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July 8, 2025 15:58
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cast_ball_triangle
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| // /// Casts a moving ball against a static triangle and returns the first time of impact, if any. | |
| // /// | |
| // /// Checks all triangle features (face, edge, vertex) manually. | |
| // pub fn cast_ball_triangle( | |
| // pos12: &Isometry<f32>, | |
| // vel12: &Vector<f32>, | |
| // g1: &Triangle, | |
| // g2: &Ball, | |
| // options: ShapeCastOptions, | |
| // ) -> Option<(ShapeCastHit, FeatureId)> { | |
| // // TOOD support other options | |
| // let triangle_normal = (g1.b - g1.a).cross(&(g1.c - g1.a)).normalize(); | |
| // // Plane equation: dot((p - a), n) = 0 | |
| // let plane_d = triangle_normal.dot(&g1.a.coords); | |
| // let start_dist = triangle_normal.dot(&pos12.translation.vector) - plane_d; | |
| // let velocity_dot_normal = triangle_normal.dot(&vel12); | |
| // if velocity_dot_normal.abs() < 1e-5 { | |
| // // Sphere is moving parallel to the triangle's plane | |
| // return None; | |
| // } | |
| // // Time of intersection with plane offset by radius | |
| // let t = (g2.radius - start_dist) / velocity_dot_normal; | |
| // if t < 0.0 || t > options.max_time_of_impact { | |
| // return None; | |
| // } | |
| // // Sphere center at time of impact | |
| // let sphere_center_at_impact = pos12.translation.vector + (vel12 * t); | |
| // // Project sphere center onto triangle plane | |
| // let projected_point = sphere_center_at_impact - triangle_normal * ((sphere_center_at_impact - g1.a.coords).dot(&triangle_normal)); | |
| // // Distances to vertices | |
| // let d_a = (projected_point - g1.a.coords).norm_squared(); | |
| // let d_b = (projected_point - g1.b.coords).norm_squared(); | |
| // let d_c = (projected_point - g1.c.coords).norm_squared(); | |
| // // Distances to edges | |
| // let (edge1_dist, _edge1_proj) = point_segment_distance_squared(&projected_point.into(), &g1.a, &g1.b); | |
| // let (edge2_dist, _edge2_proj) = point_segment_distance_squared(&projected_point.into(), &g1.b, &g1.c); | |
| // let (edge3_dist, _edge3_proj) = point_segment_distance_squared(&projected_point.into(), &g1.c, &g1.a); | |
| // // Distance to face (project point onto triangle's plane and check if inside) | |
| // let face_normal = (g1.b - g1.a).cross(&(g1.c - g1.a)).normalize(); | |
| // let v0 = g1.b - g1.a; | |
| // let v1 = g1.c - g1.a; | |
| // let v2 = projected_point - g1.a.coords; | |
| // let dot00 = v0.dot(&v0); | |
| // let dot01 = v0.dot(&v1); | |
| // let dot02 = v0.dot(&v2); | |
| // let dot11 = v1.dot(&v1); | |
| // let dot12 = v1.dot(&v2); | |
| // let denom = dot00 * dot11 - dot01 * dot01; | |
| // let (u, v) = if denom != 0.0 { | |
| // let inv_denom = 1.0 / denom; | |
| // let u = (dot11 * dot02 - dot01 * dot12) * inv_denom; | |
| // let v = (dot00 * dot12 - dot01 * dot02) * inv_denom; | |
| // (u, v) | |
| // } else { | |
| // (-1.0, -1.0) // Degenerate triangle | |
| // }; | |
| // let in_triangle = u >= 0.0 && v >= 0.0 && u + v <= 1.0; | |
| // if !in_triangle { | |
| // return None; | |
| // } | |
| // let face_dist = ((projected_point - g1.a.coords).dot(&face_normal)).abs(); | |
| // // Determine the closest feature | |
| // let mut min_dist = d_a; | |
| // let mut feature = FeatureId::Vertex(0); | |
| // if d_b < min_dist { | |
| // min_dist = d_b; | |
| // feature = FeatureId::Vertex(1); | |
| // } | |
| // if d_c < min_dist { | |
| // min_dist = d_c; | |
| // feature = FeatureId::Vertex(2); | |
| // } | |
| // if edge1_dist < min_dist { | |
| // min_dist = edge1_dist; | |
| // feature = FeatureId::Edge(0); | |
| // } | |
| // if edge2_dist < min_dist { | |
| // min_dist = edge2_dist; | |
| // feature = FeatureId::Edge(1); | |
| // } | |
| // if edge3_dist < min_dist { | |
| // min_dist = edge3_dist; | |
| // feature = FeatureId::Edge(2); | |
| // } | |
| // if in_triangle && face_dist < min_dist { | |
| // feature = FeatureId::Face(0); | |
| // } | |
| // let point_on_triangle = projected_point; | |
| // let point_on_sphere = sphere_center_at_impact - triangle_normal * g2.radius; | |
| // let triangle_normal_as_unit = Unit::new_unchecked(triangle_normal); | |
| // let shape_cast_hit = ShapeCastHit { | |
| // witness1: point_on_triangle.into(), | |
| // witness2: point_on_sphere.into(), | |
| // normal1: triangle_normal_as_unit, | |
| // normal2: -triangle_normal_as_unit, | |
| // time_of_impact: t, | |
| // status: ShapeCastStatus::Converged, // TOOD return penetrating or within target distance | |
| // }; | |
| // return Some((shape_cast_hit, feature)); | |
| // } | |
| // } |
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