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dielectrics based on snell's law
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src/main.zig
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src/main.zig
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// Setting up the world
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var material_ground = Material.lambertian(zm.f32x4(0.8, 0.8, 0.0, 1.0));
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var material_center = Material.lambertian(zm.f32x4(0.7, 0.3, 0.3, 1.0));
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var material_left = Material.metal(zm.f32x4(0.8, 0.8, 0.8, 1.0), 0.0);
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var material_center = Material.lambertian(zm.f32x4(0.1, 0.2, 0.5, 1.0));
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var material_left = Material.dielectric(1.0 / 1.33);
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var material_right = Material.metal(zm.f32x4(0.8, 0.6, 0.2, 1.0), 1.0);
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var world = HittableList.init(allocator);
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src/material.zig
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src/material.zig
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pub const Material = union(enum) {
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lambertian: Lambertian,
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metal: Metal,
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dielectric: Dielectric,
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pub fn lambertian(albedo: zm.Vec) Material {
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return .{ .lambertian = .{ .albedo = albedo } };
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return .{ .metal = .{ .albedo = albedo, .fuzz = if (fuzz < 1) fuzz else 1.0 } };
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}
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pub fn dielectric(refraction_index: f32) Material {
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return .{ .dielectric = .{ .refraction_index = refraction_index } };
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}
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pub fn scatter(self: *Material, r: *Ray, rec: *hittable.HitRecord, attenuation: *zm.Vec) ?Ray {
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return switch (self.*) {
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.lambertian => |*lambert| lambert.scatter(rec, attenuation),
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.metal => |*met| met.scatter(r, rec, attenuation),
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.dielectric => |*die| die.scatter(r, rec, attenuation),
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};
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}
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};
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return if (zm.dot3(scattered.dir, rec.normal)[0] > 0) scattered else null;
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}
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};
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pub const Dielectric = struct {
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refraction_index: f32,
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pub fn scatter(self: *Dielectric, r: *Ray, rec: *hittable.HitRecord, attenuation: *zm.Vec) ?Ray {
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attenuation.* = zm.f32x4s(1.0);
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const ri = if (rec.front_face) (1.0 / self.refraction_index) else self.refraction_index;
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const unit_direction = zm.normalize3(r.dir);
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const cos_theta = @min(zm.dot3(-unit_direction, rec.normal)[0], 1.0);
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const sin_theta = @sqrt(1.0 - cos_theta * cos_theta);
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const cannot_refract = ri * sin_theta > 1.0;
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const direction = blk: {
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if (cannot_refract) {
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break :blk util.reflect(unit_direction, rec.normal);
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} else {
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break :blk util.refract(unit_direction, rec.normal, ri);
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}
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};
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return Ray.init(rec.p, direction);
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}
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};
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-1
src/util.zig
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src/util.zig
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return (@abs(e[0]) < s) and (@abs(e[1]) < s) and (@abs(e[2]) < s);
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}
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pub fn reflect(v: zm.Vec, n: zm.Vec) zm.Vec {
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pub inline fn reflect(v: zm.Vec, n: zm.Vec) zm.Vec {
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return v - zm.f32x4s(2 * zm.dot3(v, n)[0]) * n;
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}
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pub inline fn refract(uv: zm.Vec, n: zm.Vec, etai_over_etat: f32) zm.Vec {
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const cos_theta = @min(zm.dot3(-uv, n)[0], 1.0);
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const r_out_perp = zm.f32x4s(etai_over_etat) * (uv + zm.f32x4s(cos_theta) * n);
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const r_out_parallel = zm.f32x4s(-@sqrt(@abs(1.0 - zm.lengthSq3(r_out_perp)[0]))) * n;
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return r_out_perp + r_out_parallel;
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}