refactor physics and try to fix a bunch of stuff

main
_ 2021-12-19 00:02:52 +00:00
parent 8e7101dccd
commit 3aeced7c2f
2 changed files with 270 additions and 206 deletions

View File

@ -127,6 +127,11 @@ impl GameGraphics {
#[tokio::main] #[tokio::main]
async fn main () -> Result <()> { async fn main () -> Result <()> {
tracing_subscriber::fmt::fmt ()
.with_env_filter (tracing_subscriber::EnvFilter::from_default_env())
.with_span_events (tracing_subscriber::fmt::format::FmtSpan::CLOSE)
.init ();
let sdl_context = sdl2::init ().map_err (|e| anyhow! ("Can't init SDL: {}", e))?; let sdl_context = sdl2::init ().map_err (|e| anyhow! ("Can't init SDL: {}", e))?;
let video_subsystem = sdl_context.video ().map_err (|e| anyhow! ("Can't get SDL video subsystem: {}", e))?; let video_subsystem = sdl_context.video ().map_err (|e| anyhow! ("Can't get SDL video subsystem: {}", e))?;
let window = video_subsystem.window ("3D platformer", 1280, 720) let window = video_subsystem.window ("3D platformer", 1280, 720)

View File

@ -51,12 +51,13 @@ impl Triangle {
} }
} }
#[derive (Clone, Debug, PartialEq)] #[derive (Clone, Copy, Debug, PartialEq)]
pub struct Collision { pub struct Collision {
t: f32, t: f32,
p_impact: Vec3, p_impact: Vec3,
normal: Vec3, normal: Vec3,
i: usize, i: usize,
c_type: CollisionType,
} }
impl Collision { impl Collision {
@ -70,212 +71,29 @@ impl Collision {
} }
} }
pub fn get_candidate (world: &[Triangle], p0: Vec3, p1: Vec3, radius: f32) #[derive (Clone, Copy, Debug, PartialEq)]
-> Collision pub struct PrimCollision {
{ t: f32,
let radius3 = Vec3::from (( p_impact: Vec3,
radius, normal: Vec3,
radius, }
radius
)); impl PrimCollision {
let v = p1 - p0; pub fn take_if_closer (&self, o: &Self) -> Self {
if o.t < self.t && o.t >= 0.0 {
let mut candidate = Collision { o.clone ()
t: 2.0,
p_impact: Default::default (),
normal: Default::default (),
i: 0,
};
for (i, tri) in world.iter ().enumerate () {
let tri_min = tri.min () - radius3;
let tri_max = tri.max () + radius3;
let ray_min = p0.min (p1);
let ray_max = p0.max (p1);
if
ray_max.x < tri_min.x || ray_min.x > tri_max.x ||
ray_max.y < tri_min.y || ray_min.y > tri_max.y ||
ray_max.z < tri_min.z || ray_min.z > tri_max.z
{
// AABB reject
continue;
} }
else {
// Collision for each triangle is roughly split into: self.clone ()
// Face collisions
// Edge collisions
// Vertex collisions
let normal = Vec3::cross (tri.verts [2] - tri.verts [1], tri.verts [1] - tri.verts [0]).normalize ();
let speed_towards_face = -Vec3::dot (v, normal);
// Face collisions
if speed_towards_face >= 0.0 {
let distance_to_face0 = Vec3::dot (normal, p0 - tri.verts [0]) - radius;
let distance_to_face1 = Vec3::dot (normal, p1 - tri.verts [0]) - radius;
let passed_plane = distance_to_face0 > 0.0 && distance_to_face1 < 0.0;
if passed_plane {
let denom = distance_to_face0 - distance_to_face1;
let t_times_denom = distance_to_face0;
// Because of previous early returns we know that 0.0 < t < 1.0
let p_impact_times_denom = p0 * (denom - t_times_denom) + p1 * (t_times_denom);
let impact_inside_tri = (|| {
for j in 0..3 {
let a = tri.verts [j];
let b = tri.verts [(j + 1) % 3];
let tangent = Vec3::cross (b - a, normal);
if Vec3::dot (tangent, p_impact_times_denom - a * denom) < 0.0 {
return false;
}
}
true
})();
if impact_inside_tri {
// Stop it
let c = Collision {
t: t_times_denom / denom,
p_impact: p_impact_times_denom / denom,
normal,
i,
};
candidate = candidate.take_if_closer (&c);
// goto triangle_collided
}
}
}
// Edge collisions
let ray_dir = (p1 - p0).normalize ();
for j in 0..3 {
let a = tri.verts [j];
let b = tri.verts [(j + 1) % 3];
let cylinder_axis = (b - a).normalize ();
let third_axis = Vec3::cross (cylinder_axis, ray_dir).normalize ();
let perp_ray_axis = Vec3::cross (third_axis, cylinder_axis);
let into_triangle = Vec3::cross (cylinder_axis, normal);
let a_minus_p0 = a - p0;
let a_ray = Vec2::from ((
Vec3::dot (a_minus_p0, perp_ray_axis),
Vec3::dot (a_minus_p0, third_axis)
));
// a_ray is now in a space where X is the ray's t,
// Z is the cylinder axis (and irrelevant for now),
// and Y is the cross of those.
