Small optimization on sphere
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2 changed files with 13 additions and 6 deletions
11
main.cpp
11
main.cpp
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@ -25,14 +25,15 @@ color ray_color(const ray& r)
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double hit_sphere(const point3& center, double radius, const ray& r)
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{
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vec3 oc = r.origin - center;
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double a = dot(r.direction, r.direction);
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double b = 2.0 * dot(oc, r.direction);
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double c = dot(oc,oc) - radius*radius;
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double discriminant = b*b - 4*a*c;
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double a = r.direction.length_squared();
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double half_b = dot(oc, r.direction);
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double c = oc.length_squared() - radius*radius;
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double discriminant = half_b*half_b - a*c;
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if (discriminant < 0)
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return -1;
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else
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return (-b - sqrt(discriminant)) / (2.0*a);
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return (-half_b - sqrt(discriminant)) / a;
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}
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int main()
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