Preserve all STL assembly faces

SUB Control/web/model-viewer.js

@@ -4,7 +4,8 @@
   const ctx = canvas.getContext('2d');
   let vertices = null, frame = 0, yaw = 0, pitch = 0, zoom = 1;
   let dragging = false, lastX = 0, lastY = 0;
-  const renderScale = .62;
+  // Still below native resolution, but high enough for clean assembly contours.
+  const renderScale = .82;
 
   function parseStl(buffer) {
     const view = new DataView(buffer);
@@ -12,8 +13,7 @@
     const binaryCount = buffer.byteLength >= 84 ? view.getUint32(80, true) : 0;
     const isBinary = binaryCount > 0 && 84 + binaryCount * 50 <= buffer.byteLength;
     if (isBinary) {
-      const stride = Math.max(1, Math.ceil(binaryCount / 14000));
-      for (let t = 0; t < binaryCount; t += stride) {
+      for (let t = 0; t < binaryCount; t++) {
         const offset = 84 + t * 50 + 12;
         for (let v = 0; v < 3; v++) {
           raw.push(view.getFloat32(offset + v * 12, true));
@@ -25,8 +25,7 @@
       const text = new TextDecoder().decode(buffer);
       const matches = [...text.matchAll(/vertex\s+([-+\deE.]+)\s+([-+\deE.]+)\s+([-+\deE.]+)/gi)];
       if (matches.length < 3) throw new Error('This file does not contain a readable STL mesh');
-      const stride = Math.max(1, Math.ceil(matches.length / 42000));
-      for (let i = 0; i + 2 < matches.length; i += 3 * stride) {
+      for (let i = 0; i + 2 < matches.length; i += 3) {
         for (let j = 0; j < 3; j++) raw.push(+matches[i+j][1], +matches[i+j][2], +matches[i+j][3]);
       }
     }
@@ -53,16 +52,19 @@
       return [rx,y*cosP-rz*sinP];
     };
     maskCtx.fillStyle='#fff';
+    maskCtx.beginPath();
     for(let i=0;i<vertices.length;i+=9){
       const a=project(vertices[i],vertices[i+1],vertices[i+2]);
       const b=project(vertices[i+3],vertices[i+4],vertices[i+5]);
       const c=project(vertices[i+6],vertices[i+7],vertices[i+8]);
-      maskCtx.beginPath();
       maskCtx.moveTo(cx+a[0]*size,cy-a[1]*size);
       maskCtx.lineTo(cx+b[0]*size,cy-b[1]*size);
       maskCtx.lineTo(cx+c[0]*size,cy-c[1]*size);
-      maskCtx.closePath();maskCtx.fill();
+      maskCtx.closePath();
     }
+    // Rasterize the union once. Filling faces individually creates faint
+    // antialiased seams that resemble a wireframe on dense assemblies.
+    maskCtx.fill();
     // A filtered copy creates only the exterior contour; triangle boundaries
     // never enter the final image because the source is a single solid mask.
     ctx.save();