Offset lines to not interfere with the clipping plane

Author: remcoder

src/webgl-preview.ts

@@ -475,18 +475,24 @@ export class WebGLPreview {
   }
 
   private renderPathsAsLines(paths: Path[], color: Color): void {
-    console.log(this.clippingPlanes);
     const material = new LineMaterial({
       color: Number(color.getHex()),
       linewidth: this.lineWidth,
       clippingPlanes: this.clippingPlanes
     });
 
     const lineVertices: number[] = [];
+
+    // lines need to be offset. 
+    // The gcode specifies the nozzle height which is the top of the extrusion.
+    // The line doesn't have a constant height in world coords so it should be rendered at horizontal midplane of the extrusion layer.
+    // Otherwise the line will be clipped by the clipping plane.
+    const offset = -this.lineHeight / 2;
+
     paths.forEach((path) => {
       for (let i = 0; i < path.vertices.length - 3; i += 3) {
-        lineVertices.push(path.vertices[i], path.vertices[i + 1], path.vertices[i + 2]);
-        lineVertices.push(path.vertices[i + 3], path.vertices[i + 4], path.vertices[i + 5]);
+        lineVertices.push(path.vertices[i], path.vertices[i + 1] -0.1, path.vertices[i + 2] + offset);
+        lineVertices.push(path.vertices[i + 3], path.vertices[i + 4]-0.1, path.vertices[i + 5] + offset);
       }
     });