Huge speed up by changing how Intersect are shared.

source/include/cone.h

@@ -17,7 +17,7 @@
 
 class Cone : public Shape {
 protected:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
 
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 

source/include/csg.h

@@ -28,7 +28,7 @@ protected:
     BoundingBox bounds;
 
 protected:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
     BoundingBox getLocalBounds();
 
@@ -42,7 +42,7 @@ protected:
 public:
     CSG(OperationType operation, Shape *left, Shape *right);
 
-    Intersect intersect(Ray r);
+    void intersect(Ray &r, Intersect &xs);
 
     bool includes(Shape *b);
 

source/include/cube.h

@@ -19,7 +19,7 @@ class Cube : public Shape {
 protected:
     void checkAxis(double axeOrigin, double axeDirection, double *axeMin, double *axeMax);
 
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
 
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 

source/include/cylinder.h

@@ -18,7 +18,7 @@
 class Cylinder : public Shape {
 
 protected:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
 
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 

source/include/group.h

@@ -28,7 +28,7 @@ private:
     char name[32 + 1];
 
 protected:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 
     BoundingBox bounds;
@@ -43,7 +43,7 @@ public:
     Shape *getObject(const int p) { return this->objectList[p]; };
     Shape *getUnboxable(const int p) { return this->unboxableObjectList[p]; };
 
-    Intersect intersect(Ray r);
+    void intersect(Ray &r, Intersect &xs);
     BoundingBox getLocalBounds();
     BoundingBox getBounds();
 
@@ -59,6 +59,8 @@ public:
 
     void lock();
 
+    void setBounds(BoundingBox &bb) { this->bounds | bb; };
+
     const char *getName() { return this->name; };
 
     void dumpMe(FILE * fp);

source/include/objfile.h

@@ -31,7 +31,7 @@ private:
     uint32_t vertexNormalCount;
 
 private:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 
 public:
@@ -59,7 +59,7 @@ public:
     Point vertices(uint32_t i) { return *this->vertexList[i - 1]; };
     Vector verticesNormal(uint32_t i) { return *this->vertexNormalList[i - 1]; };
     Group *groups(const char *groupName);
-    Intersect intersect(Ray r);
+    void intersect(Ray &r, Intersect &xs);
     BoundingBox getLocalBounds();
     BoundingBox getBounds();
 

source/include/plane.h

@@ -14,7 +14,7 @@
 class Plane : public Shape
 {
 protected:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 
 public:

source/include/shape.h

@@ -44,7 +44,7 @@ protected:
     bool locked;
 
 protected:
-    virtual Intersect localIntersect(Ray r) = 0;
+    virtual void localIntersect(Ray r, Intersect &xs) = 0;
     virtual Tuple localNormalAt(Tuple point, Intersection *hit) = 0;
 
 public:
@@ -62,7 +62,7 @@ public:
 
     ShapeType getType() { return this->type; };
 
-    virtual Intersect intersect(Ray r);
+    virtual void intersect(Ray &r, Intersect &xs);
     Tuple normalAt(Tuple point, Intersection *hit = nullptr);
 
     /* Bounding box points are always world value */
@@ -92,8 +92,8 @@ public:
 
     void setTransform(Matrix transform);
     void setMaterial(Material material) { this->material = material; this->materialSet = true; };
-    Ray transform(Ray r) { return Ray(this->transformMatrix * r.origin, this->transformMatrix * r.direction); };
-    Ray invTransform(Ray r) { return Ray(this->inverseTransform * r.origin, this->inverseTransform * r.direction); };
+    Ray transform(Ray &r) { return Ray(this->transformMatrix * r.origin, this->transformMatrix * r.direction); };
+    Ray invTransform(Ray &r) { return Ray(this->inverseTransform * r.origin, this->inverseTransform * r.direction); };
 
     bool operator==(const Shape &b) const { return this->material == b.material &&
                                                    this->type == b.type &&

source/include/sphere.h

@@ -18,7 +18,7 @@
 class Sphere : public Shape
 {
 protected:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 
 public:

source/include/testshape.h

@@ -16,7 +16,7 @@
 class TestShape : public Shape
 {
 private:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 
 public:

source/include/triangle.h

@@ -15,7 +15,7 @@
 class Triangle : public Shape
 {
 protected:
-    Intersect localIntersect(Ray r);
+    void localIntersect(Ray r, Intersect &xs);
     Tuple localNormalAt(Tuple point, Intersection *hit = nullptr);
 
 public:

source/include/world.h

@@ -63,7 +63,7 @@ public:
     Colour reflectColour(Computation comps, uint32_t depthCount = 4);
     Colour refractedColour(Computation comps, uint32_t depthCount = 4);
 
