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Merge pull request #1617 from RayTracing/refactor/rotate-y-hit
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Small improvement to rotate_y::hit() function
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@hollasch
hollasch authored Aug 23, 2024
2 parents c6f803f + 07f11f5 commit b09c5a1
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Showing 4 changed files with 76 additions and 54 deletions.
1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -11,6 +11,7 @@ Change Log / Ray Tracing in One Weekend
- Fix -- Big improvement to print version listing font size (#1595) and more compact line
height for code listings in both print and browser.
- Change -- Include hittable.h from material.h; drop `hit_record` forward declaration (#1609)
- Fix -- Slight improvement to `rotate_y::hit()` function (#1484)
- Fix -- Fixed possible bogus values from `random_unit_vector()` due to underflow (#1606)

### In One Weekend
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43 changes: 25 additions & 18 deletions books/RayTracingTheNextWeek.html
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Expand Up @@ -3816,34 +3816,41 @@
public:

bool hit(const ray& r, interval ray_t, hit_record& rec) const override {
// Change the ray from world space to object space
auto origin = r.origin();
auto direction = r.direction();

origin[0] = cos_theta*r.origin()[0] - sin_theta*r.origin()[2];
origin[2] = sin_theta*r.origin()[0] + cos_theta*r.origin()[2];
// Transform the ray from world space to object space.

direction[0] = cos_theta*r.direction()[0] - sin_theta*r.direction()[2];
direction[2] = sin_theta*r.direction()[0] + cos_theta*r.direction()[2];
auto origin = point3(
(cos_theta * r.origin().x()) - (sin_theta * r.origin().z()),
r.origin().y(),
(sin_theta * r.origin().x()) + (cos_theta * r.origin().z())
);

auto direction = vec3(
(cos_theta * r.direction().x()) - (sin_theta * r.direction().z()),
r.direction().y(),
(sin_theta * r.direction().x()) + (cos_theta * r.direction().z())
);

ray rotated_r(origin, direction, r.time());

// Determine whether an intersection exists in object space (and if so, where)
// Determine whether an intersection exists in object space (and if so, where).

if (!object->hit(rotated_r, ray_t, rec))
return false;

// Change the intersection point from object space to world space
auto p = rec.p;
p[0] = cos_theta*rec.p[0] + sin_theta*rec.p[2];
p[2] = -sin_theta*rec.p[0] + cos_theta*rec.p[2];
// Transform the intersection from object space back to world space.

// Change the normal from object space to world space
auto normal = rec.normal;
normal[0] = cos_theta*rec.normal[0] + sin_theta*rec.normal[2];
normal[2] = -sin_theta*rec.normal[0] + cos_theta*rec.normal[2];
rec.p = point3(
(cos_theta * rec.p.x()) + (sin_theta * rec.p.z()),
rec.p.y(),
(-sin_theta * rec.p.x()) + (cos_theta * rec.p.z())
);

rec.p = p;
rec.normal = normal;
rec.normal = vec3(
(cos_theta * rec.normal.x()) + (sin_theta * rec.normal.z()),
rec.normal.y(),
(-sin_theta * rec.normal.x()) + (cos_theta * rec.normal.z())
);

return true;
}
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43 changes: 25 additions & 18 deletions src/TheNextWeek/hittable.h
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Expand Up @@ -115,34 +115,41 @@ class rotate_y : public hittable {
}

bool hit(const ray& r, interval ray_t, hit_record& rec) const override {
// Change the ray from world space to object space
auto origin = r.origin();
auto direction = r.direction();

origin[0] = cos_theta*r.origin()[0] - sin_theta*r.origin()[2];
origin[2] = sin_theta*r.origin()[0] + cos_theta*r.origin()[2];
// Transform the ray from world space to object space.