// I forgot the maths word for this
let discriminant = radius * radius - a_ray.y * a_ray.y;
if discriminant < 0.0 {
// No possible collision
continue;
}
let denom = (p1 - p0).length ();
let t_times_denom = a_ray.x - discriminant.sqrt ();
let t = t_times_denom / denom;
if t_times_denom < 0.0 || t_times_denom > denom {
// The cylinder is along the line,
// but outside the line segment
//triangles_hit.push_back (i);
continue;
}
let p_impact_times_denom = p0 * (denom - t_times_denom) + p1 * (t_times_denom);
let p_impact = p_impact_times_denom / denom;
let impact_along_cylinder = Vec3::dot (cylinder_axis, p_impact);
let a_along_cylinder = Vec3::dot (cylinder_axis, a);
if impact_along_cylinder < a_along_cylinder || impact_along_cylinder > Vec3::dot (cylinder_axis, b)
{
// The infinite cylinder is on the line segment,
// but the finite cylinder is not.
//cout << "Finite cylinder reject" << endl;
continue;
}
let edge_normal = (p_impact - (a + (impact_along_cylinder - a_along_cylinder) * cylinder_axis)).normalize ();
let speed_towards_edge = -Vec3::dot (v, edge_normal);
let speed_into_triangle = Vec3::dot (v, into_triangle);
if speed_towards_edge > 0.0 && speed_into_triangle >= 0.0 {
let c = Collision {
t: t_times_denom / denom,
p_impact,
normal: edge_normal,
i,
};
candidate = candidate.take_if_closer (&c);
}
}
// Vertex collisions
for j in 0..3 {
let a = tri.verts [j];
let a_minus_p0 = a - p0;
let a_ray_x = Vec3::dot (a_minus_p0, ray_dir);
let nearest_on_ray = p0 + a_ray_x * ray_dir;
let a_ray_y = (a - nearest_on_ray).length ();
let discriminant = radius * radius - a_ray_y * a_ray_y;
if discriminant < 0.0 {
// The sphere is not on the line
continue;
}
let t = (a_ray_x - discriminant.sqrt ()) / (p1 - p0).length ();
if t < 0.0 || t > 1.0 {
// The sphere is along the line,
// but outside the line segment
continue;
}
let p_impact = p0 * (1.0 - t) + p1 * (t);
let vert_normal = (p_impact - a).normalize ();
// I skip the speed check here cause I'm pretty sure
// the previous work makes it redundant
let c = Collision {
t,
p_impact,
normal: vert_normal,
i,
};
candidate = candidate.take_if_closer (&c);
} }
} }
}
candidate
#[derive (Clone, Copy, Debug, PartialEq)]
enum CollisionType {
Face,
Edge,
Vert,
} }
pub struct Params { pub struct Params {
@ -305,6 +123,7 @@ pub fn step (
let candidate = get_candidate (world, old_pos, new_pos, radius); let candidate = get_candidate (world, old_pos, new_pos, radius);
if candidate.t <= 1.0 { if candidate.t <= 1.0 {
tracing::debug! ("Tri {}, type {:?}", candidate.i, candidate.c_type);
t_remaining *= 1.0 - candidate.t; t_remaining *= 1.0 - candidate.t;
let speed_towards_normal = -Vec3::dot (new_vel, candidate.normal); let speed_towards_normal = -Vec3::dot (new_vel, candidate.normal);
@ -339,6 +158,246 @@ pub fn step (
} }
} }
pub fn get_candidate (world: &[Triangle], p0: Vec3, p1: Vec3, radius: f32)
-> Collision
{
let radius3 = Vec3::from ((
radius,
radius,
radius
));
let v = p1 - p0;
let mut candidate = Collision {
t: 2.0,
p_impact: Default::default (),
