hasufell/half-edge
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Try to fix normals for open edges

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Probably still not correct, depending on the complexity
of the object.
This commit is contained in:
hasufell 2014-05-15 18:52:28 +02:00
parent 3687646974
commit aaa485f072
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GPG Key ID: 220CD1C5BDEED020
2 changed files with 39 additions and 6 deletions
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32
src/half_edge.c
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@ -99,7 +99,7 @@ static bool get_all_emanating_edges(HE_vert const * const vert,
rc++;
}
} while (edge != vert->edge);
} while (edge && edge != vert->edge);
/* set out-pointers */
*edge_array_out = edge_array;
@ -370,7 +370,8 @@ HE_obj *parse_obj(char const * const obj_string)
faces = (HE_face*) malloc(sizeof(HE_face) * fc);
CHECK_PTR_VAL(faces);
edges = (HE_edge*) malloc(sizeof(HE_edge) * ec);
/* hold enough space for possible dummy edges */
edges = (HE_edge*) malloc(sizeof(HE_edge) * ec * 2);
CHECK_PTR_VAL(edges);
ec = 0;
@ -429,6 +430,7 @@ HE_obj *parse_obj(char const * const obj_string)
/* find pairs */
for (uint32_t i = 0; i < ec; i++) { /* for all edges */
uint32_t eac = edges[i].vert->eac;
bool pair_found = false;
for (uint32_t j = 0; j < eac; j++) { /* for all potential pairs */
if (edges[i].vert->edge_array[j] &&
@ -436,11 +438,36 @@ HE_obj *parse_obj(char const * const obj_string)
edges[i].vert->edge_array[j]->vert)) {
edges[i].pair = edges[i].vert->edge_array[j];
edges[i].vert->edge_array[j] = NULL;
/* this is a trick to make sure the
* edge member of HE_vert is never
* a border-edge (unless there are only
* border edges), otherwise
* get_all_emanating_edges() would break
* for vertices that are at the edge
* of an open object */
edges[i].vert->edge = &(edges[i]);
pair_found = true;
break;
}
}
if (!pair_found) { /* we have a border edge */
/* add dummy edge, so get_all_emanating_edges()
* does not break */
edges[ec + i].face = NULL;
edges[ec + i].next = NULL;
edges[ec + i].pair = &(edges[i]);
edges[ec + i].vert = edges[i].next->vert;
edges[i].pair = &(edges[ec + i]);
}
}
/* don't need the edge array anymore */
for (uint32_t i = 0; i < vc; i++)
free(vertices[i].edge_array);
obj = (HE_obj*) malloc(sizeof(HE_obj));
CHECK_PTR_VAL(obj);
@ -472,7 +499,6 @@ void delete_object(HE_obj *obj)
for (uint32_t i = 0; i < obj->vc; i++) {
free(obj->vertices[i].vec);
free(obj->vertices[i].col);
free(obj->vertices[i].edge_array);
}
free(obj->edges);
free(obj->vertices);

13
src/half_edge.h
View File

@ -118,6 +118,8 @@ struct HE_edge {
HE_vert *vert;
/**
* Oppositely oriented adjacent half-edge.
* Border edges have a dummy pair which have "face"
* and "next" set to NULL.
*/
HE_edge *pair;
/**
@ -143,14 +145,19 @@ struct HE_vert {
/**
* One of the half-edges emanating from the vertex.
* It is made sure that this is never a border edge,
* unless there are only border edges.
*/
HE_edge *edge;
/**
* Acceleration structure which saves all
* edges that point TO this vertex. It is used
* Acceleration structure which saves all potential
* pair edges that point TO this vertex. It is used
* for finding the pairs when assembling
* the HE_edge struct.
* the HE_edge struct. Note that this does not reliably
* save all border edges (which is a non-issue for the
* specific purpose of this struct since border-edges
* don't qualify for pairs anyway).
*/
HE_edge **edge_array;