-    Intersect intersect(Ray r);
+    void intersect(Ray &r, Intersect &xs);
 
     void finalise(WorldOptimiser &opt);
 

source/shapes/cone.cpp

@@ -51,10 +51,8 @@ void Cone::intersectCaps(Ray r, Intersect &xs)
     }
 }
 
-Intersect Cone::localIntersect(Ray r)
+void Cone::localIntersect(Ray r, Intersect &xs)
 {
-    Intersect ret;
-
     double A = (r.direction.x * r.direction.x) -
                (r.direction.y * r.direction.y) +
                (r.direction.z * r.direction.z);
@@ -70,7 +68,7 @@ Intersect Cone::localIntersect(Ray r)
     if ((fabs(A) <= getEpsilon()) && (fabs(B) >= getEpsilon()))
     {
         double t = -C / (2*B);
-        ret.add(Intersection(t, this));
+        xs.add(Intersection(t, this));
     }
     else if (fabs(A) >= getEpsilon())
     {
@@ -83,20 +81,18 @@ Intersect Cone::localIntersect(Ray r)
             double y0 = r.origin.y + t0 * r.direction.y;
             if ((this->minCap < y0) && (y0 < this->maxCap))
             {
-                ret.add(Intersection(t0, this));
+                xs.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));
+                xs.add(Intersection(t1, this));
             }
         }
     }
 
-    this->intersectCaps(r, ret);
-
-    return ret;
+    this->intersectCaps(r, xs);
 }
 
 Tuple Cone::localNormalAt(Tuple point, Intersection *hit)

source/shapes/csg.cpp

@@ -24,31 +24,24 @@ CSG::CSG(OperationType operation, Shape *left, Shape *right) : Shape(Shape::CSG)
     this->bounds | this->right->getBounds();
 }
 
-Intersect CSG::localIntersect(Ray r)
+void CSG::localIntersect(Ray r, Intersect &xs)
 {
-    return this->intersect(r);
+    this->intersect(r, xs);
 }
 
 
-Intersect CSG::intersect(Ray r)
+void CSG::intersect(Ray &r, Intersect &xs)
 {
     int i;
-    Intersect ret = Intersect();
+    Intersect tmp = Intersect();
 
     if (this->bounds.intesectMe(r))
     {
-        Intersect leftxs = this->left->intersect(r);
-        Intersect rightxs = this->right->intersect(r);
+        this->left->intersect(r, tmp);
+        this->right->intersect(r, tmp);
 
-        for (i = 0 ; i < rightxs.count() ; i++)
-        {
-            leftxs.add(rightxs[i]);
+        this->filterIntersections(tmp, xs);
     }
-
-        this->filterIntersections(leftxs, ret);
-    }
-
-    return ret;
 }
 
 Tuple CSG::localNormalAt(Tuple point, Intersection *hit)

source/shapes/cube.cpp

@@ -36,10 +36,8 @@ void Cube::checkAxis(double axeOrigin, double axeDirection, double *axeMin, doub
     }
 }
 
-Intersect Cube::localIntersect(Ray r)
+void Cube::localIntersect(Ray r, Intersect &xs)
 {
-    Intersect ret;
-
     double xtMin, xtMax, ytMin, ytMax, ztMin, ztMax;
     double tMin, tMax;
 
@@ -52,11 +50,9 @@ Intersect Cube::localIntersect(Ray r)
 
     if (tMin <= tMax)
     {
-        ret.add(Intersection(tMin, this));
-        ret.add(Intersection(tMax, this));
+        xs.add(Intersection(tMin, this));
+        xs.add(Intersection(tMax, this));
     }
-
-    return ret;
 }
 
