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

examples/pendulum-simulation/modules/sim/runner.v

@@ -0,0 +1,96 @@
+module sim
+
+import benchmark
+import term
+
+pub type SimRequestHandler = fn (request &SimRequest) ?
+
+pub type SimStartHandler = fn () ?
+
+pub type SimFinishHandler = fn () ?
+
+pub const (
+	default_width  = 600
+	default_height = 600
+)
+
+[params]
+pub struct GridSettings {
+pub:
+	width  int = sim.default_width
+	height int = sim.default_height
+}
+
+pub fn new_grid_settings(settings GridSettings) GridSettings {
+	return GridSettings{
+		...settings
+	}
+}
+
+[params]
+pub struct RunnerSettings {
+pub:
+	grid       GridSettings
+	on_request SimRequestHandler
+	on_start   SimStartHandler
+	on_finish  SimFinishHandler
+}
+
+pub fn run(params SimParams, settings RunnerSettings) {
+	height := settings.grid.height
+	width := settings.grid.width
+
+	if !isnil(settings.on_start) {
+		settings.on_start() or {
+			log(@MOD + '.' + @FN + ': Simulation start handler failed. Error $err')
+		}
+	}
+
+	mut index := 0
+	log('')
+
+	mut bmark := benchmark.new_benchmark()
+	for y in 0 .. height {
+		$if verbose ? {
+			term.clear_previous_line()
+		}
+		log(@MOD + '.' + @FN + ': y: ${y + 1}')
+		for x in 0 .. width {
+			bmark.step()
+			// setup state conditions
+			position := vector(
+				x: 0.1 * ((f64(x) - 0.5 * f64(width - 1)) / f64(width - 1))
+				y: 0.1 * ((f64(y) - 0.5 * f64(height - 1)) / f64(height - 1))
+				z: 0.0
+			)
+			velocity := vector(x: 0, y: 0, z: 0)
+
+			mut state := new_state(
+				position: position
+				velocity: velocity
+			)
+
+			state.satisfy_rope_constraint(params)
+			request := &SimRequest{
+				id: index
+				state: state
+				params: params
+			}
+			settings.on_request(request) or {
+				log(@MOD + '.' + @FN + ': request handler failed. Error $err')
+				bmark.fail()
+				break
+			}
+			index++
+			bmark.ok()
+		}
+	}
+	bmark.stop()
+	println(bmark.total_message(@FN))
+
+	if !isnil(settings.on_finish) {
+		settings.on_finish() or {
+			log(@MOD + '.' + @FN + ': Simulation stop handler failed. Error $err')
+		}
+	}
+}