FreeBody

A block with forces (Force::new(name, x, y), in newtons, y up) drawn from its middle, scale units per newton. The arrows grow one after another, each labelled at its tip with its name and magnitude. Then the other forces dim and their sum grows as a dashed arrow labelled net = … N, or net = 0 under the block when they balance. net_force() gives the sum. Gallery scene: FreeBody.

FreeBody 4.5 sPlayUnmuteCopy render command

use fframes_kit::prelude::*;

fn figure<'a>(ui: &mut Ui<'a, '_, '_>) -> Svgr<'a> {
    ui.show(FreeBody {
        forces: vec![
            Force::new("W", 0.0, -5.0),
            Force::new("N", 0.0, 5.0),
            Force::new("F", 6.0, 0.0),
            Force::new("f", -2.0, 0.0),
        ],
        center: (0.0, -0.4),
        scale: 0.45,
        delay: 0.5,
        ..ui.defaults()
    })
}

API

Components are plain structs. Set the fields you need and fill the rest with ..ui.defaults(): the defaults below come from the current theme (theme. values are fields of Theme).

FreeBody

Field	Type	Default	Description
forces	Vec<Force>	Vec::new()	The forces on the block, each with a name and components in newtons (y up).
center	(f64, f64)	(0.0, 0.0)	The middle of the block, where the arrows start, in units of ui.space.
scale	f64	0.5	Units of ui.space per newton.
size	f32	160.0	Side of the square block in pixels.
delay	f32	0.0	Seconds after the local start before the first arrow starts to grow.
grow	f32	0.6	Seconds each arrow takes to grow.
stagger	f32	0.5	Seconds between the start of one arrow and the next.
net	bool	true	Draws the sum of the forces as a dashed arrow after the others, or net = 0 under the block when they balance.
net_name	&str	"net"	The name in the net force’s label, “net = 4 N”.
labels	bool	true	Writes each force’s name at its tip.
magnitudes	bool	true	Adds the magnitude in newtons to each label.
block_color	Color	theme.colors.muted	Colour of the block.
force_color	Color	theme.colors.accent	Colour of the force arrows that have no colour of their own.
net_color	Color	theme.colors.highlight	Colour of the net force arrow and its label.
text_color	Color	theme.colors.text	Colour of the force labels; the net force’s label takes net_color.
stroke_width	f32	theme.stroke.regular	Width of the arrow shafts in pixels.
enter	Option<EnterAnim>	None	How the block draws in; None shows it from the start.
exit	Option<ExitAnim>	None	How the block leaves at the end of the container; None stays.
parts_enter	Option<FadeIn>	None	How the arrows and labels fade in; None for none.
parts_exit	Option<FadeOut>	None	How the arrows and labels fade out before the end; None for none.

Methods:

• fn net_force(&self) -> (f64, f64): The sum of the forces in newtons.
• fn start_of(&self, i: usize) -> f32: Seconds after the local start when force i starts to grow; forces.len() gives the start of the net force.

Feature physics · Source