Phireh/cpp-raytracer
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Small optimization on sphere

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This commit is contained in:
David 2021-08-20 23:43:44 +02:00
commit 3aea707982
2 changed files with 13 additions and 6 deletions
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11
main.cpp
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@ -25,14 +25,15 @@ color ray_color(const ray& r)
double hit_sphere(const point3& center, double radius, const ray& r) double hit_sphere(const point3& center, double radius, const ray& r)
{ {
vec3 oc = r.origin - center; vec3 oc = r.origin - center;
double a = dot(r.direction, r.direction); double a = r.direction.length_squared();
double b = 2.0 * dot(oc, r.direction); double half_b = dot(oc, r.direction);
double c = dot(oc,oc) - radius*radius; double c = oc.length_squared() - radius*radius;
double discriminant = b*b - 4*a*c; double discriminant = half_b*half_b - a*c;
if (discriminant < 0) if (discriminant < 0)
return -1; return -1;
else else
return (-b - sqrt(discriminant)) / (2.0*a); return (-half_b - sqrt(discriminant)) / a;
} }
int main() int main()

8
vec3.hpp
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@ -58,7 +58,13 @@ struct vec3 {
double length() const double length() const
{ {
return sqrt(x*x + y*y + z*z); return sqrt(x*x + y*y + z*z);
} }
// Length squared, useful for some calculations
double length_squared() const
{
return x*x + y*y + z*z;
}
}; };
/* Type aliases */ /* Type aliases */