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CalcNormals.m
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CalcNormals.m
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function [vertNormals, faceNormals] = CalcNormals(verts, faces)
faceNormals = CalcFaceNormals(verts, faces);
vertNormals = CalcVertNormals(verts, faces, faceNormals);
[vertNormals, faceNormals] = NormalizeNormals(vertNormals, faceNormals);
end
function faceNormals = CalcFaceNormals(verts, faces)
faceNormals = zeros(size(faces, 1), 3);
for i=1:size(faces, 1)
a = verts(faces(i, 1), :);
b = verts(faces(i, 2), :);
c = verts(faces(i, 3), :);
ca = c - a;
ba = b - a;
n = cross(ba, ca);
faceNormals(i, :) = n;
end
end
function vertNormals = CalcVertNormals(verts, faces, faceNormals)
vertNormals = zeros(size(verts, 1), 3);
for i=1:size(verts, 1)
[rows_with_vert, ~] = find(faces == i);
rows_with_vert = unique(rows_with_vert); % Make sure to filter out duplicates. Might happen if a triangle has duplicate vertices. Shouldn't happen, but you never know.
n = sum(faceNormals(rows_with_vert, :), 1);
vertNormals(i, :) = n;
end
end
function [vertNormals, faceNormals] = NormalizeNormals(vertNormals, faceNormals)
for i=1:size(faceNormals, 1)
faceNormals(i, :) = faceNormals(i, :) / sqrt(sum(faceNormals(i, :) .^ 2));
end
for i=1:size(vertNormals, 1)
vertNormals(i, :) = vertNormals(i, :) / sqrt(sum(vertNormals(i, :) .^ 2));
end
end