examples: improve the pendulum simulation, with several modes and diagrams (#13446)

examples/pendulum-simulation/modules/sim/anim/worker.v

@@ -0,0 +1,19 @@
+module anim
+
+import benchmark
+import sim
+import sim.img
+
+fn pixels_worker(mut app App) {
+	mut bmark := benchmark.new_benchmark()
+	for {
+		result := <-app.result_chan or { break }
+		bmark.step()
+		// find the closest magnet
+		pixel_color := img.compute_pixel(result)
+		app.pixels[result.id] = u32(pixel_color.abgr8())
+		bmark.ok()
+	}
+	bmark.stop()
+	println(bmark.total_message(@FN))
+}