102 lines
2.0 KiB
Odin
102 lines
2.0 KiB
Odin
package halfedge
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Vec3 :: [3]f32
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Vertex :: struct {
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pos: Vec3,
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edge: Edge_Index,
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}
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Face :: struct {
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edge: Edge_Index,
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}
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Vertex_Index :: distinct u16
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Face_Index :: distinct u16
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Edge_Index :: distinct i16
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Half_Edge :: struct {
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origin: Vertex_Index,
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twin: Edge_Index,
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face: Face_Index,
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next: Edge_Index,
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prev: Edge_Index,
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}
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Half_Edge_Mesh :: struct {
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vertices: []Vertex,
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faces: []Face,
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edges: []Half_Edge,
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}
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mesh_from_vertex_index_list :: proc(
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vertices: []Vec3,
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indices: []u16,
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allocator := context.allocator,
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) -> Half_Edge_Mesh {
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mesh: Half_Edge_Mesh
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verts := make([]Vertex, len(vertices), allocator)
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faces := make([]Face, len(indices) / 3, allocator)
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edges := make([]Half_Edge, len(indices), allocator)
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mesh.vertices = verts
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mesh.faces = faces
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mesh.edges = edges
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for pos, i in vertices {
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verts[i].pos = pos
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verts[i].edge = -1
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}
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temp_edges: map[[2]u16]Edge_Index = make_map(map[[2]u16]Edge_Index, context.temp_allocator)
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triangle_num := len(indices) / 3
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for i in 0 ..< triangle_num {
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i1, i2, i3 := indices[i * 3 + 0], indices[i * 3 + 1], indices[i * 3 + 2]
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// v1, v2, v3 := vertices[i1], vertices[i2], vertices[i3]
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e1, e2, e3 := i * 3 + 0, i * 3 + 1, i * 3 + 2
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faces[i].edge = Edge_Index(e1)
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edges[e1] = {
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origin = Vertex_Index(i1),
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twin = -1,
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face = Face_Index(i),
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next = Edge_Index(e2),
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prev = Edge_Index(e3),
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}
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edges[e2] = {
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origin = Vertex_Index(i2),
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twin = -1,
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face = Face_Index(i),
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next = Edge_Index(e3),
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prev = Edge_Index(e1),
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}
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edges[e3] = {
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origin = Vertex_Index(i3),
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twin = -1,
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face = Face_Index(i),
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next = Edge_Index(e1),
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prev = Edge_Index(e2),
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}
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edge_stable_indices := [][2]u16 {
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{min(i1, i2), max(i1, i2)},
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{min(i2, i3), max(i2, i3)},
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{min(i3, i1), max(i3, i1)},
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}
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for stable_idx, j in edge_stable_indices {
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twin, ok := temp_edges[stable_idx]
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ei := i * 3 + j
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if ok {
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edges[ei].twin = twin
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edges[twin].twin = Edge_Index(ei)
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} else {
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temp_edges[stable_idx] = Edge_Index(ei)
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}
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}
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}
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return mesh
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}
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