 Tuple Cube::localNormalAt(Tuple point, Intersection *hit)

source/shapes/cylinder.cpp

@@ -51,10 +51,8 @@ void Cylinder::intersectCaps(Ray r, Intersect &xs)
     }
 }
 
-Intersect Cylinder::localIntersect(Ray r)
+void Cylinder::localIntersect(Ray r, Intersect &xs)
 {
-    Intersect ret;
-
     double A = r.direction.x * r.direction.x + r.direction.z * r.direction.z;
 
     /* Ray is parallel to the Y axis */
@@ -74,20 +72,18 @@ Intersect Cylinder::localIntersect(Ray r)
             double y0 = r.origin.y + t0 * r.direction.y;
             if ((this->minCap < y0) && (y0 < this->maxCap))
             {
-                ret.add(Intersection(t0, this));
+                xs.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));
+                xs.add(Intersection(t1, this));
             }
         }
     }
 
-    this->intersectCaps(r, ret);
-
-    return ret;
+    this->intersectCaps(r, xs);
 }
 
 Tuple Cylinder::localNormalAt(Tuple point, Intersection *hit)

source/shapes/group.cpp

@@ -36,9 +36,8 @@ Group::Group(const char *name) : Shape(Shape::GROUP)
     }
 }
 
-Intersect Group::intersect(Ray r)
+void Group::intersect(Ray &r, Intersect &xs)
 {
-    Intersect ret;
     int i, j;
     if (this->objectCount > 0)
     {
@@ -46,14 +45,7 @@ Intersect Group::intersect(Ray r)
         {
             for (i = 0 ; i < this->objectCount ; i++)
             {
-                Intersect xs = this->objectList[i]->intersect(r);
-                if (xs.count() > 0)
-                {
-                    for (j = 0 ; j < xs.count() ; j++)
-                    {
-                        ret.add(xs[j]);
-                    }
-                }
+                this->objectList[i]->intersect(r, xs);
             }
         }
     }
@@ -63,18 +55,10 @@ Intersect Group::intersect(Ray r)
     {
         for(i = 0; i < this->unboxableObjectCount; i++)
         {
-            Intersect xs = this->unboxableObjectList[i]->intersect(r);
-            if (xs.count() > 0)
-            {
-                for(j = 0; j < xs.count(); j++)
-                {
-                    ret.add(xs[j]);
+            this->unboxableObjectList[i]->intersect(r, xs);
         }
     }
 }
-    }
-    return ret;
-}
 
 bool Group::includes(Shape *b)
 {
@@ -104,9 +88,9 @@ bool Group::includes(Shape *b)
     return false;
 }
 
-Intersect Group::localIntersect(Ray r)
+void Group::localIntersect(Ray r, Intersect &xs)
 {
-    return Intersect();
+    this->intersect(r, xs);
 }
 
 Tuple Group::localNormalAt(Tuple point, Intersection *hit)

source/shapes/objfile.cpp

@@ -160,9 +160,9 @@ Group *OBJFile::groups(const char *groupName)
     return nullptr;
 }
 
-Intersect OBJFile::intersect(Ray r)
+void OBJFile::intersect(Ray &r, Intersect &xs)
 {
-    return this->baseGroup->intersect(r);
+    this->baseGroup->intersect(r, xs);
 }
 
 bool OBJFile::includes(Shape *b)
@@ -170,9 +170,9 @@ bool OBJFile::includes(Shape *b)
     return this->baseGroup->includes(b);
 }
 
-Intersect OBJFile::localIntersect(Ray r)
+void OBJFile::localIntersect(Ray r, Intersect &xs)
 {
-    return Intersect();
+    this->intersect(r, xs);
 }
 
 Tuple OBJFile::localNormalAt(Tuple point, Intersection *hit)

source/shapes/plane.cpp

@@ -12,22 +12,20 @@
 #include <plane.h>
 #include <math_helper.h>
 
-Intersect Plane::localIntersect(Ray r)
+void Plane::localIntersect(Ray r, Intersect &xs)
 {
     double t;
-    Intersect ret = Intersect();
 
     if (fabs(r.direction.y) < getEpsilon())
     {
         /* With a direction == 0, the ray can't intersect the plane */
-        return ret;
     }
-
+    else
+    {
         t = -r.origin.y / r.direction.y;
 
