Finally! We have reflections!

source/include/intersection.h

@@ -16,8 +16,10 @@ class Shape;
 
 struct Computation
 {
-    Computation(Shape *object, double t, Tuple point, Tuple eyev, Tuple normalv, Tuple overHitP, bool inside) :
-          object(object), t(t), hitPoint(point), eyeVector(eyev), normalVector(normalv), inside(inside), overHitPoint(overHitP) { };
+    Computation(Shape *object, double t, Tuple point, Tuple eyev, Tuple normalv, Tuple overHitP,
+                bool inside, Tuple reflectV = Vector(0, 0, 0)) :
+          object(object), t(t), hitPoint(point), eyeVector(eyev), normalVector(normalv), inside(inside),
+          overHitPoint(overHitP),  reflectVector(reflectV) { };
 
     Shape *object;
     double t;
@@ -25,6 +27,7 @@ struct Computation
     Tuple overHitPoint;
     Tuple eyeVector;
     Tuple normalVector;
+    Tuple reflectVector;
 
     bool inside;
 };

source/include/material.h

@@ -24,11 +24,12 @@ public:
     double diffuse;
     double specular;
     double shininess;
+    double reflective;
 
     Pattern *pattern;
 
 public:
-    Material() : colour(Colour(1, 1, 1)), ambient(0.1), diffuse(0.9), specular(0.9), shininess(200), pattern(nullptr) {};
+    Material() : colour(Colour(1, 1, 1)), ambient(0.1), diffuse(0.9), specular(0.9), shininess(200), reflective(0.0), pattern(nullptr) {};
 
     Colour lighting(Light light, Tuple point, Tuple eyeVector, Tuple normalVector, Shape *hitObject, bool inShadow = false);
 

source/include/world.h

@@ -40,11 +40,14 @@ public:
     bool objectIsIn(Shape &s);
 
     Shape *getObject(int i) { return this->objectList[i]; };
+    Light *getLight(int i) { return this->lightList[i]; };
 
-    Tuple shadeHit(Computation comps);;
-    Tuple colourAt(Ray r);
+    Tuple shadeHit(Computation comps, uint32_t depthCount = 4);
+    Tuple colourAt(Ray r, uint32_t depthCount = 4);
     bool isShadowed(Tuple point);
 
+    Colour reflectColour(Computation comps, uint32_t depthCount = 4);
+
     Intersect intersect(Ray r);
 
 };

source/intersection.cpp

@@ -23,6 +23,7 @@ Computation Intersection::prepareComputation(Ray r)
     }
 
     Tuple overHitP = hitP + normalV * getEpsilon();
+    Tuple reflectV = r.direction.reflect(normalV);
 
     return Computation(this->object,
                        this->t,
@@ -30,5 +31,6 @@ Computation Intersection::prepareComputation(Ray r)
                        eyeV,
                        normalV,
                        overHitP,
-                       inside);
+                       inside,
+                       reflectV);
 }

source/world.cpp

@@ -92,17 +92,21 @@ Intersect World::intersect(Ray r)
     return ret;
 }
 
-Tuple World::shadeHit(Computation comps)
+Tuple World::shadeHit(Computation comps, uint32_t depthCount)
 {
     /* TODO: Add support for more than one light */
 
     bool isThereAnObstacle = this->isShadowed(comps.overHitPoint);
 
-    return comps.object->material.lighting(*this->lightList[0], comps.overHitPoint, comps.eyeVector,
+    Tuple surface = comps.object->material.lighting(*this->lightList[0], comps.overHitPoint, comps.eyeVector,
             comps.normalVector, comps.object, isThereAnObstacle);
+
+    Tuple reflected = this->reflectColour(comps, depthCount);
+
+    return surface + reflected;
 }
 
-Tuple World::colourAt(Ray r)
+Tuple World::colourAt(Ray r, uint32_t depthCount)
 {
     Intersection hit = this->intersect(r).hit();
 
