diff options
| -rw-r--r-- | src/main.zig | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/src/main.zig b/src/main.zig index 7012bfb..c55bc06 100644 --- a/src/main.zig +++ b/src/main.zig @@ -6,8 +6,9 @@ pub fn unit_vector(v: vec) vec { } pub fn ray_color(r: ray) vec { - if (hit_sphere(vec{ 0, 0, -1 }, 0.5, r)) { - return vec{ 1.0, 0, 0 }; + if (hit_sphere(vec{ 0, 0, -1 }, 0.5, r)) |t| { + const n = unit_vector(r.origin + scalar(t) * r.direction - vec{ 0, 0, -1 }); + return scalar(0.5) * vec{ n[0] + 1, n[1] + 1, n[2] + 1 }; } const direction = unit_vector(r.direction); const t = 0.5 * (direction[1] + 1.0); @@ -21,13 +22,17 @@ pub fn write_color(stdout: anytype, v: vec) !void { try stdout.print("{} {} {}\n", .{ r, g, b }); } -pub fn hit_sphere(center: vec, radius: f32, r: ray) bool { +pub fn hit_sphere(center: vec, radius: f32, r: ray) ?f32 { const oc = r.origin - center; const a = dot(r.direction, r.direction); const b = 2 * dot(oc, r.direction); const c = dot(oc, oc) - radius * radius; const discriminant = b * b - 4 * a * c; - return discriminant > 0; + if (discriminant < 0) { + return null; + } else { + return (-b - @sqrt(discriminant)) / (2 * a); + } } const vec = @Vector(3, f32); |