normal: Default::default (),
i: 0,
c_type: CollisionType::Face,
};
for (i, tri) in world.iter ().enumerate () {
let tri_min = tri.min () - radius3;
let tri_max = tri.max () + radius3;
let ray_min = p0.min (p1);
let ray_max = p0.max (p1);
if
ray_max.x < tri_min.x || ray_min.x > tri_max.x ||
ray_max.y < tri_min.y || ray_min.y > tri_max.y ||
ray_max.z < tri_min.z || ray_min.z > tri_max.z
{
// AABB reject
// tracing::trace! ("AABB reject");
continue;
}
// Collision for each triangle is roughly split into:
// Face collisions
// Edge collisions
// Vertex collisions
if let Some (c) = get_candidate_face (&tri, p0, p1, radius) {
candidate = candidate.take_if_closer (&Collision {
t: c.t,
p_impact: c.p_impact,
normal: c.normal,
i,
c_type: CollisionType::Face,
});
}
// Edge collisions
for j in 0..3 {
let a = tri.verts [j];
let b = tri.verts [(j + 1) % 3];
if let Some (c) = get_candidate_edge (a, b, p0, p1, radius) {
candidate = candidate.take_if_closer (&Collision {
t: c.t,
p_impact: c.p_impact,
normal: c.normal,
i,
c_type: CollisionType::Edge,
});
}
}
// Vertex collisions
for j in 0..3 {
let a = tri.verts [j];
if let Some (c) = get_candidate_vert (a, p0, p1, radius) {
candidate = candidate.take_if_closer (&Collision {
t: c.t,
p_impact: c.p_impact,
normal: c.normal,
i,
c_type: CollisionType::Vert,
});
}
}
}
candidate
}
fn get_candidate_face (tri: &Triangle, p0: Vec3, p1: Vec3, radius: f32)
-> Option <PrimCollision>
{
let radius3 = Vec3::from ((
radius,
radius,
radius
));
let v = p1 - p0;
let normal = Vec3::cross (tri.verts [2] - tri.verts [1], tri.verts [1] - tri.verts [0]).normalize ();
let distance_to_face0 = Vec3::dot (normal, p0 - tri.verts [0]) - radius;
let distance_to_face1 = Vec3::dot (normal, p1 - tri.verts [0]) - radius;
if distance_to_face0 < 0.0 || distance_to_face1 > 0.0 {
tracing::trace! ("passed_plane {} {}", distance_to_face0, distance_to_face1);
return None;
}
let denom = distance_to_face0 - distance_to_face1;
let t_times_denom = distance_to_face0;
// Because of previous early returns we know that 0.0 < t < 1.0
let p_impact_times_denom = p0 * (denom - t_times_denom) + p1 * (t_times_denom);
for j in 0..3 {
let a = tri.verts [j];
let b = tri.verts [(j + 1) % 3];
let tangent = Vec3::cross (b - a, normal);
if Vec3::dot (tangent, p_impact_times_denom - a * denom) < 0.0 {
// tracing::trace! ("impact_inside_tri");
return None;
}
}
Some (PrimCollision {
t: t_times_denom / denom,
p_impact: p_impact_times_denom / denom,
normal,
})
}
fn get_candidate_edge (a: Vec3, b: Vec3, p0: Vec3, p1: Vec3, radius: f32)
-> Option <PrimCollision>
{
let cylinder_axis = (b - a).normalize ();
let third_axis = Vec3::cross (cylinder_axis, p1 - p0).normalize ();
let perp_ray_axis = Vec3::cross (third_axis, cylinder_axis);
let a_minus_p0 = a - p0;
let a_ray = Vec2::from ((
Vec3::dot (a_minus_p0, perp_ray_axis),
Vec3::dot (a_minus_p0, third_axis)
));
// a_ray is now in a space where X is the ray's t,
// Z is the cylinder axis (and irrelevant for now),
// and Y is the cross of those.
