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12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788const zm = @import("zmath");
const HitRecord = @import("hittable.zig").HitRecord;const Interval = @import("interval.zig").IntervalF32;const Ray = @import("Ray.zig");
const AABB = @This();
x: Interval = Interval.empty,y: Interval = Interval.empty,z: Interval = Interval.empty,
pub fn init(x: Interval, y: Interval, z: Interval) AABB { return AABB{ .x = x, .y = y, .z = z };}
pub fn initP(a: zm.Vec, b: zm.Vec) AABB { // Treat the two points a and b as extrema for the bounding box, so we don't require a // particular minimum/maximum coordinate order. return AABB{ .x = blk: { if (a[0] <= b[0]) break :blk Interval.init(a[0], b[0]) else break :blk Interval.init(b[0], a[0]); }, .y = blk: { if (a[1] <= b[1]) break :blk Interval.init(a[1], b[1]) else break :blk Interval.init(b[1], a[1]); }, .z = blk: { if (a[2] <= b[2]) break :blk Interval.init(a[2], b[2]) else break :blk Interval.init(b[2], a[2]); }, };}
pub fn initAB(a: *const AABB, b: *const AABB) AABB { return AABB{ .x = Interval.initI(a.x, b.x), .y = Interval.initI(a.y, b.y), .z = Interval.initI(a.z, b.z), };}
pub fn axisInterval(self: *const AABB, n: i32) Interval { if (n == 1) return self.y; if (n == 2) return self.z; return self.x;}
pub fn hit(self: *AABB, r: *Ray, ray_t: Interval) bool { if (ray_t.max <= ray_t.min) return false;
const ray_orig = r.orig; const ray_dir = r.dir;
var t = ray_t;
var axis: u8 = 0; while (axis < 3) : (axis += 1) { const ax = self.axisInterval(@intCast(axis)); const adinv = 1.0 / ray_dir[axis];
const t0 = (ax.min - ray_orig[axis]) * adinv; const t1 = (ax.max - ray_orig[axis]) * adinv;
if (t0 < t1) { if (t0 > t.min) t.min = t0; if (t1 < t.max) t.max = t1; } else { if (t1 > t.min) t.min = t1; if (t0 < t.max) t.max = t0; }
if (t.max <= t.min) return false; }
return true;}
pub fn longestAxis(self: *AABB) i32 { if (self.x.size() > self.y.size()) { if (self.x.size() > self.z.size()) { return 0; } else return 2; } else { if (self.y.size() > self.z.size()) { return 1; } else return 2; }}