Error using horzcat Dimensions of arrays being concatenated are not consistent.

n=20;
xleft = -100;
xright = 100;
yfront = 0;
yback = 200;
step = 1;
[x,y] = meshgrid(xleft:step:xright,yfront:step:yback);
faces = delaunay(x,y);

a=0;
for i=xleft:step:yback
    a = a+1;
    b = 0;
    for j=yfront:step:yback
        b = b+1;
        if i>-10 && i<50 &&i>30 &&j<50
            z(a,b) = 15;
        else
            z(a,b) = 0;
        end
    end
end
vertices = [x(:) y(:) z(:)];
orig = [0 0 20];
%dir = [-10 20 -2];
vert1 = vertices(faces(:,1),:);
vert2 = vertices(faces(:,2),:);
vert3 = vertices(faces(:,3),:);

[KSSV]

Check the sizes of x, y, z..they are not same so error.

NOTE: Don't attch your code as image snippet. You should copy paste here.

[YINGNAN SUN]

n=20;
xleft = -100;
xright = 100;
yfront = 0;
yback = 200;
step = 1;
[x,y] = meshgrid(xleft:step:xright,yfront:step:yback);
faces = delaunay(x,y);

a=0;
for i=xleft:step:yback
    a = a+1;
    b = 0;
    for j=yfront:step:yback
        b = b+1;
        if i>-10 && i<50 &&i>30 &&j<50
            z(a,b) = 30;
        else
            z(a,b) = 0;
        end
    end
end
vertices = [x(:) y(:) z(:)];
orig = [0 0 20];
%dir = [-10 20 -2];
vert1 = vertices(faces(:,1),:);
vert2 = vertices(faces(:,2),:);
vert3 = vertices(faces(:,3),:);

am not sure what's size of x,y,z.

just follow teacher's code, is same but not work foe me.

[KSSV]

The dimensions of x, y, z are 201*201, 201*201, 301*201 respectively.....so you cannot join them..

[YINGNAN SUN]

yep found that, but dont know how to fix that

Answer 1

[Walter Roberson]

for i=xleft:step:yback

That is dubious, especially considering

 for j=yfront:step:yback

what happened to xright ?

[x,y] = meshgrid(xleft:step:xright,yfront:step:yback);

for j=yfront:step:yback

Technically speaking, it is not guaranteed that the colon operator in a for loop will give exactly the same values as the colon operator that you used in your meshgrid call. You should do something like

xvec = xleft:step:xright;
yvec = yfront:step:yback;
[x, y] = meshgrid(xvec, yvec);

and later

for i=xvec
    for j = yvec

Your double for loop can be optimized away as

a = zeros(size(x));
a( x>-10 & x<50 & y>30 & y<50) = 30;

with no loop at all.