draw planes with correct position offset.

js/pixl/public/trixl.html

@@ -383,12 +383,12 @@
			for (var i = 0; i < width; i++) {
				for (var j = 0; j < height; j++) {
					var pos = vec3.create();
					vec3.scaleAndAdd(pos, pos, v, i);
					vec3.scaleAndAdd(pos, pos, w, j);
					var p = vec3.clone(pos);
					vec3.scaleAndAdd(p, p, v, i);
					vec3.scaleAndAdd(p, p, w, j);
					trixl.world.set([
						Math.round(pos[0]), Math.round(pos[1]), Math.round(pos[2])
						Math.round(p[0]), Math.round(p[1]), Math.round(p[2])
					], {color: color || trixl.color});
				}
			}