{"topic":{"id":13875,"title":"2.10 各向同性重网络化","slug":"topic","categoryId":56,"createdAt":"2024-11-18 09:00:12.516638","bumpedAt":"2024-11-19 13:42:12.85742","views":186,"postsCount":3,"highestPostNumber":3,"likeCount":0,"closed":false,"pinned":false,"pinnedGlobally":false,"pinnedAt":null,"pinnedUntil":null,"isBanner":false,"excerpt":"我在 2.10 各向同性重网络化坍缩某些边的时候遇到了卡死的问题，这个问题比较奇怪，有些边可以坍缩成功，另一些边就会卡死。我的思路是先把要坍缩和分裂的边放到 set 里面，而且我也考虑了如果坍缩后临边大于 4/3 L 的情况，不大于才放进 set 中， printf(\"Sucsess1\\n\"); // Process selected edges: split or collapse them for (Edge* e : selec…","deletedAt":null,"isAnonymous":false,"category":{"id":56,"name":"计算机图形学","slug":"cg","color":"92278F"},"author":{"id":6145,"username":"SunXueHao","name":"rss","avatarUrl":null},"tags":[]},"posts":[{"id":43354,"postNumber":1,"raw":"我在 2.10 各向同性重网络化坍缩某些边的时候遇到了卡死的问题，这个问题比较奇怪，有些边可以坍缩成功，另一些边就会卡死。\n我的思路是先把要坍缩和分裂的边放到 set 里面，而且我也考虑了如果坍缩后临边大于 4/3 L 的情况，不大于才放进 set 中，\n```\nprintf(\"Sucsess1\\n\");\n // Process selected edges: split or collapse them\n for (Edge* e : selected_edges)\n {\n if (e->length() < EdgeMeanLength * 4.0f / 5.0f)\n {\n printf(\"Attempting to collapse edge: %zu\\n\", e->id);\n collapse_edge(e);\n printf(\"Collapse successful: %zu\\n\", e->id);\n }\n else if (e->length() > EdgeMeanLength * 4.0f / 3.0f)\n {\n split_edge(e);\n printf(\"Sucsess split\\n\");\n }\n }\n printf(\"Sucsess2\\n\");\n```\n但是我执行操作的时候前面坍缩都很好，但是到了某条边就直接卡住了，是在判断坍缩安全性的时候。\n```\nint coVertex = 0;//共同顶点的个数\n Halfedge* hm = v1->halfedge;\n do\n {\n Halfedge* hn = v2->halfedge;\n do\n {\n if(hm->inv->from == hn->inv->from)\n {\n coVertex++;\n }\n hn = hn->inv->next;\n } while (hn != v2->halfedge);\n hm = hm->inv->next;\n } while (hm != v1->halfedge);\n printf(\"success 1\\n\");\n if(coVertex == 2)\n {\n```\n虽然笨，但是感觉这个双循环也是一种求共同顶点的办法。\n![undefined|483x496, 75%](/uploads/image/be/9c/be9c90cc72d255492af2bc4ff0868c421f35e143a6231c294a8e40d381c4a696.avif)\n\n他会卡死在内层循环，其中 printf 用来调试。我曾尝试打印半边的地址，发现他们一直循环，这样的话他应该会在 hn != v2->halfedge 跳出循环才对，但是没有这么做。有点不理解为什么有的边就可以坍缩成功，有的就不行并卡死在寻找共同顶点的 do while 循环中。\n或者说，还有更好的寻找共同顶点的办法？\n这个 12582 边不是边界边","cooked":"

我在 2.10 各向同性重网络化坍缩某些边的时候遇到了卡死的问题，这个问题比较奇怪，有些边可以坍缩成功，另一些边就会卡死。
\n我的思路是先把要坍缩和分裂的边放到 set 里面，而且我也考虑了如果坍缩后临边大于 4/3 L 的情况，不大于才放进 set 中，

printf(\"Sucsess1\\n\");\n        // Process selected edges: split or collapse them\n        for (Edge* e : selected_edges)\n        {\n            if (e->length() < EdgeMeanLength * 4.0f / 5.0f)\n            {\n                printf(\"Attempting to collapse edge: %zu\\n\", e->id);\n                collapse_edge(e);\n                printf(\"Collapse successful: %zu\\n\", e->id);\n            }\n            else if (e->length() > EdgeMeanLength * 4.0f / 3.0f)\n            {\n                split_edge(e);\n                printf(\"Sucsess split\\n\");\n            }\n        }\n        printf(\"Sucsess2\\n\");\n

