I wrote this method and surprisingly figured out that the resulting mesh not only has an affine distortion but is still always continuous/seamless – even if it resulted from a projective distortion. That's something I've wanted for long for cases that don't work for projected textures.
Of course the conversion is not lossless, the more subdivided the mesh is, the less noticeable is the difference.
- Code: Select all
def realign_uvs(entities=Sketchup.active_model.selection.to_a)
model = Sketchup.active_model
if Sketchup.version.to_i >= 7
model.start_operation("Repair misaligned UV coordinates", true)
else
model.start_operation("Repair misaligned UV coordinates")
end
@tw = Sketchup.create_texture_writer
side = true # frontside
hash = {} # vertex => [uvs]
faces = entities.find_all{|e| e.is_a?(Sketchup::Face) && (mat = (side)? e.material : e.back_material) && mat.materialType>0}
# 1) Let's collect all uvs at each vertex
faces.each{|f|
uv_helper = f.get_UVHelper(true, true, @tw)
f.vertices.each{|v|
p = v.position
uv = (side)? uv_helper.get_front_UVQ(p) : uv_helper.get_back_UVQ(p)
uv.x /= uv.z; uv.y /= uv.z; uv.z = 1
hash[v] = [] if !hash[v]
hash[v] << uv
}
}
# 2) Find the uv with the least aberration. Alternative: Calculate the average of the uvs at a vertex.
hash.each{|v, array|
#average_uv = array.inject(Geom::Point3d.new([0,0,0])){|sum, uv| sum+uv.to_a}.to_a.collect{|c| c/array.length.to_f}
#hash[v] = average_uv
best_uv = array.min{|uv_a,uv_b|
dist_a = array.inject(0){|dist, uv| d = uv_a.distance(uv); [d,dist].min} # sum of distances from uv_a
dist_b = array.inject(0){|dist, uv| d = uv_b.distance(uv); [d,dist].min} # sum of distances from uv_b
dist_b <=> dist_a}
hash[v] = best_uv
}
# 3) Apply the uvs for each face
faces.each{|f|
pt_array = []
vs = f.vertices[0..3]
vs.each{|v|
pt_array << v.position
pt_array << hash[v]
}
f.position_material(((side)? f.material : f.back_material), pt_array, side)
}
model.commit_operation
end
