206, -4.7485791243], [-2.1283496766, 4.2464841521], [4.0720613414, -2.3911710830], [-4.6898477069, -0.2076947943], [3.7995111958, 2.7095188597], [-1.7038236718, -4.3146581578], [-0.9121403690, 4.5199939852], [3.2048995297, -3.2765169691], [-4.4445335361, 0.9996039548], [4.2470317943, 1.5695517013], [-2.6930703108, -3.6051868608], [-4.1720501029, -2.7049938569], [2.0177390834, 4.5140070730], [0.7584029619, -4.8578221518], [-3.2605860792, 3.6427754512], [4.6908070829, -1.2754333166], [-4.6033294053, -1.4732513353], [3.0434506148, 3.7189746642], [-0.5274057206, -4.7485791243], [-2.1283496766, 4.2464841521], [4.0720613414, -2.3911710830], [-4.6898477069, -0.2076947943], [3.7995111958, 2.7095188597], [-1.7038236718, -4.3146581578], [-0.9121403690, 4.5199939852], [3.2048995297, -3.2765169691], [-4.4445335361, 0.9996039548], [4.2470317943, 1.5695517013]]);
}
}
}
还是打不开，电脑不给力吗？用MacBook Pro试了一下还是不成功！！！
开始想到去网上问问：
Try open this file, preview or render failed, what’s wrong??
没有结果。。。
再问！
Try open this file, preview or render failed, what’s wrong??
好吧！终于找到原因了，原来在py中计算三角函数是不能用角度–和openscad不一样–只能用弧度。
修改后得到如下结果：
好逊，还是不对呀。。。
还有问题。。。似乎是这段代码
这么改一下：
def thread(P=1, #螺距,
length=2, #螺丝的总长,
Rmaj=5, #外径,
sn = 36):
angle = 2 * pi/sn
Pt = []
for i in range(0,sn-1):
if i > round(sn / 2):
i = sn - i
r = Rmaj - i / sn * P
p = [r * cos( i* angle), r * sin(i * angle)]
Pt.append(p)
c = P2(Pt)
c = Le(height = length, convexity = 10, twist = -360.0*length/P,
center = True, slices = 500)(c)
# print(scad_render(c))
# r.render(c)
# print(Pt)
return(c)
结果：
好奇怪呀？哪里出错了呢？
把scad原始代码py化：
def thread(
# the thread is extruded with a twisted linear extrusion
Dmaj, # outer diameter of thread
length, # thread length
P): # lead of thread
# radius’ for the spiral
r = [Dmaj-0/18*P, Dmaj-1/18*P, Dmaj-2/18*P, Dmaj-3/18*P, Dmaj-4/18*P, Dmaj-5/18*P,
Dmaj-6/18*P, Dmaj-7/18*P, Dmaj-8/18*P, Dmaj-9/18*P, Dmaj-10/18*P, Dmaj-11/18*P,
Dmaj-12/18*P, Dmaj-13/18*P, Dmaj-14/18*P, Dmaj-15/18*P, Dmaj-16/18*P, Dmaj-17/18*P,
Dmaj-P]
# extrude 2d shape with twist
# translate([0,0,length/2])
#difference() {
c = linear_extrude(height = length, convexity = 10, twist = -360.0*length/P, center = True)(
# mirrored spiral (2d poly) -> triangular thread when extruded
polygon([[ r[ 0]*cos( 0/36*2*pi), r[ 0]*sin( 0/36*2*pi)], [r[ 1]*cos( 1/36*2*pi), r[ 1]*sin( 1/36*2*pi)],