但是我执行操作的时候前面坍缩都很好，但是到了某条边就直接卡住了，是在判断坍缩安全性的时候。

int coVertex = 0;//共同顶点的个数\n    Halfedge* hm = v1->halfedge;\n        do\n        {\n            Halfedge* hn = v2->halfedge;\n            do\n            {\n                if(hm->inv->from == hn->inv->from)\n                {\n                    coVertex++;\n                }\n                hn = hn->inv->next;\n            } while (hn != v2->halfedge);\n            hm = hm->inv->next;\n        } while (hm != v1->halfedge);\n    printf(\"success 1\\n\");\n    if(coVertex == 2)\n    {\n

虽然笨，但是感觉这个双循环也是一种求共同顶点的办法。
\n $\"undefined\"$

他会卡死在内层循环，其中 printf 用来调试。我曾尝试打印半边的地址，发现他们一直循环，这样的话他应该会在 hn != v2->halfedge 跳出循环才对，但是没有这么做。有点不理解为什么有的边就可以坍缩成功，有的就不行并卡死在寻找共同顶点的 do while 循环中。
\n或者说，还有更好的寻找共同顶点的办法？
\n这个 12582 边不是边界边

\n","createdAt":"2024-11-18 09:00:12.80433","updatedAt":"2024-11-18 09:00:12.80433","replyToPostNumber":null,"replyCount":0,"likeCount":0,"wordCount":423,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":6145,"username":"SunXueHao","name":"rss","avatarUrl":null,"admin":false,"moderator":false,"signatureRaw":null,"signatureCooked":null}},{"id":43363,"postNumber":2,"raw":"这处死循环可能是因为你在尝试 collapse 一条已经被 erase 过的边，因为我遇到过。\n具体来说，在你的代码中，一次 collapse_edge(e) 会 erase 包括 e 在内总计 3 条 edge，那如果除了 e 之外，另外两条边也在 selected_edge 里的话，就会出现这个错误。\n此外，这种错误靠 validate() 检查不出来，因为它本身已经不在网格里了。","cooked":"

这处死循环可能是因为你在尝试 collapse 一条已经被 erase 过的边，因为我遇到过。
\n具体来说，在你的代码中，一次 collapse_edge(e) 会 erase 包括 e 在内总计 3 条 edge，那如果除了 e 之外，另外两条边也在 selected_edge 里的话，就会出现这个错误。
\n此外，这种错误靠 validate() 检查不出来，因为它本身已经不在网格里了。

