How to Generate Perfect Circles for Minecraft Builds in MATLAB

Hello MATLAB Community,

I am currently working on a project related to Minecraft, where I need to create perfect circles as a guide for building structures within the game. Given the blocky nature of Minecraft, creating smooth circles can be challenging. I am looking to utilize MATLAB to generate these circle templates.

My goal is to create a MATLAB script that can output a matrix representing a circle, where the matrix elements indicate whether a block should be placed at that position (1 for a block, 0 for no block). This output can then be used as a guide for building the circles in Minecraft.

Here's what I have tried so far:

function circleMatrix = generateMinecraftCircle(radius)
    circleMatrix = zeros(2*radius+1, 2*radius+1);
    for x = -radius:radius
        for y = -radius:radius
            if round(sqrt(x^2 + y^2)) == radius
                circleMatrix(x+radius+1, y+radius+1) = 1;
            end
        end
    end
end

This function takes a radius as input and is supposed to output a matrix with ones representing the circle's perimeter. However, I am facing some issues:

1. The circles generated are not as smooth as I would like. They often have jagged edges which don't look great in Minecraft. I'm aiming for a level of smoothness similar to what's achieved by online tools like the Minecraft Circle Generator https://minecraftcirclegenerate.com/, but I'm struggling to replicate this in MATLAB.
2. I am unsure how to optimize this code for larger circles as it gets quite slow.

I would greatly appreciate any suggestions for improving the circle's smoothness and the efficiency of the code. Also, if there's a better approach to achieving this in MATLAB, I am open to trying new methods.

Thank you for your help!

[kainat]

function circleMatrix = generateMinecraftCircle(radius)

% Create an empty matrix

circleMatrix = zeros(2*radius+1, 2*radius+1);

% Loop through all positions

for x = -radius:radius

for y = -radius:radius

% Fill ones for positions close to the circle radius

if abs(sqrt(x^2 + y^2) - radius) < 0.5

circleMatrix(x+radius+1, y+radius+1) = 1;

end

end

end

end

How to use it:

matlab

Copy code

radius = 5; % Set your desired circle radius

circleMatrix = generateMinecraftCircle(radius);

imshow(circleMatrix) % To see the circle

✅ This version is:

Easy for beginners to understand

Produces smoother circles (less jagged edges)

Can be used directly as a guide for building Minecraft circles

Answer 1

[Florian Bidaud]

You need a bit more resolution in your circle, and I would go for finding the minimum of the equation rather than rounding the result. However, I am not familiar with minecraft, I am not sure that you can split the radius and the resolution as I just did as you might be limited be the number of squares if you really want a explicit radius rather than a shape.

resolution = 10; % Higher resolution
circleMatrix = generateMinecraftCircle(10,resolution);
[r,c] = find(circleMatrix);
scatter(c/resolution,r/resolution)
xlim([0 20])
ylim([0 20])

resolution = 1; % Lower resolution
circleMatrix = generateMinecraftCircle(10,resolution);
[r,c] = find(circleMatrix);
scatter(c/resolution,r/resolution)
xlim([0 20])
ylim([0 20])

function circleMatrix = generateMinecraftCircle(radius,resolution)
    radius = resolution*radius;
    circleMatrix = zeros(2*radius+1, 2*radius+1);
    for x = -radius:radius
        circleMatrix(x+radius+1,:) = abs(x^2 + (-radius:radius).^2-radius^2)==min(abs(x^2 + (-radius:radius).^2-radius^2));
    end
end