Adds rich transparency for shaders and implements if for light calculations

light/pointlight.cpp

@@ -20,8 +20,10 @@ Light::Illumination PointLight::illuminate(Scene const &scene, Ray const &ray) c
   lightRay.length = distance - LGT_EPS;
 
   // If the target is not in shadow...
-  if (!scene.findOcclusion(lightRay))
+  if (!scene.findOcclusion(lightRay)) {
     // ... compute the attenuation and light color
-    illum.color = 1.0f / (distance * distance) * this->color * this->intensity;
+    Color rayTransparency = scene.getTransparency(lightRay, distance);
+    illum.color = 1.0f / (distance * distance) * this->color * this->intensity * rayTransparency;
+  }
   return illum;
 }

light/spotlight.cpp

@@ -28,7 +28,8 @@ Light::Illumination SpotLight::illuminate(Scene const &scene, Ray const &ray) co
     // ... and not in shadow ...
     if (!scene.findOcclusion(lightRay)) {
       // ... compute the attenuation and light color ...
-      illum.color = 1.0f / (distance * distance) * this->color * this->intensity;
+      Color rayTransparency = scene.getTransparency(lightRay, distance);
+      illum.color = 1.0f / (distance * distance) * this->color * this->intensity * rayTransparency;
       // ... then compute the falloff towards the edge of the cone
       if (this->alphaMin < alpha)
         illum.color *= 1.0f - (alpha - this->alphaMin) / (this->alphaMax - this->alphaMin);

light/sunlight.cpp

@@ -25,7 +25,9 @@ Light::Illumination SunLight::illuminate(Scene const &scene, Ray const &ray) con
         // Look at angleIntensity of light
         float angleIntensity = dotProduct(-ray.normal,
                                           this->direction);  // 0 if light is behind surface, 1 if light is in front of surface
-        illum.color = this->color * this->intensity * angleIntensity;
+
+        Color rayTransparency = scene.getTransparency(lightRay, INFINITY);
+        illum.color = this->color * this->intensity * angleIntensity * rayTransparency;
     }
     return illum;
 }

scene/fastscene.cpp

@@ -221,3 +221,27 @@ std::unique_ptr<Node> FastScene::build(Vector3d const &minimumBounds, Vector3d c
   node->child[1] = this->build(minimumSplit, maximumBounds, rightPrimitives, depth);
   return node;
 }
+
+Color FastScene::getTransparency(Ray &ray, float maxDistance) const
+{
+    // TODO: Not taking advantage of the tree structure!
+
+    ray.length = maxDistance;
+    ray.primitive = nullptr;
+
+    Color transparency(1, 1, 1);
+    for (auto i: this->primitives())
+    {
+        Ray r = ray;
+        if (i->intersect(r) && r.length < maxDistance && i->shader()->isTransparent())
+        {
+            r.length = maxDistance; // To allow transparency to be calculated partially for objects
+
+            Color t = i->shader()->transparency(*this, r);
+            transparency.r *= t.r;
+            transparency.g *= t.g;
+            transparency.b *= t.b;
+        }
+    }
+    return transparency;
+}

scene/fastscene.h

@@ -28,6 +28,7 @@ public:
   // Raytracing functions
   bool findIntersection(Ray &ray) const override;
   bool findOcclusion(Ray &ray) const override;
+  Color getTransparency(Ray &ray, float maxDistance) const override;
   int countNodeIntersections(const Ray &ray) const;
 
   // Setup functions

scene/scene.h

@@ -41,6 +41,7 @@ public:
   Color traceRay(Ray &ray) const;
   virtual bool findIntersection(Ray &ray) const = 0;
   virtual bool findOcclusion(Ray &ray) const = 0;
+  virtual Color getTransparency(Ray &ray, float maxDistance) const = 0;
 
 protected:
   Color backgroundColor;

scene/simplescene.cpp

@@ -2,16 +2,40 @@
 #include "primitive/primitive.h"
 #include "shader/shader.h"
 
-bool SimpleScene::findIntersection(Ray &ray) const {
-  bool hit = false;
-  for (auto i : this->primitives())
-    hit |= i->intersect(ray);
-  return hit;
+bool SimpleScene::findIntersection(Ray &ray) const
+{
+    bool hit = false;
+    for (auto i: this->primitives())
+        hit |= i->intersect(ray);
+    return hit;
 }
 
