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55 lines
1.6 KiB
55 lines
1.6 KiB
2 years ago
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function [new_n,new_Xi,new_P,new_w] = NURBS_Curve_Refine(d,add_Xi,p,n,Xi,P,w)
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% Determine what new_Xi should look like:
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new_Xi = sort([Xi, add_Xi]);
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% Do all the calculation in projective space: That is multiply the control
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% points by their weights:
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for i = 1:d
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P(:,i) = P(:,i).*w;
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end
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P(:,d+1) = w;
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% Knot Interstion:
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% We know what we want our final knot vector to look like, so we'll do knot
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% insertion until our KV matches our KVF.
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for i = 1:length(new_Xi)
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% Check to see if the current knot in KV matches the current knot in
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% KVF. If it does, great, move on to the next knot, if not, calculate
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% new control points and insert KVF(i) into KV(i).
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if new_Xi(i) == Xi(i)
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continue
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else
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% Correct for the algorithm indexing by zero
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ki = i-1;
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% Calculate the new control points
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% Loop through indexes from k-p+1 to k and calculate the new control
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% points
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for j = ki-p+1:ki
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a(j) = (new_Xi(i)-Xi(j))/(Xi(j+p)-Xi(j));
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Q(j,:) = (1-a(j))*P(j-1,:) + a(j)*P(j,:);
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end
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% Move control points below ki-1 down by 1 space to
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% make room for the p new points;
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P(ki+1:length(P)+1,:) = P(ki:length(P),:);
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% Insert the new control points
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P(ki-p+1:ki,:) = Q(ki-p+1:ki,:);
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% move the knots to the right of the knot to be inserted over one
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% index
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Xi(i+1:end+1) = Xi(i:end);
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% Insert the knot to the knot vector.
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Xi(i) = new_Xi(i);
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end
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end
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new_w = P(:,d+1);
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for i = 1:d
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new_P(:,i) = P(:,i)./new_w;
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end
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new_n = size(new_P,1);
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return
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