preserve meta when converting

Author: SimonDanisch

src/geometry_primitives.jl

@@ -6,6 +6,11 @@ function widths(x::AbstractRange)
     return maxi - mini
 end
 
+# GeometryPrimitive's don't have attributes per se
+function attributes(nometa::GeometryPrimitive)
+    return Dict{Symbol, Any}()
+end
+
 ##
 # conversion & decompose
 

src/meshes.jl

@@ -110,25 +110,32 @@ function mesh(primitive::Meshable;
         # triangulation.jl
         faces = decompose(facetype, positions)
     end
-    attributes = Dict{Symbol, Any}()
+
+    # We want to preserve any existing attributes!
+    attrs = attributes(primitive)
+    # Make sure this doesn't contain position, we'll add position explicitely via meta!
+    delete!(attrs, :position)
 
     if uv !== nothing
-        attributes[:uv] = decompose(UV(uv), primitive)
+        # this may overwrite an existing :uv, but will only create a copy
+        # if it has a different eltype, otherwise it should replace it
+        # with exactly the same instance - which is what we want here
+        attrs[:uv] = decompose(UV(uv), primitive)
     end
 
     if normaltype !== nothing
         primitive_normals = normals(primitive)
         if primitive_normals !== nothing
-            attributes[:normals] = decompose(normaltype, primitive_normals)
+            attrs[:normals] = decompose(normaltype, primitive_normals)
         else
             # Normals not implemented for primitive, so we calculate them!
             n = normals(positions, faces)
             if n !== nothing # ok jeez, this is a 2d mesh which cant have normals
-                attributes[:normals] = n
+                attrs[:normals] = n
             end
         end
     end
-    return Mesh(meta(positions; attributes...), faces)
+    return Mesh(meta(positions; attrs...), faces)
 end
 
 """

test/runtests.jl

@@ -323,6 +323,27 @@ end
     include("geometrytypes.jl")
 end
 
+@testset "convert mesh + meta" begin
+    m = uv_normal_mesh(FRect3D(Vec3f0(-1), Vec3f0(1, 2, 3)))
+    m_normal = normal_mesh(m)
+    # make sure we don't loose the uv
+    @test hasproperty(m_normal, :uv)
+    @test m == m_normal
+    # Make sure we don't create any copies
+    @test m.position === m_normal.position
+    @test m.normals === m_normal.normals
+    @test m.uv === m_normal.uv
+
+    m = GeometryBasics.mesh(FRect3D(Vec3f0(-1), Vec3f0(1, 2, 3));
+                            uv=Vec2{Float64}, normaltype=Vec3{Float64}, pointtype=Point3{Float64})
+    m_normal = normal_mesh(m)
+    @test hasproperty(m_normal, :uv)
+    @test m.position !== m_normal.position
+    @test m.normals !== m_normal.normals
+    # uv stays untouched, since we don't specify the element type in normalmesh
+    @test m.uv === m_normal.uv
+end
+
 @testset "modifying meta" begin
     xx = rand(10)
     points = rand(Point3f0, 10)