[ r[ 2]*cos( 2/36*2*pi), r[ 2]*sin( 2/36*2*pi)], [r[ 3]*cos( 3/36*2*pi), r[ 3]*sin( 3/36*2*pi)],
[ r[ 4]*cos( 4/36*2*pi), r[ 4]*sin( 4/36*2*pi)], [r[ 5]*cos( 5/36*2*pi), r[ 5]*sin( 5/36*2*pi)],
[ r[ 6]*cos( 6/36*2*pi), r[ 6]*sin( 6/36*2*pi)], [r[ 7]*cos( 7/36*2*pi), r[ 7]*sin( 7/36*2*pi)],
[ r[ 8]*cos( 8/36*2*pi), r[ 8]*sin( 8/36*2*pi)], [r[ 9]*cos( 9/36*2*pi), r[ 9]*sin( 9/36*2*pi)],
[ r[10]*cos(10/36*2*pi), r[10]*sin(10/36*2*pi)], [r[11]*cos(11/36*2*pi), r[11]*sin(11/36*2*pi)],
[ r[12]*cos(12/36*2*pi), r[12]*sin(12/36*2*pi)], [r[13]*cos(13/36*2*pi), r[13]*sin(13/36*2*pi)],
[ r[14]*cos(14/36*2*pi), r[14]*sin(14/36*2*pi)], [r[15]*cos(15/36*2*pi), r[15]*sin(15/36*2*pi)],
[ r[16]*cos(16/36*2*pi), r[16]*sin(16/36*2*pi)], [r[17]*cos(17/36*2*pi), r[17]*sin(17/36*2*pi)],
[ r[18]*cos(18/36*2*pi), r[18]*sin(18/36*2*pi)], [r[17]*cos(19/36*2*pi), r[17]*sin(19/36*2*pi)],
[ r[16]*cos(20/36*2*pi), r[16]*sin(20/36*2*pi)], [r[15]*cos(21/36*2*pi), r[15]*sin(21/36*2*pi)],
[ r[14]*cos(22/36*2*pi), r[14]*sin(22/36*2*pi)], [r[13]*cos(23/36*2*pi), r[13]*sin(23/36*2*pi)],
[ r[12]*cos(24/36*2*pi), r[12]*sin(24/36*2*pi)], [r[11]*cos(25/36*2*pi), r[11]*sin(25/36*2*pi)],
[ r[10]*cos(26/36*2*pi), r[10]*sin(26/36*2*pi)], [r[ 9]*cos(27/36*2*pi), r[ 9]*sin(27/36*2*pi)],
[ r[ 8]*cos(28/36*2*pi), r[ 8]*sin(28/36*2*pi)], [r[ 7]*cos(29/36*2*pi), r[ 7]*sin(29/36*2*pi)],
[ r[ 6]*cos(30/36*2*pi), r[ 6]*sin(30/36*2*pi)], [r[ 5]*cos(31/36*2*pi), r[ 5]*sin(31/36*2*pi)],
[ r[ 4]*cos(32/36*2*pi), r[ 4]*sin(32/36*2*pi)], [r[ 3]*cos(33/36*2*pi), r[ 3]*sin(33/36*2*pi)],
[ r[ 2]*cos(34/36*2*pi), r[ 2]*sin(34/36*2*pi)], [r[ 1]*cos(35/36*2*pi), r[ 1]*sin(35/36*2*pi)]])
)
return(c)
还好：
请教了高手
终于解决：
def thread(P=1, #螺距,
length=10, #螺丝的总长,
Rmaj=10, #外径,
sn = 36):
angle = 2 * pi/sn
Pt = []
for i in range(0,sn-1):
j = i #新增变量，防止流程改变
if i > round(sn / 2):
j = sn - i
r = Rmaj - j / sn * P * 2
p = [r * cos( i* angle), r * sin(i * angle)]
Pt.append(p)
# c = P2(Pt)
c = linear_extrude(height = length, convexity = 10, twist = -360.0*length/P, center = True)(P2(Pt))
# print(scad_render(c))
# r.render(c)
print(Pt)
return(c)
c = thread()
c
总结一下：
- 在py中三角函数要用弧度
- 在py中for循环时注意，作为控制流程的变量i，从始至终要流畅，对于有可能改变流程的过程中，再加入一个（我称之为）执行变量j，是个聪明的办法；
- 注意：range的范围，给定的终止数值并不在要生成的序列里；
记下来，以上。。。
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