Added CUBES!

source/shapes/cube.cpp

@@ -0,0 +1,76 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Cube implementation
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#include <tuple.h>
+#include <ray.h>
+#include <shape.h>
+#include <cube.h>
+#include <math_helper.h>
+
+void Cube::checkAxis(double axeOrigin, double axeDirection, double *axeMin, double *axeMax)
+{
+    double tMinNumerator = (-1 - axeOrigin);
+    double tMaxNumerator = (1 - axeOrigin);
+
+    if (fabs(axeDirection) >= getEpsilon())
+    {
+        *axeMin = tMinNumerator / axeDirection;
+        *axeMax = tMaxNumerator / axeDirection;
+    }
+    else
+    {
+        *axeMin = tMinNumerator * INFINITY;
+        *axeMax = tMaxNumerator * INFINITY;
+    }
+
+    if (*axeMin > *axeMax)
+    {
+        double swap = *axeMax;
+        *axeMax = *axeMin;
+        *axeMin = swap;
+    }
+}
+
+Intersect Cube::localIntersect(Ray r)
+{
+    Intersect ret;
+
+    double xtMin, xtMax, ytMin, ytMax, ztMin, ztMax;
+    double tMin, tMax;
+
+    this->checkAxis(r.origin.x, r.direction.x, &xtMin, &xtMax);
+    this->checkAxis(r.origin.y, r.direction.y, &ytMin, &ytMax);
+    this->checkAxis(r.origin.z, r.direction.z, &ztMin, &ztMax);
+
+    tMin = max3(xtMin, ytMin, ztMin);
+    tMax = min3(xtMax, ytMax, ztMax);
+
+    if (tMin <= tMax)
+    {
+        ret.add(Intersection(tMin, this));
+        ret.add(Intersection(tMax, this));
+    }
+
+    return ret;
+}
+
+Tuple Cube::localNormalAt(Tuple point)
+{
+    double maxC = max3(fabs(point.x), fabs(point.y), fabs(point.z));
+
+    if (maxC == fabs(point.x))
+    {
+        return Vector(point.x, 0, 0);
+    }
+    else if (maxC == fabs(point.y))
+    {
+        return Vector(0, point.y, 0);
+    }
+
+    return Vector(0, 0, point.z);
+}