\n","createdAt":"2024-11-18 12:15:29.873822","updatedAt":"2024-11-18 12:15:29.873822","replyToPostNumber":null,"replyCount":0,"likeCount":0,"wordCount":118,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":3740,"username":"Lskyi","name":null,"avatarUrl":null,"admin":false,"moderator":false,"signatureRaw":null,"signatureCooked":null}},{"id":43375,"postNumber":3,"raw":"```\nfor(Edge* e = edges.head; e != nullptr; e = e->next_node)\n {\n Halfedge* h = e->halfedge;\n Vertex* v1 = h->from;\n Vertex* v2 = h->inv->from;\n Vertex* v3 = h->prev->from;\n Vertex* v4 = h->inv->prev->from;\n size_t d_Per = std::abs(static_cast(v1->degree()-6)) + std::abs(static_cast(v2->degree()-6)) + \n std::abs(static_cast(v3->degree()-6)) + std::abs(static_cast(v4->degree()-6));\n size_t d_Aft = std::abs(static_cast(v1->degree()-7)) + std::abs(static_cast(v2->degree()-5)) + \n std::abs(static_cast(v3->degree()-7)) + std::abs(static_cast(v4->degree()-5));\n if(d_Per > d_Aft)\n {\n flip_edge(e);\n printf(\"Flip successful: %zu\\n\", e->id);\n }\n }\n```\n这是我的边翻转的操作，为什么我翻转边也会卡死，没有理解，我前面的做法是定义了两个 set 类，分别存放要坍缩和分裂的，考虑到一次坍缩少三条边，我坍缩这么来写的：\n```\nfor(Edge* e : selectedCollapseEdges)\n {\n printf(\"Attempting to collapse edge: %zu\\n\", e->id);\n if(selectedCollapseEdges.find(e->halfedge->next->edge) != selectedCollapseEdges.end())\n {\n selectedCollapseEdges.erase(e->halfedge->next->edge);\n }\n if(selectedCollapseEdges.find(e->halfedge->inv->next->edge) != selectedCollapseEdges.end())\n {\n selectedCollapseEdges.erase(e->halfedge->inv->next->edge);\n } \n collapse_edge(e);\n \n printf(\"Collapse successful: %zu\\n\", e->id);\n }\n```\n这么写感觉怪怪的但是能运行过这一段\n![QQ 图片 20241119214110|690x258, 75%](/uploads/image/09/79/09799b295d7aa123e7382c6f2582c4c0a5974b415e8c05a35e7d2f16ed739315.avif)\n这个是我翻转卡死的终端，我不知道是什么原因。 :weary: :tired: :weary: :tired:","cooked":"

for(Edge* e = edges.head; e != nullptr; e = e->next_node)\n        {\n            Halfedge* h = e->halfedge;\n            Vertex* v1 = h->from;\n            Vertex* v2 = h->inv->from;\n            Vertex* v3 = h->prev->from;\n            Vertex* v4 = h->inv->prev->from;\n            size_t d_Per = std::abs(static_cast<long>(v1->degree()-6)) + std::abs(static_cast<long>(v2->degree()-6)) + \n                           std::abs(static_cast<long>(v3->degree()-6)) + std::abs(static_cast<long>(v4->degree()-6));\n            size_t d_Aft = std::abs(static_cast<long>(v1->degree()-7)) + std::abs(static_cast<long>(v2->degree()-5)) + \n                           std::abs(static_cast<long>(v3->degree()-7)) + std::abs(static_cast<long>(v4->degree()-5));\n            if(d_Per > d_Aft)\n            {\n                flip_edge(e);\n                printf(\"Flip successful: %zu\\n\", e->id);\n            }\n        }\n

这是我的边翻转的操作，为什么我翻转边也会卡死，没有理解，我前面的做法是定义了两个 set 类，分别存放要坍缩和分裂的，考虑到一次坍缩少三条边，我坍缩这么来写的：

for(Edge* e : selectedCollapseEdges)\n        {\n                printf(\"Attempting to collapse edge: %zu\\n\", e->id);\n                if(selectedCollapseEdges.find(e->halfedge->next->edge) != selectedCollapseEdges.end())\n                {\n                    selectedCollapseEdges.erase(e->halfedge->next->edge);\n                }\n                if(selectedCollapseEdges.find(e->halfedge->inv->next->edge) != selectedCollapseEdges.end())\n                {\n                    selectedCollapseEdges.erase(e->halfedge->inv->next->edge);\n                }                \n                    collapse_edge(e);\n                    \n                printf(\"Collapse successful: %zu\\n\", e->id);\n        }\n

这么写感觉怪怪的但是能运行过这一段
\n $\"QQ$
\n这个是我翻转卡死的终端，我不知道是什么原因。 😩 😫 😩 😫

\n","createdAt":"2024-11-19 13:42:12.85742","updatedAt":"2024-11-19 13:42:12.85742","replyToPostNumber":null,"replyCount":0,"likeCount":0,"wordCount":219,"liked":false,"bookmarked":false,"polls":[],"reactions":[],"wiki":false,"version":1,"publicVersion":1,"deletedAt":null,"isAnonymous":false,"user":{"id":6145,"username":"SunXueHao","name":"rss","avatarUrl":null,"admin":false,"moderator":false,"signatureRaw":null,"signatureCooked":null}}],"hasMore":false,"lastReadPostNumber":1,"hasUrlPostNumber":false}