@@ -112,7 +116,7 @@ Tuple World::colourAt(Ray r)
     }
     else
     {
-        return this->shadeHit(hit.prepareComputation(r));
+        return this->shadeHit(hit.prepareComputation(r), depthCount);
     }
 }
 
@@ -134,3 +138,21 @@ bool World::isShadowed(Tuple point)
 
     return false;
 }
+
+Colour World::reflectColour(Computation comps, uint32_t depthCount)
+{
+    if ((depthCount == 0) || (comps.object->material.reflective == 0))
+    {
+        return Colour(0, 0, 0);
+    }
+
+    /* So it is reflective, even just a bit. Let'sr reflect the ray! */
+    Ray reflectedRay = Ray(comps.overHitPoint, comps.reflectVector);
+
+    Tuple hitColour = this->colourAt(reflectedRay, depthCount - 1);
+    hitColour = hitColour * comps.object->material.reflective;
+
+    return Colour(hitColour.x, hitColour.y, hitColour.z);
+}
+
+

tests/CMakeLists.txt

@@ -44,8 +44,14 @@ target_include_directories(ch10_test PUBLIC ../source/include)
 target_sources(ch10_test PRIVATE ch10_test.cpp)
 target_link_libraries(ch10_test rayonnement)
 
+add_executable(ch11_reflection)
+target_include_directories(ch11_reflection PUBLIC ../source/include)
+target_sources(ch11_reflection PRIVATE ch11_reflection.cpp)
+target_link_libraries(ch11_reflection rayonnement)
+
 add_test(NAME Chapter05_Test COMMAND $<TARGET_FILE:ch5_test>)
 add_test(NAME Chapter06_Test COMMAND $<TARGET_FILE:ch6_test>)
 add_test(NAME Chapter07_Test COMMAND $<TARGET_FILE:ch7_test>)
 add_test(NAME Chapter09_Test COMMAND $<TARGET_FILE:ch9_test>)
 add_test(NAME Chapter10_Test COMMAND $<TARGET_FILE:ch10_test>)
+add_test(NAME Chapter11_Reflection COMMAND $<TARGET_FILE:ch11_reflection>)

tests/intersect_test.cpp

@@ -9,6 +9,7 @@
 #include <intersect.h>
 #include <intersection.h>
 #include <sphere.h>
+#include <plane.h>
 #include <transformation.h>
 #include <gtest/gtest.h>
 
@@ -190,3 +191,14 @@ TEST(IntersectTest, The_hit_should_offset_the_point)
     ASSERT_LT(comps.overHitPoint.z, -getEpsilon() / 2);
     ASSERT_GT(comps.hitPoint.z, comps.overHitPoint.z);
 }
+
+TEST(IntersectTest, Precomputing_the_reflection_vector)
+{
+    Plane s = Plane();
+    Ray r = Ray(Point(0, 1, -1), Vector(0, -sqrt(2) / 2, sqrt(2) / 2));
+    Intersection i = Intersection(sqrt(2), &s);
+
+    Computation comps = i.prepareComputation(r);
+
+    ASSERT_EQ(comps.reflectVector, Vector(0, sqrt(2) / 2, sqrt(2) / 2));
+}

tests/material_test.cpp

@@ -107,3 +107,10 @@ TEST(MaterialTest, Lighting_with_the_surface_in_shadow)
 
     ASSERT_EQ(result, Colour(0.1, 0.1, 0.1));
 }
+
+TEST(MaterialTest, Reflectivity_for_the_default_material)
+{
+    Material m = Material();
+
+    ASSERT_EQ(m.reflective, 0);
+}

tests/world_test.cpp

@@ -14,6 +14,7 @@
 #include <worldbuilder.h>
 #include <math.h>
 #include <gtest/gtest.h>
+#include <plane.h>
 
 
 TEST(WorldTest, Creating_a_world)
@@ -168,3 +169,108 @@ TEST(WorldTest, Shade_hit_is_given_an_intersection_in_shadow)
 
