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

examples/pendulum-simulation/modules/sim/args/parser.v

@@ -0,0 +1,158 @@
+module args
+
+import flag
+import os
+import runtime
+import sim
+import math
+
+// customisable through setting VJOBS
+const max_parallel_workers = runtime.nr_jobs()
+
+[params]
+pub struct ParserSettings {
+	sequential    bool
+	img           bool
+	extra_workers int
+}
+
+pub struct SequentialArgs {
+pub:
+	params   sim.SimParams
+	grid     sim.GridSettings
+	filename string
+}
+
+pub struct ParallelArgs {
+	SequentialArgs
+pub:
+	workers int = args.max_parallel_workers
+}
+
+pub type SimArgs = ParallelArgs | SequentialArgs
+
+pub fn parse_args(config ParserSettings) ?SimArgs {
+	if config.sequential {
+		args := parse_sequential_args() ?
+		return SimArgs(args)
+	} else {
+		args := parse_parallel_args(config.extra_workers) ?
+		return SimArgs(args)
+	}
+}
+
+fn parse_sequential_args() ?SequentialArgs {
+	mut fp := flag.new_flag_parser(os.args)
+	fp.application('vps')
+	fp.version('v0.1.0')
+	fp.limit_free_args(0, 0) ?
+	fp.description('This is a pendulum simulation written in pure V')
+	fp.skip_executable()
+
+	// output parameters
+	width := fp.int('width', `w`, sim.default_width, 'width of the image output. Defaults to $sim.default_width')
+	height := fp.int('height', `h`, sim.default_height, 'height of the image output. Defaults to $sim.default_height')
+	filename := fp.string('output', `o`, 'out.ppm', 'name of the image output. Defaults to out.ppm')
+
+	// simulation parameters
+	rope_length := fp.float('rope-length', 0, sim.default_rope_length, 'rope length to use on simulation. Defaults to $sim.default_rope_length')
+	bearing_mass := fp.float('bearing-mass', 0, sim.default_bearing_mass, 'bearing mass to use on simulation. Defaults to $sim.default_bearing_mass')
+	magnet_spacing := fp.float('magnet-spacing', 0, sim.default_magnet_spacing, 'magnet spacing to use on simulation. Defaults to $sim.default_magnet_spacing')
+	magnet_height := fp.float('magnet-height', 0, sim.default_magnet_height, 'magnet height to use on simulation. Defaults to $sim.default_magnet_height')
+	magnet_strength := fp.float('magnet-strength', 0, sim.default_magnet_strength, 'magnet strength to use on simulation. Defaults to $sim.default_magnet_strength')
+	gravity := fp.float('gravity', 0, sim.default_gravity, 'gravity to use on simulation. Defaults to $sim.default_gravity')
+
+	fp.finalize() or {
+		println(fp.usage())
+		return none
+	}
+
+	params := sim.sim_params(
+		rope_length: rope_length
+		bearing_mass: bearing_mass
+		magnet_spacing: magnet_spacing
+		magnet_height: magnet_height
+		magnet_strength: magnet_strength
+		gravity: gravity
+	)
+
+	grid := sim.new_grid_settings(
+		width: width
+		height: height
+	)
+
+	args := SequentialArgs{
+		params: params
+		filename: filename
+		grid: grid
+	}
+
+	sim.log('$args')
+
+	return args
+}
+
+fn parse_parallel_args(extra_workers int) ?ParallelArgs {
+	mut fp := flag.new_flag_parser(os.args)
+	fp.application('vps')
+	fp.version('v0.1.0')
+	fp.limit_free_args(0, 0) ?
+	fp.description('This is a pendulum simulation written in pure V')
+	fp.skip_executable()
+
+	workers := fp.int('workers', 0, args.max_parallel_workers, 'amount of workers to use on simulation. Defaults to $args.max_parallel_workers')
+
+	// output parameters
+	width := fp.int('width', `w`, sim.default_width, 'width of the image output. Defaults to $sim.default_width')
+	height := fp.int('height', `h`, sim.default_height, 'height of the image output. Defaults to $sim.default_height')
+	filename := fp.string('output', `o`, 'out.ppm', 'name of the image output. Defaults to out.ppm')
+
+	// simulation parameters
+	rope_length := fp.float('rope-length', 0, sim.default_rope_length, 'rope length to use on simulation. Defaults to $sim.default_rope_length')
+	bearing_mass := fp.float('bearing-mass', 0, sim.default_bearing_mass, 'bearing mass to use on simulation. Defaults to $sim.default_bearing_mass')
+	magnet_spacing := fp.float('magnet-spacing', 0, sim.default_magnet_spacing, 'magnet spacing to use on simulation. Defaults to $sim.default_magnet_spacing')
+	magnet_height := fp.float('magnet-height', 0, sim.default_magnet_height, 'magnet height to use on simulation. Defaults to $sim.default_magnet_height')
+	magnet_strength := fp.float('magnet-strength', 0, sim.default_magnet_strength, 'magnet strength to use on simulation. Defaults to $sim.default_magnet_strength')
+	gravity := fp.float('gravity', 0, sim.default_gravity, 'gravity to use on simulation. Defaults to $sim.default_gravity')
+
+	fp.finalize() or {
+		println(fp.usage())
+		return none
+	}
+
+	params := sim.sim_params(
+		rope_length: rope_length
+		bearing_mass: bearing_mass
+		magnet_spacing: magnet_spacing
+		magnet_height: magnet_height
+		magnet_strength: magnet_strength
+		gravity: gravity
+	)
+
+	grid := sim.new_grid_settings(
+		width: width
+		height: height
+	)
+
+	args := ParallelArgs{
+		params: params
+		filename: filename
+		grid: grid
+		workers: get_workers(workers, extra_workers)
+	}
+
+	sim.log('$args')
+
+	return args
+}
+
+[inline]
+fn get_workers(workers int, extra_workers int) int {
+	result := if workers + extra_workers <= args.max_parallel_workers {
+		workers
+	} else {
+		args.max_parallel_workers - extra_workers
+	}
+
+	return math.max(1, result)
+}