+
−use crate::{
+
−    common::{GearId, Millis},
+
−    data::GearDataManager,
+
−};
+
−use fpnum::*;
+
−
+
−#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+
−#[repr(transparent)]
+
−pub struct PositionData(pub FPPoint);
+
−
+
−#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+
−#[repr(transparent)]
+
−pub struct VelocityData(pub FPPoint);
+
−
+
−pub struct AffectedByWind;
+
−
+
−pub struct PositionUpdates {
+
−    pub gear_ids: Vec<GearId>,
+
−    pub shifts: Vec<(FPPoint, FPPoint)>,
+
−}
+
−
+
−impl PositionUpdates {
+
−    pub fn new(capacity: usize) -> Self {
+
−        Self {
+
−            gear_ids: Vec::with_capacity(capacity),
+
−            shifts: Vec::with_capacity(capacity),
+
−        }
+
−    }
+
−
+
−    pub fn push(&mut self, gear_id: GearId, old_position: &FPPoint, new_position: &FPPoint) {
+
−        self.gear_ids.push(gear_id);
+
−        self.shifts.push((*old_position, *new_position));
+
−    }
+
−
+
−    pub fn iter(&self) -> impl Iterator<Item = (GearId, &FPPoint, &FPPoint)> {
+
−        self.gear_ids
+
−            .iter()
+
−            .cloned()
+
−            .zip(self.shifts.iter())
+
−            .map(|(id, (from, to))| (id, from, to))
+
−    }
+
−
+
−    pub fn clear(&mut self) {
+
−        self.gear_ids.clear();
+
−        self.shifts.clear();
+
−    }
+
−}
+
−
+
−pub struct PhysicsProcessor {
+
−    gravity: FPNum,
+
−    wind: FPNum,
+
−    position_updates: PositionUpdates,
+
−}
+
−
+
−impl PhysicsProcessor {
+
−    pub fn register_components(data: &mut GearDataManager) {
+
−        data.register::<PositionData>();
+
−        data.register::<VelocityData>();
+
−        data.register::<AffectedByWind>();
+
−    }
+
−
+
−    pub fn new() -> Self {
+
−        Self {
+
−            gravity: fp!(1 / 10),
+
−            wind: fp!(0),
+
−            position_updates: PositionUpdates::new(64),
+
−        }
+
−    }
+
−
+
−    pub fn process_single_tick(&mut self, data: &mut GearDataManager) -> &PositionUpdates {
+
−        let gravity = FPPoint::unit_y() * self.gravity;
+
−        let wind = FPPoint::unit_x() * self.wind;
+
−
+
−        self.position_updates.clear();
+
−
+
−        data.iter()
+
−            .with_tags::<&AffectedByWind>()
+
−            .run(|(vel,): (&mut VelocityData,)| {
+
−                vel.0 += wind;
+
−            });
+
−
+
−        data.iter().run_id(
+
−            |gear_id, (pos, vel): (&mut PositionData, &mut VelocityData)| {
+
−                let old_pos = pos.0;
+
−                vel.0 += gravity;
+
−                pos.0 += vel.0;
+
−                self.position_updates.push(gear_id, &old_pos, &pos.0)
+
−            },
+
−        );
+
−
+
−        &self.position_updates
+
−    }
+
−
+
−    pub fn process_multiple_ticks(
+
−        &mut self,
+
−        data: &mut GearDataManager,
+
−        time_step: Millis,
+
−    ) -> &PositionUpdates {
+
−        let fp_step = time_step.to_fixed();
+
−        let gravity = FPPoint::unit_y() * (self.gravity * fp_step);
+
−        let wind = FPPoint::unit_x() * (self.wind * fp_step);
+
−
+
−        self.position_updates.clear();
+
−
+
−        data.iter()
+
−            .with_tags::<&AffectedByWind>()
+
−            .run(|(vel,): (&mut VelocityData,)| {
+
−                vel.0 += wind;
+
−            });
+
−
+
−        data.iter().run_id(
+
−            |gear_id, (pos, vel): (&mut PositionData, &mut VelocityData)| {
+
−                let old_pos = pos.0;
+
−                vel.0 += gravity;
+
−                pos.0 += vel.0 * fp_step;
+
−                self.position_updates.push(gear_id, &old_pos, &pos.0)
+
−            },
+
−        );
+
−
+
−        &self.position_updates
+
−    }
+
−}