-    ret.add(Intersection(t, this));
-
-    return ret;
+        xs.add(Intersection(t, this));
+    }
 }
 
 Tuple Plane::localNormalAt(Tuple point, Intersection *hit)

source/shapes/shape.cpp

@@ -25,9 +25,9 @@ Shape::Shape(ShapeType type)
     this->updateTransform();
 }
 
-Intersect Shape::intersect(Ray r)
+void Shape::intersect(Ray &r, Intersect &xs)
 {
-    return this->localIntersect(this->invTransform(r));
+    this->localIntersect(this->invTransform(r), xs);
 };
 
 Tuple Shape::normalToWorld(Tuple normalVector)

source/shapes/sphere.cpp

@@ -13,9 +13,8 @@
 #include <tuple.h>
 #include <intersect.h>
 
-Intersect Sphere::localIntersect(Ray r)
+void Sphere::localIntersect(Ray r, Intersect &xs)
 {
-    Intersect ret;
     double a, b, c, discriminant;
 
     Tuple sphere_to_ray = r.origin - Point(0, 0, 0);
@@ -28,11 +27,9 @@ Intersect Sphere::localIntersect(Ray r)
 
     if (discriminant >= 0)
     {
-        ret.add(Intersection((-b - sqrt(discriminant)) / (2 * a), this));
-        ret.add(Intersection((-b + sqrt(discriminant)) / (2 * a), this));
+        xs.add(Intersection((-b - sqrt(discriminant)) / (2 * a), this));
+        xs.add(Intersection((-b + sqrt(discriminant)) / (2 * a), this));
     }
-
-    return ret;
 }
 
 Tuple Sphere::localNormalAt(Tuple point, Intersection *hit)

source/shapes/testshape.cpp

@@ -13,10 +13,9 @@ TestShape::TestShape() : localRay(Point(0, 0, 0), Vector(0, 0, 0))
 {
 }
 
-Intersect TestShape::localIntersect(Ray r)
+void TestShape::localIntersect(Ray r, Intersect &xs)
 {
     this->localRay = r;
-    return Intersect();
 }
 
 Tuple TestShape::localNormalAt(Tuple point, Intersection *hit)

source/shapes/triangle.cpp

@@ -21,15 +21,13 @@ Triangle::Triangle(Point p1, Point p2, Point p3) : Shape(Shape::TRIANGLE), p1(p1
     this->normal = e2.cross(e1).normalise();
 }
 
-Intersect Triangle::localIntersect(Ray r)
+void Triangle::localIntersect(Ray r, Intersect &xs)
 {
-    Intersect ret;
-
     Tuple dirCrossE2 = r.direction.cross(this->e2);
     double determinant = this->e1.dot(dirCrossE2);
     if (fabs(determinant) < getEpsilon())
     {
-        return ret;
+        return;
     }
 
     double f = 1.0 / determinant;
@@ -40,18 +38,16 @@ Intersect Triangle::localIntersect(Ray r)
 
     if ((u < 0) || (u > 1))
     {
-        return ret;
+        return;
     }
 
     if ((v < 0) || ((u + v) > 1))
     {
-        return ret;
+        return;
     }
 
     double t = f * this->e2.dot(originCrossE1);
-    ret.add(Intersection(t, this, u, v));
-
-    return ret;
+    xs.add(Intersection(t, this, u, v));
 }
 
 Tuple Triangle::localNormalAt(Tuple point, Intersection *hit)

source/world.cpp

@@ -75,9 +75,9 @@ bool World::objectIsIn(Shape &s)
     return this->worldGroup.includes(&s);
 }
 
-Intersect World::intersect(Ray r)
+void World::intersect(Ray &r, Intersect &xs)
 {
-    return this->worldGroup.intersect(r);
+    this->worldGroup.intersect(r, xs);
 }
 