-bool SimpleScene::findOcclusion(Ray &ray) const {
-  for (auto i : this->primitives())
-    if (i->intersect(ray) && !i->shader()->isTransparent())
-      return true;
-  return false;
+bool SimpleScene::findOcclusion(Ray &ray) const
+{
+    for (auto i: this->primitives())
+        if (i->intersect(ray) && !i->shader()->isTransparent())
+            return true;
+    return false;
+}
+
+Color SimpleScene::getTransparency(Ray &ray, float maxDistance) const
+{
+    ray.length = maxDistance;
+    ray.primitive = nullptr;
+
+    Color transparency(1, 1, 1);
+    for (auto i: this->primitives())
+    {
+        Ray r = ray;
+        if (i->intersect(r) && r.length < maxDistance && i->shader()->isTransparent())
+        {
+            r.length = maxDistance; // To allow transparency to be calculated partially for objects
+
+            Color t = i->shader()->transparency(*this, r);
+            transparency.r *= t.r;
+            transparency.g *= t.g;
+            transparency.b *= t.b;
+        }
+    }
+    return transparency;
 }

scene/simplescene.h

@@ -9,6 +9,7 @@ public:
   // Raytracing functions
   bool findIntersection(Ray &ray) const override;
   bool findOcclusion(Ray &ray) const override;
+  Color getTransparency(Ray &ray, float maxDistance) const override;
 };
 
 #endif

shader/refractionshader.cpp

@@ -1,7 +1,8 @@
 #include "scene/scene.h"
 #include "shader/refractionshader.h"
 
-RefractionShader::RefractionShader(float indexInside, float indexOutside, Color const &objectColor, float lightLoss) : indexInside(
+RefractionShader::RefractionShader(float indexInside, float indexOutside, Color const &objectColor, float lightLoss)
+        : indexInside(
         indexInside), indexOutside(indexOutside), objectColor(objectColor), lightLoss(lightLoss)
 {}
 
@@ -52,14 +53,36 @@ Color RefractionShader::shade(Scene const &scene, Ray const &ray) const
 
         // Send out a new refracted ray into the scene
         Color hitColor = scene.traceRay(refractionRay);
-
-        // Calculate light lost
         float lightRemaining = 1;
-        if (refractionRay.primitive == ray.primitive) lightRemaining = 1 - lightLoss + exp(-refractionRay.length / 10) * lightLoss;
+        if (ray.primitive == refractionRay.primitive) lightRemaining = remainingLightIntensity(refractionRay.length);
+
         return hitColor * objectColor * lightRemaining;
     }
     return Color(0.0f, 0.0f, 0.0f);
 }
 
+float RefractionShader::remainingLightIntensity(float distanceThroughObject) const
+{
+    return 1 - lightLoss + exp(-distanceThroughObject / 10) * lightLoss;
+}
+
 bool RefractionShader::isTransparent() const
 { return true; }
+
+Color RefractionShader::transparency(const Scene &scene, const Ray &ray) const
+{
+    // Determine length through the object
+    Ray lengthRay = ray;
+    // Reset the ray
+    lengthRay.length = INFINITY;
+    lengthRay.primitive = nullptr;
+    lengthRay.origin = ray.origin + (ray.length + REFR_EPS) * ray.direction;
+
+    scene.traceRay(lengthRay);
+
+    float transparencyDistance = std::min(ray.length, lengthRay.length);
+    float lightRemaining = 1;
+    if (ray.primitive == lengthRay.primitive) lightRemaining = remainingLightIntensity(transparencyDistance);
+
+    return objectColor * lightRemaining;
+}

shader/refractionshader.h

@@ -14,12 +14,15 @@ public:
     Color shade(Scene const &scene, Ray const &ray) const override;
 
     bool isTransparent() const override;
+    Color transparency(Scene const &scene, Ray const &ray) const override;
 
 private:
     float indexInside;
     float indexOutside;
     float lightLoss;
     Color objectColor;
+
+    float remainingLightIntensity(float distanceThroughObject) const;
 };
 
 #endif

shader/shader.h

@@ -7,17 +7,29 @@
 // Forward declarations
 class Scene;
 
-class Shader {
+class Shader
+{
 public:
-  // Constructor / Desctructor
-  Shader() = default;
-  virtual ~Shader() = default;
+    // Constructor / Desctructor
+    Shader() = default;
 
-  // Get
-  virtual bool isTransparent() const { return false; }
+    virtual ~Shader() = default;
 
-  // Shader functions
-  virtual Color shade(Scene const &scene, Ray const &ray) const = 0;
+    // Get
+    virtual bool isTransparent() const
+    { return false; }
+
+    /**
+     * Especially used for lighting calculations.
+     * @brief Returns the light let through the shader in opposite direction of the given ray.
+     * @param ray Origin and direction of the desired path.
+     * @return 0 if the shader is opaque, 1 if the shader is transparent, for each color channel.
+     */
+    virtual Color transparency(Scene const &scene, Ray const &ray) const
+    { return isTransparent() ? Color(1, 1, 1) : Color(0, 0, 0); }
+
+    // Shader functions
+    virtual Color shade(Scene const &scene, Ray const &ray) const = 0;
 };
 
 #endif