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zigrtiow: hollow glass sphere.

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This commit is contained in:
Bill Thiede 2022-08-13 17:25:51 -07:00
parent 8adf1bcadb
commit a4baedefec
2 changed files with 12 additions and 1 deletions
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1
zigrtiow/src/main.zig
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@ -97,6 +97,7 @@ pub fn main() anyerror!void {
try tmp_world.add(Hittable{ .sphere = Sphere.init(Point3.init(0, -100.5, -1), 100, material_ground) });
try tmp_world.add(Hittable{ .sphere = Sphere.init(Point3.init(0, 0, -1), 0.5, material_center) });
try tmp_world.add(Hittable{ .sphere = Sphere.init(Point3.init(-1, 0, -1), 0.5, material_left) });
try tmp_world.add(Hittable{ .sphere = Sphere.init(Point3.init(-1, 0, -1), -0.4, material_left) });
try tmp_world.add(Hittable{ .sphere = Sphere.init(Point3.init(1, 0, -1), 0.5, material_right) });
const world = Hittable{ .hittable_list = tmp_world };

12
zigrtiow/src/material.zig
View File

@ -1,3 +1,4 @@
const std = @import("std");
const vec = @import("./vec.zig");
const Ray = @import("./ray.zig").Ray;
const HitRecord = @import("./hittable.zig").HitRecord;
@ -6,6 +7,7 @@ const Vec3 = vec.Vec3;
const Color = vec.Color;
const random_unit_vector = vec.random_unit_vector;
const random_in_unit_sphere = vec.random_in_unit_sphere;
const pow = std.math.pow;
pub const Material = union(enum) {
labertian: Labertian,
@ -68,6 +70,8 @@ pub const Metal = struct {
}
};
var prng = std.rand.DefaultPrng.init(0);
const rand = prng.random();
pub const Dielectric = struct {
ir: f32, // Index of Refraction
@ -80,7 +84,7 @@ pub const Dielectric = struct {
const sin_theta = @sqrt(1 - cos_theta * cos_theta);
const cannot_refract = refraction_ratio * sin_theta > 1;
const direction = if (cannot_refract)
const direction = if (cannot_refract or reflectance(cos_theta, refraction_ratio) > rand.float(f32))
reflect(unit_direction, rec.normal)
else
refract(unit_direction, rec.normal, refraction_ratio);
@ -91,4 +95,10 @@ pub const Dielectric = struct {
.scattered = scattered,
};
}
fn reflectance(cosine: f32, ref_idx: f32) f32 {
// Use Schlick's approximation for reflectance.
var r0 = (1 - ref_idx) / (1 + ref_idx);
r0 = r0 * r0;
return r0 + (1 - r0) * pow(f32, (1 - cosine), 5);
}
};