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- /*
- * DoRayMe - a quick and dirty Raytracer
- * Sphere implementation
- *
- * Created by Manoël Trapier
- * Copyright (c) 2020 986-Studio.
- *
- */
- #include <math.h>
- #include <sphere.h>
- #include <ray.h>
- #include <tuple.h>
- #include <intersect.h>
- Intersect Sphere::intersect(Ray r)
- {
- Intersect ret;
- double a, b, c, discriminant;
- Ray transRay = this->invTransform(r);
- Tuple sphere_to_ray = transRay.origin - Point(0, 0, 0);
- a = transRay.direction.dot(transRay.direction);
- b = 2 * transRay.direction.dot(sphere_to_ray);
- c = sphere_to_ray.dot(sphere_to_ray) - 1;
- discriminant = b * b - 4 * a * c;
- if (discriminant >= 0)
- {
- ret.add(Intersection((-b - sqrt(discriminant)) / (2 * a), this));
- ret.add(Intersection((-b + sqrt(discriminant)) / (2 * a), this));
- }
- return ret;
- }
- Tuple Sphere::normalAt(Tuple point)
- {
- Tuple object_point = this->inverseTransform * point;
- Tuple object_normal = (object_point - Point(0, 0, 0)).normalise();
- Tuple world_normal = this->inverseTransform.transpose() * object_normal;
- /* W may get wrong, so hack it. This is perfectly normal as we are using a 4x4 matrix instead of a 3x3 */
- world_normal.w = 0;
- return world_normal.normalise();
- }
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