# Symbol and Schematic > Symbol draws one circuit part: SymbolKind::Resistor, Capacitor, Inductor, VoltageSource, CurrentSource, Ground, Opamp (Manim-circuit's set), and Battery… Page: https://fframes-kit.pages.dev/docs/physics/symbol-and-schematic/ Cargo feature: `physics` (`fframes-kit = { version = "..", features = ["physics"] }`) `Symbol` draws one circuit part: `SymbolKind::Resistor`, `Capacitor`, `Inductor`, `VoltageSource`, `CurrentSource`, `Ground`, `Opamp` (Manim-circuit's set), and `Battery`, `Switch { closes_at }`, `Bulb` and `Diode`. It sits at `at`, turned `rotation` degrees counterclockwise, `size` units from its middle to a terminal, with an optional `label`. `terminal(name)` gives where a wire attaches: `a` and `b` for every two-terminal part (also `-` and `+` on the sources and the battery, `anode` and `cathode` on the diode), `a` on top of `Ground`, and `-`, `+`, `out` on the op-amp. Gallery scenes: `Symbol`, `Schematic`. Gallery clip of `Symbol`: https://fframes-kit.pages.dev/media/scenes/Symbol-1b7d8ad4.mp4 Gallery clip of `Schematic`: https://fframes-kit.pages.dev/media/scenes/Schematic-f1d8bb06.mp4 Show a symbol on its own, with a switch that closes after 1.5 seconds: ```rust use fframes_kit::prelude::*; fn symbol<'a>(ui: &mut Ui<'a, '_, '_>) -> Svgr<'a> { ui.show(Symbol { kind: SymbolKind::Switch { closes_at: Some(1.5) }, at: (0.0, 0.0), size: 0.9, label: "switch", enter: Some(Create::default().into()), ..ui.defaults() }) } ``` `Schematic` wires symbols together. A `Connection` runs from a pin to a pin, a terminal `(symbol index, name)` or a point `(x, y)` to end on another wire, through the corners given with `via`. Without corners a wire whose ends are not in line goes horizontally, then vertically. There is no automatic routing. Junction dots mark where three or more conductors meet. From `current_at` the current flows as dots along every wire (reversed with a negative `current(..)`, none with 0) and bulbs light up. Each wire moves its own dots, so they do not line up across a junction. A wire with a missing terminal is skipped, and `unresolved()` lists it. ```rust use fframes_kit::prelude::*; fn figure<'a>(ui: &mut Ui<'a, '_, '_>) -> Svgr<'a> { let theme = ui.theme.clone(); let part = |kind, at, rotation, label| Symbol { kind, at, rotation, label, ..Symbol::themed(&theme) }; ui.show(Schematic { symbols: vec![ part(SymbolKind::Battery, (-3.0, 0.0), 90.0, "9 V"), part(SymbolKind::Resistor, (0.0, 1.5), 0.0, "220R"), part(SymbolKind::Bulb, (3.0, 0.0), 90.0, ""), ], wires: vec![ Connection::new((0, "+"), (1, "a")).via([(-3.0, 1.5)]), Connection::new((1, "b"), (2, "b")).via([(3.0, 1.5)]), Connection::new((2, "a"), (0, "-")).via([(3.0, -1.5), (-3.0, -1.5)]), ], current_at: Some(1.0), ..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`). ### Symbol A circuit symbol, Manim-circuit's `Resistor`, `Capacitor` and the rest: `kind` drawn at `at` (units of `ui.space`), turned `rotation` degrees counterclockwise, `size` units from its middle to a terminal. `terminal` gives where a wire attaches. The label is drawn beside it, on the other side with `flip_label`; an empty one is not drawn. The symbol draws with `enter`, the label and a bulb's glow (`lit`, 0 to 1) fade with `parts_enter`. A `Schematic` wires symbols together. | Field | Type | Default | Description | | --- | --- | --- | --- | | `kind` | `SymbolKind` | `SymbolKind::Resistor` | Which part to draw: resistor, capacitor, inductor, source, ground, op-amp, battery, switch, bulb or diode. | | `at` | `(f64, f64)` | `(0.0, 0.0)` | The middle of the symbol, in units of `ui.space`. | | `rotation` | `f64` | `0.0` | Degrees counterclockwise to turn the symbol around its middle. | | `size` | `f64` | `0.6` | Units of `ui.space` from the middle to a terminal. | | `label` | `&str` | `""` | Text drawn beside the symbol; empty for none. | | `flip_label` | `bool` | `false` | Puts the label on the opposite side of