 Tuple World::shadeHit(Computation comps, uint32_t depthCount)
@@ -108,7 +108,8 @@ Tuple World::shadeHit(Computation comps, uint32_t depthCount)
 
 Tuple World::colourAt(Ray r, uint32_t depthCount)
 {
-    Intersect allHits = this->intersect(r);
+    Intersect allHits;
+    this->intersect(r, allHits);
     Intersection hit = allHits.hit();
 
     stats.setMaxDepth(depthCount);
@@ -131,7 +132,8 @@ bool World::isShadowed(Tuple point, Tuple lightPosition)
 
     Ray r = Ray(point, direction);
     stats.addLightRay();
-    Intersect xs = this->intersect(r);
+    Intersect xs;
+    this->intersect(r, xs);
 
     int i;
     for(i = 0; i < xs.count(); i++)

tests/ch5_test.cpp

@@ -32,7 +32,8 @@ int main()
             double worldX = -(wallSize / 2) + pixelSize * x;
             Point position = Point(worldX, worldY, wallDistance);
             Ray r = Ray(cameraOrigin, (position - cameraOrigin).normalise());
-            Intersect xs = s.intersect(r);
+            Intersect xs;
+            s.intersect(r, xs);
 
             if (!xs.hit().nothing())
             {

tests/ch6_test.cpp

@@ -36,7 +36,8 @@ int main()
             double worldX = -(wallSize / 2) + pixelSize * x;
             Point position = Point(worldX, worldY, wallDistance);
             Ray r = Ray(cameraOrigin, (position - cameraOrigin).normalise());
-            Intersect xs = s.intersect(r);
+            Intersect xs;
+            s.intersect(r, xs);
 
             Intersection hit = xs.hit();
 

tests/cone_test.cpp

@@ -46,7 +46,7 @@ TEST(ConeTest, Intersecting_a_cone_with_a_ray)
         Tuple direction = Directions[i].normalise();
         Ray r = Ray(Origins[i], direction);
 
-        Intersect xs = cone.intersect(r);
+        Intersect xs; cone.intersect(r, xs);
 
         /* Temporary lower the precision */
         set_equal_precision(0.00001);
@@ -64,7 +64,7 @@ TEST(ConeTest, Intersecting_a_cone_with_a_ray_parall_to_one_of_its_halves)
     Cone cone = Cone();
     Tuple direction = Vector(0, 1, 1).normalise();
     Ray r = Ray(Point(0, 0, -1), direction);
-    Intersect xs = cone.intersect(r);
+    Intersect xs; cone.intersect(r, xs);
     ASSERT_EQ(xs.count(), 1);
 
     /* Temporary lower the precision */
@@ -102,7 +102,8 @@ TEST(ConeTest, Intersecting_a_cone_end_cap)
         Tuple direction = Directions[i].normalise();
         Ray r = Ray(Origins[i], direction);
 
-        Intersect xs = cone.intersect(r);
+        Intersect xs;
+        cone.intersect(r, xs);
 
         ASSERT_EQ(xs.count(), Counts[i]);
     }

tests/csg_test.cpp

@@ -18,8 +18,8 @@
 class CSGTest : public CSG
 {
 public:
-    Intersect doLocalIntersect(Ray r) {
-        return this->localIntersect(r);
+    void doLocalIntersect(Ray r, Intersect &xs) {
+        return this->localIntersect(r, xs);
     };
     Tuple doLocalNormalAt(Tuple point, Intersection *hit = nullptr) {
         return this->localNormalAt(point, hit);
@@ -202,7 +202,7 @@ TEST(CSGTest, A_ray_misses_a_csg_object)
     CSGTest c = CSGTest(CSG::UNION, &s1, &s2);
 
     Ray r = Ray(Point(0, 2, -5), Vector(0, 0, 1));
-    Intersect xs = c.doLocalIntersect(r);
+    Intersect xs; c.doLocalIntersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -217,7 +217,7 @@ TEST(CSGTest, A_ray_hits_a_csg_object)
     CSGTest c = CSGTest(CSG::UNION, &s1, &s2);
 
