# patch

Creates 2D or 3D patches in an axis.

## Syntax

h = patch(x, y, c)

h = patch(x, y, z, c)

h = patch('vertices', vertices_matrix, 'faces', faces_matrix)

h = patch(hAxes, ...)

## Inputs

x, y, z
Coordinates of patch vertices.
Type: double | integer
Dimension: vector | matrix
c
Patch color.
Type: char
vertices_matrix
An Mx2 or Mx3 matrix that contains the coordinates of the patch vertices. M is the number of vertices.
Type: double | integer
Dimension: matrix
faces_matrix
An MxN matrix that contains the indices of the vertices of each patch. M is the number of patches and N is the number of vertices of each patch. NaN may be used if not all polygons have the same number of vertices (see the Examples section).
Type: double | integer
Dimension: matrix
hAxes
Axis handle.
Type: double
Dimension: scalar

## Outputs

h
Handle of the patch graphics object.

## Examples

2D patch plot example:
clf;
t1 = (1/16:1/8:1) * 2*pi;
t2 = ((1/16:1/8:1) + 1/32) * 2*pi;
x = tan (t1) - 0.8;
y = sin (t1);
h = patch (x',y','r')
2D patch plot defined by vertices and faces matrices examples:
x = [0 0.25 0.5 1 1 0.5 0.25 0 -0.5 -0.5]';
y = [0 0 0 0.5 1 1.5 1.5 1.5 1 0.5]';
verts = [x, y];

figure(1);
% Create one patch which constinst of 10 vertices
faces = [1:10];
h = patch('vertices',verts,'faces',faces);

figure(2);
% Create two patches each one consisting of 4 vertices
faces = [3 4 5 6; 8 9 10 1];
h = patch('vertices',verts,'faces',faces);

figure(3);
% Create two patches, the first patch consists of 6 vertices,
% the second patch consists of 4 vertices
faces = [2 3 4 5 6 7; 8 9 10 1 NaN NaN];
h = patch('vertices',verts,'faces',faces);
Example of 3D patch plot. Patch faces are triangles:
clf;
x = [0 1 1 0; 1 1 0 0; 0.5 0.5 0.5 0.5];
y = [0 0 1 1; 0 1 1 0; 0.5 0.5 0.5 0.5];
z = [0 0 0 0; 0 0 0 0; 1 1 1 1];
h = patch(x,y,z,'r');
Example of 3D patch plot. Patch faces are quads:
clf;
x = [0 1 1 0; 1 1 0 0; 1 1 0 0; 0 1 1 0];
y = [0 0 1 1; 0 1 1 0; 0 1 1 0; 0 0 1 1];
z = [0 0 0 0; 0 0 0 0; 1 1 1 1; 1 1 1 1];
h = patch(x,y,z,'r');
Example of 3D patch plot. Patch faces are polygons, triangulation is performed:
clf;
x = [0.5 0; 1.5 0; 2 0; 1.5, 0; 0.5 0; 0 0];
y = [0 0; 0 0.5; 0 1; 0 1.5; 0 1; 0 0.5];
z = [0 0.5; 0 0; 0.5 0; 1 0.5; 1 1; 0.5 1];
h = patch(x,y,z,'r');
Example of 3D patch plot defined by vertices and faces matrices:
clf;
verts = [0 2.5 0; 1 1.5 0; 1.5 1 0;   2 0.5 0; 2.5 0, 0.5; 2 0.5 1;
1.5, 1 1; 1 1.5 0.5; 1 1.5 1; 0 2.5 1; 0.5 2 0.5];
faces = [1 2 11 NaN NaN NaN; 9 10 11 NaN NaN NaN; 3 4 5 6 7 8];
h = patch('vertices',verts,'faces',faces);

The color of a 3D patch can be defined as:

• one color for all faces of the patch
• a scalar per vertex mapped to the colormap
• a scalar per face mapped to the colormap
• a color per face
Set one color to all faces of the 3D patch:
verts = [0 2.5 0; 1 1.5 0; 1.5 1 0;   2 0.5 0; 2.5 0, 0.5; 2 0.5 1;
1.5, 1 1; 1 1.5 0.5; 1 1.5 1; 0 2.5 1; 0.5 2 0.5];
faces = [1 2 11 NaN NaN NaN; 9 10 11 NaN NaN NaN; 3 4 5 6 7 8];

figure;
h = patch('vertices',verts,'faces',faces);
set(h,'facecolor',[250 0 250]]);

Set a scalar per vertex:
verts = [0 2.5 0; 1 1.5 0; 1.5 1 0;   2 0.5 0; 2.5 0, 0.5; 2 0.5 1;
1.5, 1 1; 1 1.5 0.5; 1 1.5 1; 0 2.5 1; 0.5 2 0.5];
faces = [1 2 11 NaN NaN NaN; 9 10 11 NaN NaN NaN; 3 4 5 6 7 8];

figure;
h = patch('vertices',verts,'faces',faces);
% facecolor = 'interp', the color of each face is defined by interpolating
% the cdata values of its vertices.
% if 'cdata' is not given then the 'zdata' values will be used.
set(h,'facecolor', 'interp');

figure;
h = patch('vertices',verts,'faces',faces);
% set a scalar value for each vertex
cdata = [0 1 2 NaN NaN NaN; 3 4 5  NaN NaN NaN; 6 7 8 9 10 11]';
set(h,'cdata', cdata)
set(h,'facecolor', 'interp')

figure;
h = patch('vertices',verts,'faces',faces);
% set a scalar value for each vertex
set(h,'cdata', cdata)
% facecolor = 'flat', the color of each face is defined by the cdata
% value of its first vertex.
set(h,'facecolor', 'flat')
Set color per face:
x = [0 1 1 0; 1 1 0 0; 1 1 0 0; 0 1 1 0];
y = [0 0 1 1; 0 1 1 0; 0 1 1 0; 0 0 1 1];
z = [0 0 0 0; 0 0 0 0; 1 1 1 1; 1 1 1 1];

figure;
h = patch(x,y,z,'r');
% set a scalar value for each face
set(h,'cdata',[0 9 6 4])
set(h,'facecolor', 'flat')
set(gca,'contourtype','discrete')

figure;
h = patch(x, y, z, 'r');
% set an rgb color for each face
cdata =[];
cdata(:,:,1) = [255 0 0 255]; % red component
cdata(:,:,2) = [0 0 255 0]; % green component
cdata(:,:,3) = [255 255 0 0]; % blue component
set(h,'cdata',cdata)
set(h,'facecolor', 'flat')