elastic_cut3.rs

use wgsparkl_testbed3d::{wgsparkl, RapierData};

use bevy::prelude::*;
use bevy::render::renderer::RenderDevice;
use nalgebra::{vector, DMatrix, Isometry3};
use rapier3d::geometry::HeightField;
use rapier3d::prelude::{ColliderBuilder, RigidBodyBuilder};
use wgsparkl::{
    models::ElasticCoefficients,
    pipeline::MpmData,
    solver::{Particle, ParticleDynamics, ParticlePhase, SimulationParams},
};
use wgsparkl_testbed3d::{AppState, PhysicsContext};

pub fn elastic_cut_demo(
    mut commands: Commands,
    device: Res<RenderDevice>,
    mut app_state: ResMut<AppState>,
) {
    let mut rapier_data = RapierData::default();
    let device = device.wgpu_device();

    let nxz = 50;
    let cell_width = 1.0;
    let mut particles = vec![];
    for i in 0..nxz {
        for j in 0..30 {
            for k in 0..nxz {
                let position = vector![
                    i as f32 + 0.5 - nxz as f32 / 2.0,
                    j as f32 + 0.5 + 60.0,
                    k as f32 + 0.5 - nxz as f32 / 2.0
                ] * cell_width
                    / 2.0;
                let density = 2700.0;
                let radius = cell_width / 4.0;
                particles.push(Particle {
                    position,
                    dynamics: ParticleDynamics::with_density(radius, density),
                    model: ElasticCoefficients::from_young_modulus(10_000_000.0, 0.2),
                    plasticity: None,
                    phase: Some(ParticlePhase {
                        phase: 1.0,
                        max_stretch: f32::MAX,
                    }),
                    color: None,
                });
            }
        }
    }

    if !app_state.restarting {
        app_state.num_substeps = 20;
        app_state.gravity_factor = 4.0;
    };

    let params = SimulationParams {
        gravity: vector![0.0, -9.81, 0.0] * app_state.gravity_factor,
        dt: (1.0 / 60.0) / (app_state.num_substeps as f32),
    };

    let rb = RigidBodyBuilder::fixed().translation(vector![0.0, -4.0, 0.0]);
    let rb_handle = rapier_data.bodies.insert(rb);
    let co = ColliderBuilder::cuboid(100.0, 1.0, 100.0);
    rapier_data
        .colliders
        .insert_with_parent(co, rb_handle, &mut rapier_data.bodies);

    // TODO: use only two rectangle per cutting tool.
    //       We can’t right now since we don’t really sample the triangles.
    for k in 0..3 {
        let heights = DMatrix::zeros(10, 10);
        let heightfield = HeightField::new(heights, vector![35.0, 1.0, 10.0]);
        let (mut vtx, idx) = heightfield.to_trimesh();
        vtx.iter_mut().for_each(|pt| {
            *pt = Isometry3::rotation(vector![1.3, 0.0, 0.0]) * *pt
                + vector![0.0, 10.0, k as f32 * 10.0 - 10.0]
        });
        let rb = RigidBodyBuilder::fixed();
        let rb_handle = rapier_data.bodies.insert(rb);
        let co = ColliderBuilder::trimesh(vtx, idx).unwrap();
        rapier_data
            .colliders
            .insert_with_parent(co, rb_handle, &mut rapier_data.bodies);
    }

    let data = MpmData::new(
        device,
        params,
        &particles,
        &rapier_data.bodies,
        &rapier_data.colliders,
        cell_width,
        60_000,
    );
    commands.insert_resource(PhysicsContext {
        data,
        rapier_data,
        particles,
    });
}