1#define_import_path bevy_gaussian_splatting::morph::particle
2
3#import bevy_gaussian_splatting::bindings::{
4    gaussian_uniforms,
5    globals,
6    position_visibility,
7}
8#import bevy_gaussian_splatting::spherical_harmonics::spherical_harmonics_lookup
9#import bevy_gaussian_splatting::transform::{
10    world_to_clip,
11    in_frustum,
12}
13
14struct ParticleBehavior {
15    @location(0) indicies: vec4<i32>,
16    @location(1) velocity: vec4<f32>,
17    @location(2) acceleration: vec4<f32>,
18    @location(3) jerk: vec4<f32>,
19}
20
21@group(3) @binding(7) var<storage, read_write> particle_behaviors: array<ParticleBehavior>;
22
23@compute @workgroup_size(32, 32)
24fn apply_particle_behaviors(
25    @builtin(local_invocation_id) gl_LocalInvocationID: vec3<u32>,
26    @builtin(global_invocation_id) gl_GlobalInvocationID: vec3<u32>,
27) {
28    let behavior_index = gl_GlobalInvocationID.x * 32u + gl_GlobalInvocationID.y;
29    let behavior = particle_behaviors[behavior_index];
30
31    let point_index = behavior.indicies.x;
32    let point = position_visibility[point_index];
33
34    // TODO: add gaussian attribute setters for 4d capability
35
36    let delta_position = behavior.velocity * globals.delta_time + 0.5 * behavior.acceleration * globals.delta_time * globals.delta_time + 1.0 / 6.0 * behavior.jerk * globals.delta_time * globals.delta_time * globals.delta_time;
37    let delta_velocity = behavior.acceleration * globals.delta_time + 0.5 * behavior.jerk * globals.delta_time * globals.delta_time;
38    let delta_acceleration = behavior.jerk * globals.delta_time;
39
40    let new_position = point + delta_position;
41    let new_velocity = behavior.velocity + delta_velocity;
42    let new_acceleration = behavior.acceleration + delta_acceleration;
43
44    workgroupBarrier();
45
46    if (behavior.indicies.x < 0) {
47        return;
48    }
49
50    position_visibility[point_index] = new_position;
51    particle_behaviors[behavior_index].velocity = new_velocity;
52    particle_behaviors[behavior_index].acceleration = new_acceleration;
53}