And cones !

source/include/cone.h

@@ -0,0 +1,33 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Cone header
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#ifndef DORAYME_CONE_H
+#define DORAYME_CONE_H
+
+#include <shape.h>
+#include <ray.h>
+#include <intersect.h>
+
+class Cone : public Shape {
+protected:
+    Intersect localIntersect(Ray r);
+
+    Tuple localNormalAt(Tuple point);
+
+    bool checkCap(Ray r, double t, double y);
+    void intersectCaps(Ray r, Intersect &xs);
+
+public:
+    bool isClosed;
+    double minCap;
+    double maxCap;
+
+    Cone() : minCap(-INFINITY), maxCap(INFINITY), isClosed(false), Shape(SHAPE_CONE) {};
+};
+
+#endif /* DORAYME_CONE_H */

source/shapes/cone.cpp

@@ -0,0 +1,124 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Cone implementation
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#include <tuple.h>
+#include <ray.h>
+#include <shape.h>
+#include <cone.h>
+#include <math_helper.h>
+
+bool Cone::checkCap(Ray r, double t, double y)
+{
+    /* Helping function to reduce duplication.
+     * Checks to see if the intersection ot t is within a radius
+     * of 1 (the radius of our Cone from the y axis
+     */
+    double x = r.origin.x + t * r.direction.x;
+    double z = r.origin.z + t * r.direction.z;
+    return (x * x + z * z) <= fabs(y);
+}
+
+void Cone::intersectCaps(Ray r, Intersect &xs)
+{
+    /* Caps only mattter is the Cone is closed, and might possibly be
+     * intersected by the ray
+     */
+    if ((this->isClosed) && (fabs(r.direction.y) > getEpsilon()))
+    {
+        double t;
+        /* Check for an intersection with the lower end cap by intersecting
+         * the ray with the plan at y = this->minCap
+         */
+        t = (this->minCap - r.origin.y) / r.direction.y;
+        if (this->checkCap(r, t, this->minCap))
+        {
+            xs.add(Intersection(t, this));
+        }
+
+        /* Check for an intersection with the upper end cap by intersecting
+         * the ray with the plan at y = this->maxCap
+         */
+        t = (this->maxCap - r.origin.y) / r.direction.y;
+        if (this->checkCap(r, t, this->maxCap))
+        {
+            xs.add(Intersection(t, this));
+        }
+    }
+}
+
+Intersect Cone::localIntersect(Ray r)
+{
+    Intersect ret;
+
+    double A = pow(r.direction.x, 2) -
+               pow(r.direction.y, 2) +
+               pow(r.direction.z, 2);
+    double B = (2 * r.origin.x * r.direction.x) -
+               (2 * r.origin.y * r.direction.y) +
+               (2 * r.origin.z * r.direction.z);
+
+    double C = pow(r.origin.x, 2) -
+               pow(r.origin.y, 2) +
+               pow(r.origin.z, 2);
+
+    if ((fabs(A) <= getEpsilon()) && (fabs(B) >= getEpsilon()))
+    {
+        double t = -C / (2*B);
+        ret.add(Intersection(t, this));
+    }
+    else if (fabs(A) >= getEpsilon())
+    {
+
+        double disc = pow(B, 2) - 4 * A * C;
+
+        if (disc >= 0)
+        {
+            double t0 = (-B - sqrt(disc)) / (2 * A);
+            double t1 = (-B + sqrt(disc)) / (2 * A);
+
+            double y0 = r.origin.y + t0 * r.direction.y;
+            if ((this->minCap < y0) && (y0 < this->maxCap))
+            {
+                ret.add(Intersection(t0, this));
+            }
+
+            double y1 = r.origin.y + t1 * r.direction.y;
+            if ((this->minCap < y1) && (y1 < this->maxCap))
+            {
+                ret.add(Intersection(t1, this));
+            }
+        }
+    }
+
+    this->intersectCaps(r, ret);
+
+    return ret;
+}
+
+Tuple Cone::localNormalAt(Tuple point)
+{
+    /* Compute the square of the distance from the Y axis */
+    double dist = point.x * point.x + point.z * point.z;
+
+    if ((dist < 1) && (point.y >= (this->maxCap - getEpsilon())))
+    {
+        return Vector(0, 1, 0);
+    }
+
+    if ((dist < 1) && (point.y <= this->minCap + getEpsilon()))
+    {
+        return Vector(0, -1, 0);
+    }
+
+    double y = sqrt(point.x * point.x + point.z * point.z);
+    if (point.y > 0)
+    {
+        y = -y;
+    }
+    return Vector(point.x, y, point.z);
+}

source/tuple.cpp

@@ -19,6 +19,11 @@ double Tuple::magnitude()
 Tuple Tuple::normalise()
 {
     double mag = this->magnitude();
+    if (mag == 0)
+    {
+        return Tuple(0, 0, 0, 0);
+    }
+
     return Tuple(this->x / mag, this->y / mag, this->z / mag, this->w / mag);
 }