     Ray r = Ray(Point(0, 0, -5), Vector(0, 0, 1));
-    Intersect xs = c.doLocalIntersect(r);
+    Intersect xs; c.doLocalIntersect(r, xs);
 
     ASSERT_EQ(xs.count(), 2);
     ASSERT_TRUE(double_equal(xs[0].t, 4));

tests/cube_test.cpp

@@ -43,7 +43,7 @@ TEST(CubeTest, A_ray_intersects_a_cube)
     for(i = 0; i < 7; i++)
     {
         Ray r = Ray(Origins[i], Directions[i]);
-        Intersect xs = c.intersect(r);
+        Intersect xs; c.intersect(r, xs);
 
         ASSERT_EQ(xs.count(), 2);
         EXPECT_EQ(xs[0].t, t1[i]);
@@ -77,7 +77,7 @@ TEST(CubeTest, A_ray_miss_a_cube)
     for(i = 0; i < 6; i++)
     {
         Ray r = Ray(Origins[i], Directions[i]);
-        Intersect xs = c.intersect(r);
+        Intersect xs; c.intersect(r, xs);
 
         ASSERT_EQ(xs.count(), 0);
     }

tests/cylinder_test.cpp

@@ -34,7 +34,7 @@ TEST(CylinderTest, A_ray_miss_a_cylinder)
         Tuple direction = Directions[i].normalise();
         Ray r = Ray(Origins[i], direction);
 
-        Intersect xs = cyl.intersect(r);
+        Intersect xs; cyl.intersect(r, xs);
 
         ASSERT_EQ(xs.count(), 0);
     }
@@ -65,7 +65,7 @@ TEST(CylinderTest, A_ray_hit_a_cylinder)
         Tuple direction = Directions[i].normalise();
         Ray r = Ray(Origins[i], direction);
 
-        Intersect xs = cyl.intersect(r);
+        Intersect xs; cyl.intersect(r, xs);
 
         /* Temporary lower the precision */
         set_equal_precision(0.00001);
@@ -142,7 +142,7 @@ TEST(CylinderTest, Intersecting_a_constrained_cylinder)
         Tuple direction = Directions[i].normalise();
         Ray r = Ray(Origins[i], direction);
 
-        Intersect xs = cyl.intersect(r);
+        Intersect xs; cyl.intersect(r, xs);
 
         ASSERT_EQ(xs.count(), Counts[i]);
     }
@@ -184,7 +184,7 @@ TEST(CylinderTest, Intersecting_the_caps_of_a_close_cylinder)
         Tuple direction = Directions[i].normalise();
         Ray r = Ray(Origins[i], direction);
 
-        Intersect xs = cyl.intersect(r);
+        Intersect xs; cyl.intersect(r, xs);
         ASSERT_EQ(xs.count(), Counts[i]);
     }
 }

tests/group_test.cpp

@@ -39,7 +39,7 @@ TEST(GroupTest, Intersecting_a_ray_with_an_empty_group)
 {
     Group g = Group();
     Ray r = Ray(Point(0, 0, 0), Vector(0, 0, 1));
-    Intersect xs = g.intersect(r);
+    Intersect xs; g.intersect(r, xs);
     ASSERT_EQ(xs.count(), 0);
 }
 
@@ -58,7 +58,7 @@ TEST(GroupTest, Intersecting_a_ray_with_an_nonempty_group)
     g.addObject(&s3);
 
     Ray r = Ray(Point(0, 0, -5), Vector(0, 0, 1));
-    Intersect xs = g.intersect(r);
+    Intersect xs; g.intersect(r, xs);
     ASSERT_EQ(xs.count(), 4);
     EXPECT_EQ(xs[0].object, &s2);
     EXPECT_EQ(xs[1].object, &s2);
@@ -77,7 +77,7 @@ TEST(GroupTest, Intersecting_a_transformed_group)
     g.addObject(&s);
 
