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implement Material as tagged union

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This commit is contained in:
Fabien Freling 2021-05-27 21:19:31 +02:00
parent bc3fb54991
commit c842fcf713
2 changed files with 53 additions and 44 deletions
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73
in_one_weekend/src/material.zig
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@ -7,13 +7,41 @@ const Ray = @import("ray.zig").Ray;
const HitRecord = @import("hittable.zig").HitRecord;
pub const MaterialType = enum {
Lambertian,
Metal,
lambertian,
metal,
};
pub const Material = struct {
materialType: MaterialType,
pub const Lambertian = struct {
color: Color,
pub fn scatter(self: Lambertian, ray: Ray, hit: HitRecord, rng: *Random) ?ScatteredRay {
var scatterDirection = hit.normal.add(vec3.random_unit_vector(rng));
// Catch degenerate scatter direction
if (scatterDirection.nearZero()) {
scatterDirection = hit.normal;
}
return ScatteredRay{
.ray = Ray{ .origin = hit.p, .direction = scatterDirection},
.color = self.color,
};
}
};
pub const Metal = struct {
color: Color,
// fuzzy: f32,
pub fn scatter(self: Metal, ray: Ray, hit: HitRecord, rng: *Random) ?ScatteredRay {
const reflected = ray.direction.unit().reflect(hit.normal);
const scattered = Ray{ .origin = hit.p, .direction = reflected };
if (scattered.direction.dot(hit.normal) <= 0) {
return null;
}
return ScatteredRay{
.ray = scattered,
.color = self.color,
};
}
};
pub const ScatteredRay = struct {
@ -21,35 +49,14 @@ pub const ScatteredRay = struct {
color: Color,
};
pub const Material = union(MaterialType) {
lambertian: Lambertian,
metal: Metal,
};
pub fn scatter(ray: Ray, hit: HitRecord, rng: *Random) ?ScatteredRay {
const scatteredDirection = switch (hit.material.materialType) {
.Lambertian => blk: {
var scatterDirection = hit.normal.add(vec3.random_unit_vector(rng));
// Catch degenerate scatter direction
if (scatterDirection.nearZero()) {
scatterDirection = hit.normal;
}
break :blk scatterDirection;
},
.Metal => blk: {
const reflected = ray.direction.unit().reflect(hit.normal);
const scattered = Ray{ .origin = hit.p, .direction = reflected };
if (scattered.direction.dot(hit.normal) <= 0) {
break :blk null;
}
break :blk scattered.direction;
},
return switch (hit.material) {
.lambertian => |m| m.scatter(ray, hit, rng),
.metal => |m| m.scatter(ray, hit, rng),
};
if (scatteredDirection) |dir| {
return ScatteredRay{
.ray = Ray{ .origin = hit.p, .direction = dir},
.color = hit.material.color,
};
}
return null;
}