Base64 Encoding in OpenSCAD

OpenSCAD does not have built-in support for base64 encoding/decoding. However, we can implement a basic version of base64 encoding and decoding using string manipulation functions. Note that this implementation is for educational purposes and may not be as efficient or robust as a built-in function.

// Base64 encoding and decoding in OpenSCAD

// Define the base64 character set
function base64_chars() = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

// Encode a string to base64
function base64_encode(str) =
    let(
        bytes = [for (i = [0:len(str)-1]) ord(str[i])],
        padded_bytes = concat(bytes, [0, 0, 0]),
        encoded = [
            for (i = [0:3:len(bytes)-1])
            let(
                n = (padded_bytes[i] << 16) + (padded_bytes[i+1] << 8) + padded_bytes[i+2],
                c1 = (n >> 18) & 63,
                c2 = (n >> 12) & 63,
                c3 = (n >> 6) & 63,
                c4 = n & 63
            )
            each [c1, c2, c3, c4]
        ]
    )
    [for (i = [0:len(encoded)-1]) base64_chars()[encoded[i]]];

// Decode a base64 string
function base64_decode(str) =
    let(
        bytes = [for (i = [0:len(str)-1]) search(str[i], base64_chars())[0]],
        decoded = [
            for (i = [0:4:len(bytes)-1])
            let(
                n = (bytes[i] << 18) + (bytes[i+1] << 12) + (bytes[i+2] << 6) + bytes[i+3],
                c1 = (n >> 16) & 255,
                c2 = (n >> 8) & 255,
                c3 = n & 255
            )
            each [c1, c2, c3]
        ]
    )
    [for (i = [0:len(decoded)-1]) chr(decoded[i])];

// Example usage
data = "abc123!?$*&()'-=@~";

// Encode the string
encoded = base64_encode(data);
echo("Encoded:", encoded);

// Decode the string
decoded = base64_decode(encoded);
echo("Decoded:", decoded);

// Print the results
echo("Original:", data);
echo("Encoded :", encoded);
echo("Decoded :", decoded);

This OpenSCAD script defines functions for base64 encoding and decoding. Here’s how it works:

We define the base64 character set using the base64_chars() function.
The base64_encode() function takes a string, converts it to bytes, and then encodes it using the base64 algorithm.
The base64_decode() function takes a base64 encoded string and decodes it back to the original string.
We demonstrate the usage with an example string “abc123!?$*&()’-=@~”.
We encode the string using our base64_encode() function and then decode it using the base64_decode() function.
Finally, we print the original string, the encoded string, and the decoded string.

To run this script, you would typically save it as a .scad file and open it in the OpenSCAD application. The results will be displayed in the console output.

Note that OpenSCAD is primarily a 3D modeling language and doesn’t have built-in support for many string operations or file I/O. This implementation is a basic representation of base64 encoding/decoding and may not handle all edge cases or be as efficient as implementations in general-purpose programming languages.

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Base64 Encoding in OpenSCAD