triangle_uv.m

hodge decomposition for 2D vector fields.

function UV=triangle_uv(triangle,mesh,start_x,start_y,delta_x,delta_y,uu,vv) 
%% generate the Average Vector Table 
%% triangle: the Grid Table 
%% mesh: the Node Table 
%% start_x: start coordinate in horizontal direction 
%% start_y: start coordinate in vertical direction 
%% delta_x: step in horizontal direction 
%% delta_y: step in vertical direction 
%% uu: horizontal component of the input motion field 
%% vv: vertical component of the input motion field 
%% UV: The resulted Average Vector Table 
M=size(triangle,1); 
UV=zeros(M,2);  
for i=1:M 
loc1=mesh(triangle(i,1),:); 
loc2=mesh(triangle(i,2),:); 
loc3=mesh(triangle(i,3),:); 
ind_y1=floor((loc1(1)-start_y)/delta_y)+1; 
ind_x1=floor((loc1(2)-start_x)/delta_x)+1; 
ind_y2=floor((loc2(1)-start_y)/delta_y)+1; 
ind_x2=floor((loc2(2)-start_x)/delta_x)+1; 
ind_y3=floor((loc3(1)-start_y)/delta_y)+1; 
ind_x3=floor((loc3(2)-start_x)/delta_x)+1; 
UV(i,1)=(uu(ind_y1,ind_x1)+uu(ind_y2,ind_x2)+uu(ind_y3,ind_x3))/3; 
UV(i,2)=(vv(ind_y1,ind_x1)+vv(ind_y2,ind_x2)+vv(ind_y3,ind_x3))/3; 
end; 
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