     Ray r = Ray(Point(10, 0, -50), Vector(0, 0, 1));
-    Intersect xs = g.intersect(r);
+    Intersect xs; g.intersect(r, xs);
     ASSERT_EQ(xs.count(), 2);
 }
 

tests/intersect_test.cpp

@@ -57,7 +57,7 @@ TEST(IntersectTest, Intersect_sets_the_object_on_the_intersection)
 {
     Ray r = Ray(Point(0, 0, -5), Vector(0, 0, 1));
     Sphere s = Sphere();
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 2);
     ASSERT_EQ(xs[0].object, (Shape *)&s);

tests/plane_test.cpp

@@ -31,7 +31,7 @@ TEST(PlaneTest, Intersect_with_a_ray_parallel_to_the_plane)
     Plane p = Plane();
     Ray r = Ray(Point(0, 10, 0), Vector(0, 0, 1));
 
-    Intersect xs = p.intersect(r);
+    Intersect xs; p.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -41,7 +41,7 @@ TEST(PlaneTest, Intersect_with_a_coplanar_ray)
     Plane p = Plane();
     Ray r = Ray(Point(0, 0, 0), Vector(0, 0, 1));
 
-    Intersect xs = p.intersect(r);
+    Intersect xs; p.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -51,7 +51,7 @@ TEST(PlaneTest, A_ray_intersecting_a_plane_from_above)
     Plane p = Plane();
     Ray r = Ray(Point(0, 1, 0), Vector(0, -1, 0));
 
-    Intersect xs = p.intersect(r);
+    Intersect xs; p.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 1);
     ASSERT_EQ(xs[0].t, 1);
@@ -63,7 +63,7 @@ TEST(PlaneTest, A_ray_intersecting_a_plane_from_below)
     Plane p = Plane();
     Ray r = Ray(Point(0, -1, 0), Vector(0, 1, 0));
 
-    Intersect xs = p.intersect(r);
+    Intersect xs; p.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 1);
     ASSERT_EQ(xs[0].t, 1);

tests/shape_test.cpp

@@ -53,7 +53,7 @@ TEST(ShapeTest, Intersecting_a_scaled_shape_with_a_ray)
     TestShape s = TestShape();
 
     s.setTransform(scaling(2, 2, 2));
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(s.localRay.origin, Point(0, 0, -2.5));
     ASSERT_EQ(s.localRay.direction, Vector(0, 0, 0.5));
@@ -65,7 +65,7 @@ TEST(ShapeTest, Intersecting_a_translated_shape_with_a_ray)
     TestShape s = TestShape();
 
     s.setTransform(translation(5, 0, 0));
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(s.localRay.origin, Point(-5, 0, -5));
     ASSERT_EQ(s.localRay.direction, Vector(0, 0, 1));

tests/smoothtriangle_test.cpp

@@ -14,9 +14,9 @@ class SmoothTriTest : public SmoothTriangle
 {
 public:
     SmoothTriTest(Point p1, Point p2, Point p3, Vector n1, Vector n2, Vector n3) : SmoothTriangle(p1, p2, p3, n1, n2, n3) {};
-    Intersect doLocalIntersect(Ray ray)
+    void doLocalIntersect(Ray ray, Intersect &xs)
     {
-        return this->localIntersect(ray);
+        this->localIntersect(ray, xs);
     };
 
     Tuple doLocalNormalAt(Tuple point, Intersection *hit)
@@ -48,7 +48,7 @@ TEST(SmoothTriangleTest, An_intersection_with_a_smooth_triangle_stores_u_v)
 {
     Ray r = Ray(Point(-0.2, 0.3, -2), Vector(0, 0, 1));
 
-    Intersect xs = tri.doLocalIntersect(r);
+    Intersect xs; tri.doLocalIntersect(r, xs);
 
     ASSERT_TRUE(double_equal(xs[0].u, 0.45));
     ASSERT_TRUE(double_equal(xs[0].v, 0.25));