the symbol. | | `lit` | `f32` | `0.0` | Glow of a bulb from 0 (off) to 1 (full); other symbols ignore it. | | `color` | `Color` | `theme.colors.text` | Colour of the symbol's lines and fills. | | `label_color` | `Color` | `theme.colors.text` | Colour of the label. | | `glow_color` | `Color` | `theme.colors.highlight` | Colour of a bulb's glow. | | `stroke_width` | `f32` | `theme.stroke.regular` | Line width in pixels; the battery's short plate is 2.5 times as thick. | | `enter` | `Option` | `None` | How the symbol draws in; `None` shows it from the start. | | `exit` | `Option` | `None` | How the symbol leaves at the end of the container; `None` stays. | | `parts_enter` | `Option` | `None` | How the label and the bulb's glow fade in; `None` for none. | | `parts_exit` | `Option` | `None` | How the label and the bulb's glow fade out before the end; `None` for none. | Methods: - `fn terminal(&self, name: &str) -> Option<(f64, f64)>`: Where the terminal `name` is, in units of `ui.space`; `None` for a name the kind does not have. - `fn lever_angle(&self, now: f32) -> f64`: The angle of a switch's lever at `now` seconds, from open (35°) to closed (0). Feature `physics` · [Source](https://github.com/khanhthanhdev/fframes-kit/blob/main/fframes-kit/src/kits/physics/schematic.rs#L108) ### Schematic Symbols wired together. `symbols` are drawn as they are (their `enter` and `exit` aside) and `wires` connect their terminals at right angles through the corners each one gives; there is no automatic routing. Where three or more conductors meet (a terminal with two wires, or a wire ending on another) a junction dot is drawn with `junctions`. | Field | Type | Default | Description | | --- | --- | --- | --- | | `symbols` | `Vec` | `Vec::new()` | The parts of the circuit, each placed with its own position, rotation and label. | | `wires` | `Vec` | `Vec::new()` | The wires between terminals or points, in order; a wire with a missing terminal is left out. | | `current_at` | `Option` | `None` | Seconds of local time when the current starts to flow and bulbs light up; `None` for no current. | | `current_speed` | `f32` | `160.0` | Speed of the current dots in pixels per second, before each wire's own `current` factor. | | `dot_spacing` | `f32` | `56.0` | Pixels between two current dots along a wire. | | `junctions` | `bool` | `true` | Draws a dot where three or more conductors meet. | | `wire_color` | `Color` | `theme.colors.text` | Colour of the wires and junction dots. | | `dot_color` | `Color` | `theme.colors.accent` | Colour of the current dots. | | `stroke_width` | `f32` | `theme.stroke.regular` | Width of the wires in pixels. | | `enter` | `Option` | `None` | How the wires and symbols draw in; `None` shows them from the start. | | `exit` | `Option` | `None` | How the wires and symbols leave at the end of the container; `None` stays. | | `parts_enter` | `Option` | `None` | How the labels, current dots and glow fade in; `None` for none. | | `parts_exit` | `Option` | `None` | How the labels, current dots and glow fade out before the end; `None` for none. | Methods: - `fn pin(&self, pin: Pin) -> Option<(f64, f64)>`: Where `pin` is, in units of `ui.space`. - `fn route(&self, wire: &Connection) -> Option>`: The corners of `wire` from its start to its end, in units of `ui.space`, or `None` when one of its ends does not resolve. - `fn unresolved(&self) -> Vec`: The indices of the wires with an end that names a missing symbol or terminal. - `fn flowing(&self, now: f32) -> f32`: Seconds the current has flowed at `now`, 0 before it starts or without it. - `fn junctions(&self) -> Vec<(f64, f64)>`: The points where three or more conductors meet, in units of `ui.space`: the ends of wires, counting a terminal as one conductor and a wire that runs on through the point as two. Feature `physics` · [Source](https://github.com/khanhthanhdev/fframes-kit/blob/main/fframes-kit/src/kits/physics/schematic.rs#L492)