How can I plot a 3D-plane in Matlab?

Question

I would like to plot a plane using a vector that I calculated from 3 points where:

pointA = [0,0,0];
pointB = [-10,-20,10];
pointC = [10,20,10];

plane1 = cr         


        

Answer 1

You have already calculated the normal vector. Now you should decide what are the limits of your plane in x and z and create a rectangular patch.

An explanation : Each plane can be characterized by its normal vector (A,B,C) and another coefficient D. The equation of the plane is AX+BY+CZ+D=0. Cross product between two differences between points, cross(P3-P1,P2-P1) allows finding (A,B,C). In order to find D, simply put any point into the equation mentioned above:

   D = -Ax-By-Cz;

Once you have the equation of the plane, you can take 4 points that lie on this plane, and draw the patch between them.

normal = cross(pointA-pointB, pointA-pointC); %# Calculate plane normal
%# Transform points to x,y,z
x = [pointA(1) pointB(1) pointC(1)];  
y = [pointA(2) pointB(2) pointC(2)];
z = [pointA(3) pointB(3) pointC(3)];

%Find all coefficients of plane equation    
A = normal(1); B = normal(2); C = normal(3);
D = -dot(normal,pointA);
%Decide on a suitable showing range
xLim = [min(x) max(x)];
zLim = [min(z) max(z)];
[X,Z] = meshgrid(xLim,zLim);
Y = (A * X + C * Z + D)/ (-B);
reOrder = [1 2  4 3];
figure();patch(X(reOrder),Y(reOrder),Z(reOrder),'b');
grid on;
alpha(0.3);