And now we have cylinders!

source/include/cylinder.h

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

source/include/shape.h

@@ -23,6 +23,7 @@ enum ShapeType
     SHAPE_SPHERE,
     SHAPE_PLANE,
     SHAPE_CUBE,
+    SHAPE_CYLINDER,
     SHAPE_CONE,
 };
 

source/shapes/cylinder.cpp

@@ -0,0 +1,109 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Cylinder implementation
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#include <tuple.h>
+#include <ray.h>
+#include <shape.h>
+#include <cylinder.h>
+#include <math_helper.h>
+
+bool Cylinder::checkCap(Ray r, double t)
+{
+    /* Helping function to reduce duplication.
+     * Checks to see if the intersection ot t is within a radius
+     * of 1 (the radius of our cylinder 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) <= 1;
+}
+
+void Cylinder::intersectCaps(Ray r, Intersect &xs)
+{
+    /* Caps only mattter is the cylinder 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))
+        {
+            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))
+        {
+            xs.add(Intersection(t, this));
+        }
+    }
+}
+
+Intersect Cylinder::localIntersect(Ray r)
+{
+    Intersect ret;
+
+    double A = r.direction.x * r.direction.x + r.direction.z * r.direction.z;
+
+    /* Ray is parallel to the Y axis */
+    if (A >= getEpsilon())
+    {
+        double B = 2 * r.origin.x * r.direction.x +
+                   2 * r.origin.z * r.direction.z;
+        double C = r.origin.x * r.origin.x + r.origin.z * r.origin.z - 1;
+
+        double disc = B * B - 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 Cylinder::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);
+    }
+
+    return Vector(point.x, 0, point.z);
+}