     ASSERT_EQ(c, Colour(0.1, 0.1, 0.1));
 };
+
+TEST(WorldTest, The_reflected_colour_for_a_non_reflective_material)
+{
+    World w = DefaultWorld();
+    Ray r = Ray(Point(0, 0, 0), Vector(0, 0, 1));
+
+    Shape *shape = w.getObject(1); /* The second object */
+    shape->material.ambient = 1; /* We use this to get a predictable colour */
+
+    Intersection i = Intersection(1, shape);
+
+    Computation comps = i.prepareComputation(r);
+    Colour colour = w.reflectColour(comps);
+
+    ASSERT_EQ(colour, Colour(0, 0, 0));
+}
+
+TEST(WorldTest, The_reflected_colour_for_a_reflective_material)
+{
+    World w = DefaultWorld();
+    Plane shape = Plane();
+    shape.material.reflective = 0.5;
+    shape.setTransform(translation(0, -1, 0));
+    w.addObject(&shape);
+
+    Ray r = Ray(Point(0, 0, -3), Vector(0, -sqrt(2)/2, sqrt(2)/2));
+
+    Intersection i = Intersection(sqrt(2), &shape);
+
+    Computation comps = i.prepareComputation(r);
+    Colour colour = w.reflectColour(comps);
+
+    /* Temporary lower the precision */
+    set_equal_precision(0.00002);
+
+    ASSERT_EQ(colour, Colour(0.19032, 0.2379, 0.14274));
+
+    set_equal_precision(FLT_EPSILON);
+}
+
+TEST(WorldTest, Shade_hit_with_a_reflective_material)
+{
+    World w = DefaultWorld();
+    Plane shape = Plane();
+    shape.material.reflective = 0.5;
+    shape.setTransform(translation(0, -1, 0));
+    w.addObject(&shape);
+
+    Ray r = Ray(Point(0, 0, -3), Vector(0, -sqrt(2)/2, sqrt(2)/2));
+
+    Intersection i = Intersection(sqrt(2), &shape);
+
+    Computation comps = i.prepareComputation(r);
+    Tuple colour = w.shadeHit(comps);
+
+    /* Temporary lower the precision */
+    set_equal_precision(0.00005);
+
+    ASSERT_EQ(colour, Colour(0.87677, 0.92436, 0.82918));
+
+    set_equal_precision(FLT_EPSILON);
+}
+
+TEST(WorldTest, Colour_at_with_mutually_reflective_surfaces)
+{
+    World w = World();
+
+    Light l = Light(POINT_LIGHT, Point(0, 0, 0), Colour(1, 1, 1));
+
+    w.addLight(&l);
+
+    Plane lower = Plane();
+    lower.material.reflective = 1;
+    lower.setTransform(translation(0, -1, 0));
+
+    Plane higher = Plane();
+    higher.material.reflective = 1;
+    higher.setTransform(translation(0, 1, 0));
+
+    w.addObject(&lower);
+    w.addObject(&higher);
+
+    Ray r = Ray(Point(0, 0, 0), Vector(0, 1, 0));
+
+    /* It should just exit, we don't care about the actual colour */
+    w.colourAt(r);
+}
+
+TEST(WorldTest, The_reflected_colour_at_the_maximum_recursion_depth)
+{
+    World w = DefaultWorld();
+    Plane shape = Plane();
+    shape.material.reflective = 0.5;
+    shape.setTransform(translation(0, -1, 0));
+    w.addObject(&shape);
+
+    Ray r = Ray(Point(0, 0, -3), Vector(0, -sqrt(2)/2, sqrt(2)/2));
+    Intersection i = Intersection(sqrt(2), &shape);
+
+    Computation comps = i.prepareComputation(r);
+    Tuple colour = w.reflectColour(comps, 0);
+
+    /* Temporary lower the precision */
+    ASSERT_EQ(colour, Colour(0, 0, 0));
+}