direction[0] = cos_theta*r.direction()[0] - sin_theta*r.direction()[2];
direction[2] = sin_theta*r.direction()[0] + cos_theta*r.direction()[2];
auto origin = point3(
(cos_theta * r.origin().x()) - (sin_theta * r.origin().z()),
r.origin().y(),
(sin_theta * r.origin().x()) + (cos_theta * r.origin().z())
);

auto direction = vec3(
(cos_theta * r.direction().x()) - (sin_theta * r.direction().z()),
r.direction().y(),
(sin_theta * r.direction().x()) + (cos_theta * r.direction().z())
);

ray rotated_r(origin, direction, r.time());

// Determine whether an intersection exists in object space (and if so, where)
// Determine whether an intersection exists in object space (and if so, where).

if (!object->hit(rotated_r, ray_t, rec))
return false;

// Change the intersection point from object space to world space
auto p = rec.p;
p[0] = cos_theta*rec.p[0] + sin_theta*rec.p[2];
p[2] = -sin_theta*rec.p[0] + cos_theta*rec.p[2];
// Transform the intersection from object space back to world space.

// Change the normal from object space to world space
auto normal = rec.normal;
normal[0] = cos_theta*rec.normal[0] + sin_theta*rec.normal[2];
normal[2] = -sin_theta*rec.normal[0] + cos_theta*rec.normal[2];
rec.p = point3(
(cos_theta * rec.p.x()) + (sin_theta * rec.p.z()),
rec.p.y(),
(-sin_theta * rec.p.x()) + (cos_theta * rec.p.z())
);

rec.p = p;
rec.normal = normal;
rec.normal = vec3(
(cos_theta * rec.normal.x()) + (sin_theta * rec.normal.z()),
rec.normal.y(),
(-sin_theta * rec.normal.x()) + (cos_theta * rec.normal.z())
);

return true;
}
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43 changes: 25 additions & 18 deletions src/TheRestOfYourLife/hittable.h
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Expand Up @@ -123,34 +123,41 @@ class rotate_y : public hittable {
}

bool hit(const ray& r, interval ray_t, hit_record& rec) const override {
// Change the ray from world space to object space
auto origin = r.origin();
auto direction = r.direction();

origin[0] = cos_theta*r.origin()[0] - sin_theta*r.origin()[2];
origin[2] = sin_theta*r.origin()[0] + cos_theta*r.origin()[2];
// Transform the ray from world space to object space.

direction[0] = cos_theta*r.direction()[0] - sin_theta*r.direction()[2];
direction[2] = sin_theta*r.direction()[0] + cos_theta*r.direction()[2];
auto origin = point3(
(cos_theta * r.origin().x()) - (sin_theta * r.origin().z()),
r.origin().y(),
(sin_theta * r.origin().x()) + (cos_theta * r.origin().z())
);

auto direction = vec3(
(cos_theta * r.direction().x()) - (sin_theta * r.direction().z()),
r.direction().y(),
(sin_theta * r.direction().x()) + (cos_theta * r.direction().z())
);

ray rotated_r(origin, direction, r.time());

// Determine whether an intersection exists in object space (and if so, where)
// Determine whether an intersection exists in object space (and if so, where).

if (!object->hit(rotated_r, ray_t, rec))
return false;

// Change the intersection point from object space to world space
auto p = rec.p;
p[0] = cos_theta*rec.p[0] + sin_theta*rec.p[2];
p[2] = -sin_theta*rec.p[0] + cos_theta*rec.p[2];
// Transform the intersection from object space back to world space.

// Change the normal from object space to world space
auto normal = rec.normal;
normal[0] = cos_theta*rec.normal[0] + sin_theta*rec.normal[2];
normal[2] = -sin_theta*rec.normal[0] + cos_theta*rec.normal[2];
rec.p = point3(
(cos_theta * rec.p.x()) + (sin_theta * rec.p.z()),
rec.p.y(),
(-sin_theta * rec.p.x()) + (cos_theta * rec.p.z())
);

rec.p = p;
rec.normal = normal;
rec.normal = vec3(
(cos_theta * rec.normal.x()) + (sin_theta * rec.normal.z()),
rec.normal.y(),
(-sin_theta * rec.normal.x()) + (cos_theta * rec.normal.z())
);

return true;
}
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