// I forgot the maths word for this
let discriminant = radius * radius - a_ray.y * a_ray.y;
if discriminant < 0.0 {
// No possible collision
// println! ("No possible collision");
return None;
}
let denom = (p1 - p0).length ();
let t_times_denom = a_ray.x - discriminant.sqrt ();
let t = t_times_denom / denom;
if t < 0.0 || t > 1.0 {
// The cylinder is along the line,
// but outside the line segment
//triangles_hit.push_back (i);
// tracing::trace! ("Cylinder is along line but outside line segment {}", t);
return None;
}
let p_impact = p0 * (1.0 - t) + p1 * (t);
let impact_along_cylinder = Vec3::dot (cylinder_axis, p_impact);
let a_along_cylinder = Vec3::dot (cylinder_axis, a);
if impact_along_cylinder < a_along_cylinder || impact_along_cylinder > Vec3::dot (cylinder_axis, b)
{
// The infinite cylinder is on the line segment,
// but the finite cylinder is not.
// tracing::trace! ("Finite cylinder reject");
return None;
}
let edge_normal = (p_impact - (a + (impact_along_cylinder - a_along_cylinder) * cylinder_axis)).normalize ();
//let into_triangle = Vec3::cross (cylinder_axis, normal);
let speed_towards_edge = -Vec3::dot (p1 - p0, edge_normal);
//let speed_into_triangle = Vec3::dot (p1 - p0, into_triangle);
if ! (speed_towards_edge > 0.0 /*&& speed_into_triangle >= 0.0*/) {
// tracing::trace! ("speeds are wrong");
return None;
}
Some (PrimCollision {
t,
p_impact,
normal: edge_normal,
})
}
fn get_candidate_vert (a: Vec3, p0: Vec3, p1: Vec3, radius: f32)
-> Option <PrimCollision>
{
let a_minus_p0 = a - p0;
let ray_dir = (p1 - p0).normalize ();
let a_ray_x = Vec3::dot (a_minus_p0, ray_dir);
let nearest_on_ray = p0 + a_ray_x * ray_dir;
let a_ray_y = (a - nearest_on_ray).length ();
let discriminant = radius * radius - a_ray_y * a_ray_y;
if discriminant < 0.0 {
// The sphere is not on the line
return None;
}
let t = (a_ray_x - discriminant.sqrt ()) / (p1 - p0).length ();
if t < 0.0 || t > 1.0 {
// The sphere is along the line,
// but outside the line segment
return None;
}
let p_impact = p0 * (1.0 - t) + p1 * (t);
let vert_normal = (p_impact - a).normalize ();
// I skip the speed check here cause I'm pretty sure
// the previous work makes it redundant
Some (PrimCollision {
t,
p_impact,
normal: vert_normal,
})
}
#[cfg (test)] #[cfg (test)]
mod test { mod test {
use super::*; use super::*;
@ -449,8 +508,8 @@ mod test {
] { ] {
let a = step (&params, &world, radius, &body_before); let a = step (&params, &world, radius, &body_before);
assert! (a.body.pos.distance_squared (e.body.pos) <= 0.00125); assert! (a.body.pos.distance_squared (e.body.pos) < 0.00125);
assert! (a.body.vel.distance_squared (e.body.vel) <= 0.00125); assert! (a.body.vel.distance_squared (e.body.vel) < 0.00125);
assert_eq! (a.triangles_hit, e.triangles_hit); assert_eq! (a.triangles_hit, e.triangles_hit);
assert_eq! (a.kill, e.kill); assert_eq! (a.kill, e.kill);
} }