Apply a color variation to a triangular face

Hi! I have this code. I would like to color the face of the triangle taking into account the RGB colors present on the three nodes.

node_1 = [-46.924, 11.0584, -59.8431];
node_2 = [-45.9522, 13.4294, -59.5705];
node_3 = [-46.4695, 9.8787, -57.7669];
nodes = [node_1; node_2; node_3];
face = [1,2,3];
    
figure
plot3(node_1(:,1),node_1(:,2),node_1(:,3),'.','Color',[176/255,255/255,0/255],'Markersize',20)
hold on
plot3(node_2(:,1),node_2(:,2),node_2(:,3),'.','Color',[0/255,255/255,155/255],'Markersize',20)
plot3(node_3(:,1),node_3(:,2),node_3(:,3),'.','Color',[0/255,199/255,255/255],'Markersize',20)
trimesh(face(:,:),nodes(:,1),nodes(:,2),nodes(:,3),'EdgeColor',[210/255, 210/255, 210/255],'Linewidth',1,'Facecolor','w')
hold off
grid off
view([20,130,40])

Answer 1

[Walter Roberson]

Assign the result of trimesh() to a variable. The result will be a patch object.

You can then set the patch properties. In particular, look at https://www.mathworks.com/help/matlab/ref/matlab.graphics.primitive.patch-properties.html#buduav0-1-FaceVertexCData FaceVertexCData along with 'FaceColor', 'interp' . Done right you can assign a color to each vertex, and then the face color will be a progressive interpolation between the colors of the vertices.

[Alberto Acri]

Thank you for your reply. Is there any code available to do this? Or do you know how it could be done?

[Walter Roberson]

node_1 = [-46.924, 11.0584, -59.8431];
node_2 = [-45.9522, 13.4294, -59.5705];
node_3 = [-46.4695, 9.8787, -57.7669];
nodes = [node_1; node_2; node_3];
face = [1,2,3];

vertex_colors = [1 0 0;
                 0 1 0;
                 0 0 1];

h = trimesh(face(:,:),nodes(:,1),nodes(:,2),nodes(:,3),'EdgeColor',[210/255, 210/255, 210/255],'Linewidth',1,'Facecolor','w')

h = 
  Patch with properties:

    FaceColor: [1 1 1]
    FaceAlpha: 1
    EdgeColor: [0.8235 0.8235 0.8235]
    LineStyle: '-'
        Faces: [1 2 3]
     Vertices: [3×3 double]

  Show all properties

h.FaceVertexCData = vertex_colors;
h.FaceColor = 'interp';
view([20,130,40])

[Alberto Acri]

Thank you for your reply. But I wanted to start with the colors present in the vertices that are mixed in the center of the triangle.

The colors are:

for node 1: [176/255,255/255,0/255]

For node 2: [0/255,255/255,155/255]

for node 3: [0/255,199/255,255/255]

[Walter Roberson]

node_1 = [-46.924, 11.0584, -59.8431];
node_2 = [-45.9522, 13.4294, -59.5705];
node_3 = [-46.4695, 9.8787, -57.7669];
nodes = [node_1; node_2; node_3];
face = [1,2,3];

vertex_colors = [176, 255, 255
                 0,   255, 155
                 0,   199, 255]./255;

h = trimesh(face(:,:),nodes(:,1),nodes(:,2),nodes(:,3),'EdgeColor',[210/255, 210/255, 210/255],'Linewidth',1,'Facecolor','w')

h = 
  Patch with properties:

    FaceColor: [1 1 1]
    FaceAlpha: 1
    EdgeColor: [0.8235 0.8235 0.8235]
    LineStyle: '-'
        Faces: [1 2 3]
     Vertices: [3×3 double]

  Show all properties

h.FaceVertexCData = vertex_colors;
h.FaceColor = 'interp';
view([20,130,40])

[Alberto Acri]

perfect!