engine/gavania-core/src/game/content/lightning.rs

use std::{collections::HashMap, str::FromStr};

use cgmath::{vec2, Deg, Rad, Vector2, Vector3};
use entity_manager::*;

use crate::*;

pub struct LightningMarker;

impl EntityComponent for LightningMarker {
    fn name(&self) -> &str {
        Self::debug_name()
    }
}

impl ComponentDebug for LightningMarker {
    fn debug_name() -> &'static str {
        "LightningMarker"
    }
}

pub struct Lightning {
    pub thickness: f32,
    pub lines: Vec<Vector2<f32>>,
}

impl Lightning {
    const WIDTH: f32 = 0.25;
    const LENGTH: f32 = 1.0;
    const DIRECTION: Vector2<f32> = Vector2::new(1.0, 0.0);

    pub fn new(thickness: f32) -> Self {
        Self {
            thickness,
            lines: Self::create_lines(),
        }
    }

    pub fn create_vertices(&self) -> Vec<Vector2<f32>> {
        self.lines
            .iter()
            .skip(1)
            .enumerate()
            .map(|(index, p)| {
                let prev_p = self.lines[index];

                let tangent = prev_p - p;
                let normal = vec2(-tangent.y, tangent.x).normalize();

                let p1 = prev_p - normal * 0.5 * self.thickness;
                let p2 = p - normal * 0.5 * self.thickness;
                let p3 = p + normal * 0.5 * self.thickness;
                let p4 = prev_p + normal * 0.5 * self.thickness;

                vec![p1, p2, p3, p3, p4, p1]
            })
            .flatten()
            .collect()
    }

    pub fn create_entity(
        &self,
        game_handle: &GameHandle,
        scene: &Scene,
        position: Vector3<f32>,
        target: Vector3<f32>,
    ) -> Result<EntityObject> {
        let game = game_handle.upgrade();
        let mut entity = game.engine().assets().empty_entity();

        #[cfg(debug_assertions)]
        {
            entity.debug_name = Some("Lightning".to_string());
        }

        let tangent = (target - position).truncate();
        let scale = tangent.magnitude();
        let angle = tangent.angle(Self::DIRECTION);
        let angle_offset: Rad<f32> = Deg(90.0).into();
        let height = position.z;

        let mut mesh = AssetMesh::new(&scene.device(), scene.render_type())?;
        mesh.set_name("Lightning");

        let data: Vec<PositionOnly> = self
            .create_vertices()
            .into_iter()
            .rev()
            .map(|p| PositionOnly::new(p.extend(0.0)))
            .collect();

        let vertex_buffer = Buffer::builder()
            .set_memory_usage(MemoryUsage::CpuOnly)
            .set_usage(VK_BUFFER_USAGE_STORAGE_BUFFER_BIT | VK_BUFFER_USAGE_VERTEX_BUFFER_BIT)
            .set_data(&data)
            .build(scene.device().clone())?;

        mesh.add_primitive(
            vertex_buffer,
            None,
            None,
            PrimitiveMaterial {
                color: Color::from_str("#2660ff")?.into(),

                ..Default::default()
            },
            true,
        )?;

        entity.insert_component(Draw::new(vec![mesh]));

        let audio = Audio::new(
            &game.engine().context(),
            [(
                SOUND_CREATE_KEY.to_string(),
                game_handle.build_data_path("sounds/shot2.ogg"),
            )]
            .into_iter()
            .collect::<HashMap<_, _>>(),
        )?;

        entity.insert_component(audio);

        let location = Location::new_and_setup(&mut entity)?;
        location.set_position(position);
        location.set_scale_uniform(scale);
        location.set_rotation(angle - angle_offset);

        entity.insert_component(LightningMarker);
        entity.insert_component(BoundingBox {
            min: [0.0, -0.25, 0.0],
            max: [1.0, 0.25, 1.0],
        });

        println!(
            "Lightning created with components: {:#?}",
            entity.component_names()
        );

        Ok(entity)
    }

    fn create_lines() -> Vec<Vector2<f32>> {
        let mut lines = Vec::new();

        for _ in 0..50 {
            lines.push(vec2(Random::range_f32(0.0, Self::LENGTH), 0.0));
        }

        lines.sort_by(|lhs, rhs| lhs.x.partial_cmp(&rhs.x).unwrap());

        [vec2(0.0, 0.0)]
            .into_iter()
            .chain(
                lines
                    .into_iter()
                    .map(|p| vec2(p.x, Random::range_f32(-Self::WIDTH, Self::WIDTH))),
            )
            .chain([vec2(1.0, 0.0)].into_iter())
            .collect()
    }
}