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