tests/sphere_test.cpp

@@ -17,7 +17,7 @@ TEST(SphereTest, A_ray_intersect_a_sphere_at_two_points)
 {
     Ray r = Ray(Point(0, 0, -5), Vector(0, 0, 1));
     Sphere s = Sphere();
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 2);
     ASSERT_EQ(xs[0].t, 4.0);
@@ -28,7 +28,7 @@ TEST(SphereTest, A_ray_intersect_a_sphere_at_a_tangent)
 {
     Ray r = Ray(Point(0, 1, -5), Vector(0, 0, 1));
     Sphere s = Sphere();
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 2);
     ASSERT_EQ(xs[0].t, 5.0);
@@ -39,7 +39,7 @@ TEST(SphereTest, A_ray_miss_a_sphere)
 {
     Ray r = Ray(Point(0, 2, -5), Vector(0, 0, 1));
     Sphere s = Sphere();
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -48,7 +48,7 @@ TEST(SphereTest, A_ray_originate_inside_a_sphere)
 {
     Ray r = Ray(Point(0, 0, 0), Vector(0, 0, 1));
     Sphere s = Sphere();
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 2);
     ASSERT_EQ(xs[0].t, -1.0);
@@ -59,7 +59,7 @@ TEST(SphereTest, A_sphere_is_behind_a_ray)
 {
     Ray r = Ray(Point(0, 0, 5), Vector(0, 0, 1));
     Sphere s = Sphere();
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 2);
     ASSERT_EQ(xs[0].t, -6.0);
@@ -89,7 +89,7 @@ TEST(SphereTest, Intersecting_a_scaled_sphere_with_a_ray)
 
     s.setTransform(scaling(2, 2, 2));
 
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 2);
     ASSERT_EQ(xs[0].t, 3.0);
@@ -103,7 +103,7 @@ TEST(SphereTest, Intersecting_a_translated_sphere_with_a_ray)
 
     s.setTransform(translation(5, 0, 0));
 
-    Intersect xs = s.intersect(r);
+    Intersect xs; s.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }

tests/triangle_test.cpp

@@ -44,7 +44,7 @@ TEST(TriangleTest, Intersecting_a_ray_parallel_to_the_triangle)
     Triangle t = Triangle(Point(0, 1, 0), Point(-1, 0, 0), Point(1, 0, 0));
     Ray r = Ray(Point(0, -1, -2), Vector(0, 1, 0));
 
-    Intersect xs = t.intersect(r);
+    Intersect xs; t.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -54,7 +54,7 @@ TEST(TriangleTest, A_ray_miss_the_p1_p3_edge)
     Triangle t = Triangle(Point(0, 1, 0), Point(-1, 0, 0), Point(1, 0, 0));
     Ray r = Ray(Point(1, 1, -2), Vector(0, 0, 1));
 
-    Intersect xs = t.intersect(r);
+    Intersect xs; t.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -64,7 +64,7 @@ TEST(TriangleTest, A_ray_miss_the_p1_p2_edge)
     Triangle t = Triangle(Point(0, 1, 0), Point(-1, 0, 0), Point(1, 0, 0));
     Ray r = Ray(Point(-1, 1, -2), Vector(0, 0, 1));
 
-    Intersect xs = t.intersect(r);
+    Intersect xs; t.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -74,7 +74,7 @@ TEST(TriangleTest, A_ray_miss_the_p2_p3_edge)
     Triangle t = Triangle(Point(0, 1, 0), Point(-1, 0, 0), Point(1, 0, 0));
     Ray r = Ray(Point(0, -1, -2), Vector(0, 0, 1));
 
-    Intersect xs = t.intersect(r);
+    Intersect xs; t.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 0);
 }
@@ -84,7 +84,7 @@ TEST(TriangleTest, A_ray_strikes_a_triangle)
     Triangle t = Triangle(Point(0, 1, 0), Point(-1, 0, 0), Point(1, 0, 0));
     Ray r = Ray(Point(0, .5, -2), Vector(0, 0, 1));
 
-    Intersect xs = t.intersect(r);
+    Intersect xs; t.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 1);
     EXPECT_EQ(xs[0].t, 2);

tests/world_test.cpp

@@ -54,7 +54,8 @@ TEST(WorldTest, Intersect_a_world_with_a_ray)
     World w = DefaultWorld();
     Ray r = Ray(Point(0, 0, -5), Vector(0, 0, 1));
 
-    Intersect xs = w.intersect(r);
+    Intersect xs;
+    w.intersect(r, xs);
 
     ASSERT_EQ(xs.count(), 4);
     ASSERT_EQ(xs[0].t, 4);