matlab - MeshGrid for Triangle Elements -

i want build contourf plot of aspect in plate. plate divided in triangle elements, have coordinates (x,y) of each knot of triangle.

so, how can make meshgrid knots can make contourf plot?? have coordinates of , have value of function z in each knot. (i'm beginner in matlab, sorry "basic" question)

if goal visualise triangles there way that's simpler , more robust (see end of post).

if need generate contours need interpolate triangular mesh on grid. can use scatteredinterpolant class (documentation here). takes x , y arguments or triangular vertices (knots), z values each 1 , creates 'function' can use evaluate other points. create grid, interpolate triangular mesh on grid , can use results countour plot.

the inputs scatteredinterpolanthave linear column vectors, need reshape them using the(:)`notation.

so let's assume have triangular data this

x = [1 4; 8 9]; y = [2 3; 4 5]; z = [0.3 42; 16 8]; 

you work out upper , lower limits of range first

xlimits = minmax(x(:)); ylimits = minmax(y(:)); 

where (:) notation serves line elements of x in single column.

then can create meshgrid spans range. need decide how fine grid should be.

spacing = 1; xqlinear = xlimits(1):spacing:xlimits(2); yqlinear = ylimits(1):spacing:ylimits(2); 

where linspace makes vector of values starting @ first 1 (xlimits(1)) , ending @ third 1 (xlimits(2)) , separated spacing. experiment , @ results, you'll see how works.

these 2 vectors specify grid positions in each dimension. make actual meshgrid-style grid call meshgrid on them

[xq, yq] = meshgrid(xqlinear, yqlinear); 

this produce 2 matrices of points. xq holds x-coordinates of every points in grid, arranged in same grid. yq holds y-coordinates. 2 need go together. again experiment , @ results, you'll see how works.

then can put them interpolation:

f = scatteredinterpolant(x(:), y(:), z(:)); zq = f(xq, yq); 

to interpolated values zq @ each of grid points. can send data contourf

contourf(xq, yq, zq); 

if contour blocky need make spacing value smaller, create more points in interpolant. if have lots of data might cause memory issues, aware of that.

if goal view triangular mesh might find trimesh want or, depending on how data represented, scatter. these both produce 3d plots wireframes or point clouds though if need contours interpolation way go.