Hi,

I am new to OpenSCAD, and I built a polyhedron which I can render with no problem.

However, when I try to substract a cylinder from it, I can visualize it (F5), but not render it (F6): the resulting render is empty. I have seen some similar problems from other people, but usually when importing stl files. The code is below (sorry for the complexity, the shape of the polyhedron was generated from outside).

Is there something wrong with the code? Do you encounter the same issue?

Thanks for any help,

Sébastien

difference() {
polyhedron(faces = [[19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0], [0, 1, 21, 20], [1, 2, 22, 21], [2, 3, 23, 22], [3, 4, 24, 23], [4, 5, 25, 24], [5, 6, 26, 25], [6, 7, 27, 26], [7, 8, 28, 27], [8, 9, 29, 28], [9, 10, 30, 29], [10, 11, 31, 30], [11, 12, 32, 31], [12, 13, 33, 32], [13, 14, 34, 33], [14, 15, 35, 34], [15, 16, 36, 35], [16, 17, 37, 36], [17, 18, 38, 37], [18, 19, 39, 38], [19, 0, 20, 39], [20, 21, 41, 40], [21, 22, 42, 41], [22, 23, 43, 42], [23, 24, 44, 43], [24, 25, 45, 44], [25, 26, 46, 45], [26, 27, 47, 46], [27, 28, 48, 47], [28, 29, 49, 48], [29, 30, 50, 49], [30, 31, 51, 50], [31, 32, 52, 51], [32, 33, 53, 52], [33, 34, 54, 53], [34, 35, 55, 54], [35, 36, 56, 55], [36, 37, 57, 56], [37, 38, 58, 57], [38, 39, 59, 58], [39, 20, 40, 59], [40, 41, 61, 60], [41, 42, 62, 61], [42, 43, 63, 62], [43, 44, 64, 63], [44, 45, 65, 64], [45, 46, 66, 65], [46, 47, 67, 66], [47, 48, 68, 67], [48, 49, 69, 68], [49, 50, 70, 69], [50, 51, 71, 70], [51, 52, 72, 71], [52, 53, 73, 72], [53, 54, 74, 73], [54, 55, 75, 74], [55, 56, 76, 75], [56, 57, 77, 76], [57, 58, 78, 77], [58, 59, 79, 78], [59, 40, 60, 79], [60, 61, 81, 80], [61, 62, 82, 81], [62, 63, 83, 82], [63, 64, 84, 83], [64, 65, 85, 84], [65, 66, 86, 85], [66, 67, 87, 86], [67, 68, 88, 87], [68, 69, 89, 88], [69, 70, 90, 89], [70, 71, 91, 90], [71, 72, 92, 91], [72, 73, 93, 92], [73, 74, 94, 93], [74, 75, 95, 94], [75, 76, 96, 95], [76, 77, 97, 96], [77, 78, 98, 97], [78, 79, 99, 98], [79, 60, 80, 99], [80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]], points = [[-12.1000000000, 0.6000000000, 2.4733413149], [-0.2645497289, -0.0128808879, 2.4733413149], [11.9344341747, -1.4086239445, 2.4733413149], [24.1355716448, -2.5542701643, 2.4733413149], [35.9774826150, -2.4168605418, 2.4733413149], [47.0987871087, 0.0365636260, 2.4733413149], [57.2529612666, 5.4496843894, 2.4733413149], [66.6402934955, 12.9518231698, 2.4733413149], [75.5697083075, 21.3041059427, 2.4733413149], [84.3501302148, 29.2676586838, 2.4733413149], [84.9947208658, 28.5062359773, 2.4733413149], [76.1429723223, 20.4779923324, 2.4733413149], [67.1410205492, 12.0578608568, 2.4733413149], [57.6774315256, 4.4947794099, 2.4733413149], [47.4407712304, -0.9623141489, 2.4733413149], [36.2291242397, -3.4356683946, 2.4733413149], [24.2910170177, -3.5741942466, 2.4733413149], [11.9907651653, -2.4192415160, 2.4733413149], [-0.3073156265, -1.0121603189, 2.4733413149], [-12.2389096666, -0.3943007714, 2.4733413149], [-12.1000000000, 0.1270378309, 7.4767584377], [-0.2645497289, -0.4858430570, 7.4767584377], [11.9344341747, -1.8815861136, 7.4767584377], [24.1355716448, -3.0272323334, 7.4767584377], [35.9774826150, -2.8898227109, 7.4767584377], [47.0987871087, -0.4363985431, 7.4767584377], [57.2529612666, 4.9767222203, 7.4767584377], [66.6402934955, 12.4788610007, 7.4767584377], [75.5697083075, 20.8311437736, 7.4767584377], [84.3501302148, 