Create color filled cirlcle to dxf file

Hi, I'm trying to develop a script to create a colour filled circle to a DXF file. For example, I'm thinking of a circle with a known radius and with different values for coordinates (X and Y) and a Z value. This Z value should be related to a colour (for example, a colormap). What should I do?

One option could be:

fullname='test_1.dxf';
fid=fopen(fullname,'w');
fprintf(fid,'CIRCLE\n');
fprintf(fid,'0,0\n');      %Coordinates for center
fprintf(fid,'1\n');        %Radius
fclose(fid);

But it doesn't work. Moreover is missing the filled colour depending on a Z value. What should I do?

Answer 1

[Rupesh]

Hi Eddie,

To create a color-filled circle in a DXF file based on a Z value in MATLAB, you will need to use a combination of MATLAB functions to generate the circle's geometry and map the Z value to a specific color. MATLAB does not directly support writing to DXF with color fill properties via its built-in functions, but you can manually construct the DXF commands in a text file. First, determine the color based on the Z value by using MATLAB's colormap functions (e.g., jet, hsv). Then, manually write the DXF commands to define a HATCH entity for a solid fill and a LWPOLYLINE or CIRCLE for the boundary, setting the color according to the ACI (AutoCAD Color Index) that corresponds to your Z value.

% Define parameters
fullname = 'test_1.dxf';
center = [0, 0]; % Circle center
radius = 1; % Circle radius
zValue = 0.5; % Example Z value
colors = jet(256); % Using the jet colormap, 256 colors
colorIndex = round(zValue * 255) + 1; % Map zValue to color index, simple linear mapping

% Open file
fid = fopen(fullname, 'w');

% Write DXF header and tables (not detailed here)
fprintf(fid, '0\nSECTION\n2\nTABLES\n0\nENDSEC\n');

% Write entities section with a HATCH entity for the color fill
fprintf(fid, '0\nSECTION\n2\nENTITIES\n');
% Example of writing a HATCH entity, simplified
fprintf(fid, '0\nHATCH\n'); % Start hatch entity
% ... HATCH definition details here ...
fprintf(fid, '0\nENDSEC\n');

% Close file
fclose(fid);

You can also refer to below matlab answer for more information regarding animation in files.

How can I draw a filled circle? - MATLAB Answers - MATLAB Central (mathworks.com)

Hope this helps!

Thanks