decimation to <128 chars

index.html

@@ -123,6 +123,7 @@
                 // Convert the 4bpp pixel indices into hex strings
                 let blockMap = {};
                 let uniques = [];
+                /*
                 for (let i = 0; i < chars.length; i++) {
                     let char = chars[i];
                     let block = blocks[char];
@@ -139,6 +140,43 @@
                     }
                     chars[i] = char;
                 }
+                */
+                for (let threshold = 0; threshold < 16; threshold++) {
+                    charIter:
+                    for (let i = 0; i < chars.length; i++) {
+                        let char = chars[i];
+                        let block = blocks[char];
+                        if (!block) {
+                            debugger
+                            throw new Error('missing block');
+                        }
+
+                        fontMatch:
+                        for (let j = 0; j < uniques.length; j++) {
+                            let other = uniques[j];
+                            if (!block) {
+                                debugger
+                                throw new Error('missing other');
+                            }
+                            for (let k = 0; k < blockWidth * blockHeight; k++) {
+                                if (Math.abs(block[k] - other[k]) > threshold) {
+                                    continue fontMatch;
+                                }
+                            }
+                            // we're close enough to reuse a character
+                            chars[i] = j;
+                            continue charIter;
+                        }
+                        // add a new char
+                        chars[i] = uniques.push(block) - 1;
+                    }
+                    if (uniques.length < 128) {
+                        break;
+                    }
+                    // We need to decimate further
+                    blocks = uniques;
+                    uniques = [];
+                }
                 let span = document.querySelector('#block-count');
                 span.textContent = `${uniques.length}`;