28.7946965147, 7.4767584377], [84.9947208658, 28.0332738082, 7.4767584377], [78.3312410826, 16.8515815611, 7.4767584377], [69.1485014005, 8.0008857770, 7.4767584377], [59.2936304543, 0.3859526016, 7.4767584377], [48.7084326467, -5.1379008975, 7.4767584377], [37.1619054951, -7.6851316458, 7.4767584377], [24.8828856821, -7.9305856419, 7.4767584377], [12.2166035420, -6.9439029250, 7.4767584377], [-0.4705620106, -5.2995812809, 7.4767584377], [-12.2389096666, -0.8672629405, 7.4767584377], [-12.1000000000, -0.0308238948, 12.5000000000], [-0.2645497289, -0.6437047827, 12.5000000000], [11.9344341747, -2.0394478393, 12.5000000000], [24.1355716448, -3.1850940591, 12.5000000000], [35.9774826150, -3.0476844366, 12.5000000000], [47.0987871087, -0.5942602689, 12.5000000000], [57.2529612666, 4.8188604946, 12.5000000000], [66.6402934955, 12.3209992750, 12.5000000000], [75.5697083075, 20.6732820479, 12.5000000000], [84.3501302148, 28.6368347890, 12.5000000000], [84.9947208658, 27.8754120825, 12.5000000000], [78.9262963850, 15.8362034527, 12.5000000000], [69.6943950981, 6.8684244385, 12.5000000000], [59.7331229699, -0.7606087627, 12.5000000000], [49.0531474556, -6.3026162734, 12.5000000000], [37.4155564369, -8.8699362381, 12.5000000000], [25.0438323598, -9.1444671741, 12.5000000000], [12.2780157076, -8.2035420741, 12.5000000000], [-0.5149535534, -6.4947077026, 12.5000000000], [-12.2389096666, -1.0251246662, 12.5000000000], [-12.1000000000, 0.1270378309, 17.5232415623], [-0.2645497289, -0.4858430570, 17.5232415623], [11.9344341747, -1.8815861136, 17.5232415623], [24.1355716448, -3.0272323334, 17.5232415623], [35.9774826150, -2.8898227109, 17.5232415623], [47.0987871087, -0.4363985431, 17.5232415623], [57.2529612666, 4.9767222203, 17.5232415623], [66.6402934955, 12.4788610007, 17.5232415623], [75.5697083075, 20.8311437736, 17.5232415623], [84.3501302148, 28.7946965147, 17.5232415623], [84.9947208658, 28.0332738082, 17.5232415623], [78.7634496000, 16.2287388054, 17.5232415623], [69.5450022043, 7.2930015653, 17.5232415623], [59.6128485300, -0.3321729292, 17.5232415623], [48.9588105122, -5.8692122925, 17.5232415623], [37.3461406360, -8.4310345089, 17.5232415623], [24.9997866233, -8.6976080565, 17.5232415623], [12.2612092466, -7.7441606233, 17.5232415623], [-0.5028050691, -6.0529812331, 17.5232415623], [-12.2389096666, -0.8672629405, 17.5232415623], [-12.1000000000, 0.6000000000, 22.5266586851], [-0.2645497289, -0.0128808879, 22.5266586851], [11.9344341747, -1.4086239445, 22.5266586851], [24.1355716448, -2.5542701643, 22.5266586851], [35.9774826150, -2.4168605418, 22.5266586851], [47.0987871087, 0.0365636260, 22.5266586851], [57.2529612666, 5.4496843894, 22.5266586851], [66.6402934955, 12.9518231698, 22.5266586851], [75.5697083075, 21.3041059427, 22.5266586851], [84.3501302148, 29.2676586838, 22.5266586851], [84.9947208658, 28.5062359773, 22.5266586851], [77.4852411417, 18.5436889190, 22.5266586851], [68.3723953242, 9.8594522949, 22.5266586851], [58.6687966940, 2.2645653588, 22.5266586851], [48.2183459157, -3.2334782825, 22.5266586851], [36.8012857663, -5.7521478605, 22.5266586851], [24.6540651349, -5.9562626915, 22.5266586851], [12.1292928529, -4.9045256155, 22.5266586851], [-0.4074498217, -3.3519227802, 22.5266586851], [-12.2389096666, -0.3943007714, 22.5266586851]]);
translate(v = [5.0, 123.0, 12.5]) {
rotate(a = 90, v = [103.5000000000, 69.1691761052]) {
cylinder(d = 10, h = 127.185440606789);
}
}
}

