Merge pull request zeux#890 from zeux/gltf-lines

gltfpack: Implement support for lines in OBJ files

Author: zeux

extern/fast_obj.h

@@ -137,6 +137,7 @@ typedef struct
     unsigned int                face_count;
     unsigned int*               face_vertices;
     unsigned int*               face_materials;
+    unsigned char*              face_lines;
 
     /* Index data: one element for each face vertex */
     unsigned int                index_count;
@@ -734,7 +735,7 @@ const char* parse_normal(fastObjData* data, const char* ptr)
 
 
 static
-const char* parse_face(fastObjData* data, const char* ptr)
+const char* parse_face(fastObjData* data, const char* ptr, unsigned char line)
 {
     unsigned int count;
     fastObjIndex vn;
@@ -796,6 +797,16 @@ const char* parse_face(fastObjData* data, const char* ptr)
     array_push(data->mesh->face_vertices, count);
     array_push(data->mesh->face_materials, data->material);
 
+    if (line || data->mesh->face_lines)
+    {
+        /* when line info exists, ensure it uses aligned indexing with other face data */
+        size_t skipped = array_size(data->mesh->face_vertices) - array_size(data->mesh->face_lines);
+        while (--skipped > 0)
+            array_push(data->mesh->face_lines, 0);
+
+        array_push(data->mesh->face_lines, line);
+    }
+
     data->group.face_count++;
     data->object.face_count++;
 
@@ -1295,7 +1306,22 @@ void parse_buffer(fastObjData* data, const char* ptr, const char* end, const fas
             {
             case ' ':
             case '\t':
-                p = parse_face(data, p);
+                p = parse_face(data, p, 0);
+                break;
+
+            default:
+                p--; /* roll p++ back in case *p was a newline */
+            }
+            break;
+
+        case 'l':
+            p++;
+
+            switch (*p++)
+            {
+            case ' ':
+            case '\t':
+                p = parse_face(data, p, 1);
                 break;
 
             default:
@@ -1398,6 +1424,7 @@ void fast_obj_destroy(fastObjMesh* m)
     array_clean(m->colors);
     array_clean(m->face_vertices);
     array_clean(m->face_materials);
+    array_clean(m->face_lines);
     array_clean(m->indices);
     array_clean(m->objects);
     array_clean(m->groups);
@@ -1454,6 +1481,7 @@ fastObjMesh* fast_obj_read_with_callbacks(const char* path, const fastObjCallbac
     m->colors         = 0;
     m->face_vertices  = 0;
     m->face_materials = 0;
+    m->face_lines     = 0;
     m->indices        = 0;
     m->materials      = 0;
     m->textures       = 0;

gltf/parseobj.cpp

@@ -216,17 +216,33 @@ static void parseMeshObj(fastObjMesh* obj, unsigned int face_offset, unsigned in
 	{
 		unsigned int face_vertices = obj->face_vertices[face_offset + fi];
 
-		for (unsigned int vi = 2; vi < face_vertices; ++vi)
+		if (mesh.type == cgltf_primitive_type_lines)
 		{
-			size_t to = index_offset + (vi - 2) * 3;
+			for (unsigned int vi = 1; vi < face_vertices; ++vi)
+			{
+				size_t to = index_offset + (vi - 1) * 2;
 
-			mesh.indices[to + 0] = remap[vertex_offset];
-			mesh.indices[to + 1] = remap[vertex_offset + vi - 1];
-			mesh.indices[to + 2] = remap[vertex_offset + vi];
+				mesh.indices[to + 0] = remap[vertex_offset + vi - 1];
+				mesh.indices[to + 1] = remap[vertex_offset + vi];
+			}
+
+			vertex_offset += face_vertices;
+			index_offset += (face_vertices - 1) * 2;
 		}
+		else
+		{
+			for (unsigned int vi = 2; vi < face_vertices; ++vi)
+			{
+				size_t to = index_offset + (vi - 2) * 3;
 
-		vertex_offset += face_vertices;
-		index_offset += (face_vertices - 2) * 3;
+				mesh.indices[to + 0] = remap[vertex_offset];
+				mesh.indices[to + 1] = remap[vertex_offset + vi - 1];
+				mesh.indices[to + 2] = remap[vertex_offset + vi];
+			}
+
+			vertex_offset += face_vertices;
+			index_offset += (face_vertices - 2) * 3;
+		}
 	}
 
 	assert(vertex_offset == face_vertex_count);
@@ -241,16 +257,17 @@ static void parseMeshGroupObj(fastObjMesh* obj, const fastObjGroup& og, cgltf_da
 	for (unsigned int face_offset = og.face_offset; face_offset < face_end_offset;)
 	{
 		unsigned int mi = obj->face_materials[face_offset];
+		unsigned char isl = obj->face_lines ? obj->face_lines[face_offset] : 0;
 
 		unsigned int face_count = 0;
 		unsigned int face_vertex_count = 0;
 		unsigned int index_count = 0;
 
-		for (unsigned int fj = face_offset; fj < face_end_offset && obj->face_materials[fj] == mi; ++fj)
+		for (unsigned int fj = face_offset; fj < face_end_offset && obj->face_materials[fj] == mi && (!obj->face_lines || obj->face_lines[fj] == isl); ++fj)
 		{
 			face_count += 1;
 			face_vertex_count += obj->face_vertices[fj];
-			index_count += (obj->face_vertices[fj] - 2) * 3;
+			index_count += isl ? (obj->face_vertices[fj] - 1) * 2 : (obj->face_vertices[fj] - 2) * 3;
 		}
 
 		meshes.push_back(Mesh());
@@ -262,7 +279,7 @@ static void parseMeshGroupObj(fastObjMesh* obj, const fastObjGroup& og, cgltf_da
 			mesh.material = &data->materials[mi];
 		}
 
-		mesh.type = cgltf_primitive_type_triangles;
+		mesh.type = isl ? cgltf_primitive_type_lines : cgltf_primitive_type_triangles;
 		mesh.targets = 0;
 
 		if (node)