Nodes and components

Node is a handle to a node of the scene. Its operations are methods, and each of its components is a field.

Finding nodes

pub fn look(node: Node) {
    let world = scene::get_node("World");
    let enemy = node.get_node("../Enemy");
    let parent = node.parent();
    for child in node.children() {
        log::info(child.name());
    }
    if enemy.is_valid() {
        log::info(enemy.path());
    }
}

A lookup that finds nothing answers no node rather than failing, and is_valid() tells them apart. So does a node that has been freed, which makes the check worth keeping in a field you hold across frames.

Properties

A component's properties read and write as fields, checked against its schema at compile time. A misspelled property does not compile.

pub fn lift(node: Node) {
    let p = node.transform.position;
    node.transform.position = vec3(p.x, p.y + 1.0, p.z);
    node.transform.rotation_euler = vec3(0.0, math::to_radians(90.0), 0.0);
}

Rotations are in radians, and the inspector shows degrees.

Operations

A component's operations are methods on its field. The component reference lists them.

pub fn kick(node: Node) {
    node.body2d.apply_impulse(0.0, 12.0);
    if node.body2d.linear_velocity().x > 5.0 {
        node.body2d.set_linear_velocity(5.0, 0.0);
    }
}

Whole components

Where a component's name is computed, or several keys change at once, pass an any map.

pub fn make_solid(node: Node) {
    node.set_component("body3d", { "kind": physics3d::BODY_DYNAMIC });
    node.patch_component("body3d", { "mass": 2.0, "gravity_scale": 0.5 });
}

set_component replaces a component, and patch_component changes the keys it names. patch_component answers false, and logs why, where the component refuses the value.

Other scripts

There are three ways to reach another script.

The typed form answers nil when the node runs another class. On a match, a call on it is a direct call, with its types checked.

// scripts/scene_tree.bs
pub class SceneTree {
    node: Node,
    pub size: int,
}

// scripts/inspector.bs
use scene_tree;

pub class Inspector {
    node: Node,
}

impl Inspector {
    fn init() {
        let tree: scene_tree::SceneTree? = self.node.get_node("../Tree").script;
        if tree != nil {
            log::info("{tree.unwrap().size}");
        }
    }
}