It seems rendering just fine on my OpenSCAD version 2017.01.20 (git 59df0d1)
(windows 10)

$  Runsun Pan, PhD $ libs: scadx , doctest , faces ( git ), offline doc ( git ), runscad.py ( 2 , git ), editor of choice: CudaText  ( OpenSCAD lexer ); $ Tips ; $ Snippets

--
Sent from: http://forum.openscad.org/

Thanks for pointing out the cause of the issue. I did not realized that my algorithm was producing non-planar faces, but now i understand why.

Indeed fixed with the latest version, but I will switch to triangles.

----- Mail original -----

De: "Hans L" thehans@gmail.com
À: "OpenSCAD general discussion" discuss@lists.openscad.org
Envoyé: Lundi 29 Octobre 2018 19:26:21
Objet: <DKIM> Re: [OpenSCAD] No rendering when using difference

It looks like you are using quads for most of the polyhedron (except for the top and bottom faces), but it appears that quads on the end are not planar.
You should split these bits into triangles to avoid any issues like this.

With that being said, it does appear to render fine for me on Windows, using a dev snapshot 2018.06.01 (git 4455a12)

It does give a warning but seems to be able to handle working around it:

"PolySet has nonplanar faces. Attempting alternate construction"

On Mon, Oct 29, 2018 at 12:14 PM < seb.belese@laposte.net > wrote:

Hi,

I am new to OpenSCAD, and I built a polyhedron which I can render with no problem.

However, when I try to substract a cylinder from it, I can visualize it (F5), but not render it (F6): the resulting render is empty. I have seen some similar problems from other people, but usually when importing stl files. The code is below (sorry for the complexity, the shape of the polyhedron was generated from outside).

Is there something wrong with the code? Do you encounter the same issue?

Thanks for any help,

Sébastien

difference() {
polyhedron(faces = [[19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0], [0, 1, 21, 20], [1, 2, 22, 21], [2, 3, 23, 22], [3, 4, 24, 23], [4, 5, 25, 24], [5, 6, 26, 25], [6, 7, 27, 26], [7, 8, 28, 27], [8, 9, 29, 28], [9, 10, 30, 29], [10, 11, 31, 30], [11, 12, 32, 31], [12, 13, 33, 32], [13, 14, 34, 33], [14, 15, 35, 34], [15, 16, 36, 35], [16, 17, 37, 36], [17, 18, 38, 37], [18, 19, 39, 38], [19, 0, 20, 39], [20, 21, 41, 40], [21, 22, 42, 41], [22, 23, 43, 42], [23, 24, 44, 43], [24, 25, 45, 44], [25, 26, 46, 45], [26, 27, 47, 46], [27, 28, 48, 47], [28, 29, 49, 48], [29, 30, 50, 49], [30, 31, 51, 50], [31, 32, 52, 51], [32, 33, 53, 52], [33, 34, 54, 53], [34, 35, 55, 54], [35, 36, 56, 55], [36, 37, 57, 56], [37, 38, 58, 57], [38, 39, 59, 58], [39, 20, 40, 59], [40, 41, 61, 60], [41, 42, 62, 61], [42, 43, 63, 62], [43, 44, 64, 63], [44, 45, 65, 64], [45, 46, 66, 65], [46, 47, 67, 66], [47, 48, 68, 67], [48, 49, 69, 68], [49, 50, 70, 69], [50, 51, 71, 70], [51, 52, 72, 71], [52, 53, 73, 72], [53, 54, 74, 73], [54, 55, 75, 74], [55, 56, 76, 75], [56, 57, 77, 76], [57, 58, 78, 77], [58, 59, 79, 78], [59, 40, 60, 79], [60, 61, 81, 80], [61, 62, 82, 81], [62, 63, 83, 82], [63, 64, 84, 83], [64, 65, 85, 84], [65, 66, 86, 85], [66, 67, 87, 86], [67, 68, 88, 87], [68, 69, 89, 88], [69, 70, 90, 89], [70, 71, 91, 90], [71, 72, 92, 91], [72, 73, 93, 92], [73, 74, 94, 93], [74, 75, 95, 94], [75, 76, 96, 95], [76, 77, 97, 96], [77, 78, 98, 97], [78, 79, 99, 98], [79, 60, 80, 99], [80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]], points = [[-12.1000000000, 0.6000000000, 2.4733413149], [-0.2645497289, -0.0128808879, 2.4733413149], [11.9344341747, -1.4086239445, 2.4733413149], [24.1355716448, -2.5542701643, 2.4733413149], [35.9774826150, -2.4168605418, 2.4733413149], [47.0987871087, 0.0365636260, 2.4733413149], [57.2529612666, 5.4496843894, 2.4733413149], [66.6402934955, 12.9518231698, 2.4733413149], [75.5697083075, 21.3041059427, 2.4733413149], [84.3501302148, 29.2676586838, 2.4733413149], [84.9947208658, 28.5062359773, 2.4733413149], [76.1429723223, 20.4779923324, 2.4733413149], [67.1410205492, 12.0578608568, 2.4733413149], [57.6774315256, 4.4947794099, 2.4733413149], [47.4407712304, -0.9623141489, 2.4733413149], [36.2291242397, -3.4356683946, 2.4733413149], [24.2910170177, -3.5741942466, 2.4733413149], [11.9907651653, -2.4192415160, 2.4733413149], [-0.3073156265, -1.0121603189, 2.4733413149], [-12.2389096666, -0.3943007714, 2.4733413149], [-12.1000000000, 0.1270378309, 7.4767584377], [-0.2645497289, -0.4858430570, 7.4767584377], [11.9344341747, -1.8815861136, 7.4767584377], [24.1355716448, -3.0272323334, 7.4767584377], [35.9774826150, -2.8898227109, 7.4767584377], [47.0987871087, -0.4363985431, 7.4767584377], [57.2529612666, 4.9767222203, 7.4767584377], [66.6402934955, 12.4788610007, 7.4767584377], [75.5697083075, 20.8311437736, 7.4767584377], [84.3501302148, 28.7946965147, 7.4767584377], [84.9947208658, 28.0332738082, 7.4767584377], [78.3312410826, 16.8515815611, 7.4767584377], [69.1485014005, 8.0008857770, 7.4767584377], [59.2936304543, 0.3859526016, 7.4767584377], [48.7084326467, -5.1379008975, 7.4767584377], [37.1619054951, -7.6851316458, 7.4767584377], [24.8828856821, -7.9305856419, 7.4767584377], [12.2166035420, -6.9439029250, 7.4767584377], [-0.4705620106, -5.2995812809, 7.4767584377], [-12.2389096666, -0.8672629405, 7.4767584377], [-12.1000000000, -0.0308238948, 12.5000000000], [-0.2645497289, -0.6437047827, 12.5000000000], [11.9344341747, -2.0394478393, 12.5000000000], [24.1355716448, -3.1850940591, 12.5000000000], [35.9774826150, -3.0476844366, 12.5000000000], [47.0987871087, -0.5942602689, 12.5000000000], [57.2529612666, 4.8188604946, 12.5000000000], [66.6402934955, 12.3209992750, 12.5000000000], [75.5697083075, 20.6732820479, 12.5000000000], [84.3501302148, 28.6368347890, 12.5000000000], [84.9947208658, 27.8754120825, 12.5000000000], [78.9262963850, 15.8362034527, 12.5000000000], [69.6943950981, 6.8684244385, 12.5000000000], [59.7331229699, -0.7606087627, 12.5000000000], [49.0531474556, -6.3026162734, 12.5000000000], [37.4155564369, -8.8699362381, 12.5000000000], [25.0438323598, -9.1444671741, 12.5000000000], [12.2780157076, -8.2035420741, 12.5000000000], [-0.5149535534, -6.4947077026, 12.5000000000], [-12.2389096666, -1.0251246662, 12.5000000000], [-12.1000000000, 0.1270378309, 17.5232415623], [-0.2645497289, -0.4858430570, 17.5232415623], [11.9344341747, -1.8815861136, 17.5232415623], [24.1355716448, -3.0272323334, 17.5232415623], [35.9774826150, -2.8898227109, 17.5232415623], [47.0987871087, -0.4363985431, 17.5232415623], [57.2529612666, 4.9767222203, 17.5232415623], [66.6402934955, 12.4788610007, 17.5232415623], [75.5697083075, 20.8311437736, 17.5232415623], [84.3501302148, 28.7946965147, 17.5232415623], [84.9947208658, 28.0332738082, 17.5232415623], [78.7634496000, 16.2287388054, 17.5232415623], [69.5450022043, 7.2930015653, 17.5232415623], [59.6128485300, -0.3321729292, 17.5232415623], [48.9588105122, -5.8692122925, 17.5232415623], [37.3461406360, -8.4310345089, 17.5232415623], [24.9997866233, -8.6976080565, 17.5232415623], [12.2612092466, -7.7441606233, 17.5232415623], [-0.5028050691, -6.0529812331, 17.5232415623], [-12.2389096666, -0.8672629405, 17.5232415623], [-12.1000000000, 0.6000000000, 22.5266586851], [-0.2645497289, -0.0128808879, 22.5266586851], [11.9344341747, -1.4086239445, 22.5266586851], [24.1355716448, -2.5542701643, 22.5266586851], [35.9774826150, -2.4168605418, 22.5266586851], [47.0987871087, 0.0365636260, 22.5266586851], [57.2529612666, 5.4496843894, 22.5266586851], [66.6402934955, 12.9518231698, 22.5266586851], [75.5697083075, 21.3041059427, 22.5266586851], [84.3501302148, 29.2676586838, 22.5266586851], [84.9947208658, 28.5062359773, 22.5266586851], [77.4852411417, 18.5436889190, 22.5266586851], [68.3723953242, 9.8594522949, 22.5266586851], [58.6687966940, 2.2645653588, 22.5266586851], [48.2183459157, -3.2334782825, 22.5266586851], [36.8012857663, -5.7521478605, 22.5266586851], [24.6540651349, -5.9562626915, 22.5266586851], [12.1292928529, -4.9045256155, 22.5266586851], [-0.4074498217, -3.3519227802, 22.5266586851], [-12.2389096666, -0.3943007714, 22.5266586851]]);
translate(v = [5.0, 123.0, 12.5]) {
rotate(a = 90, v = [103.5000000000, 69.1691761052]) {
cylinder(d = 10, h = 127.185440606789);
}
}
}

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