From f9cf1381a6402e429ea70e0320b3c86daa55e1d4 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Wed, 4 Mar 2009 02:03:21 +0000
Subject: [PATCH] working on shadows but they are appearing in weird places...

git-svn-id: svn://anubis/fart/trunk@185 7f9b0f55-74a9-4bce-be96-3c2cd072584d
---
 main/Scene.cc | 68 ++++++++++++++++++++++++++++++++++++++++-----------
 main/Scene.h  |  2 ++
 util/Ray.cc   |  5 ++++
 util/Ray.h    |  1 +
 4 files changed, 62 insertions(+), 14 deletions(-)

diff --git a/main/Scene.cc b/main/Scene.cc
index 37cffb5..4aa3a26 100644
--- a/main/Scene.cc
+++ b/main/Scene.cc
@@ -250,22 +250,31 @@ Color Scene::computePhong(const refptr<Material> material,
         Vector reflectedLightDirection =
             directionToLight.reflect(surfaceNormal);
 
-        /* calculate the diffuse term */
-        double diffuse_coef = directionToLight % surfaceNormal;
-        if (diffuse_coef > 0.0)
-        {
-            result += diffuseColor
-                    * (*it)->getDiffuseColor()
-                    * diffuse_coef;
-        }
+        Ray surfaceToLight(surfacePoint, directionToLight);
+        double light_contribution =
+            calculateLightContribution(surfaceToLight.shift(0.0001), *it);
 
-        /* calculate the specular term */
-        double specular_coef = reflectedLightDirection % viewDirection;
-        if (specular_coef > 0.0)
+        if (light_contribution > 0.0)
         {
-            result += specularColor
-                    * (*it)->getSpecularColor()
-                    * pow(specular_coef, shininess);
+            /* calculate the diffuse term */
+            double diffuse_coef = directionToLight % surfaceNormal;
+            if (diffuse_coef > 0.0)
+            {
+                result += diffuseColor
+                        * (*it)->getDiffuseColor()
+                        * diffuse_coef
+                        * light_contribution;
+            }
+
+            /* calculate the specular term */
+            double specular_coef = reflectedLightDirection % viewDirection;
+            if (specular_coef > 0.0)
+            {
+                result += specularColor
+                        * (*it)->getSpecularColor()
+                        * pow(specular_coef, shininess)
+                        * light_contribution;
+            }
         }
     }
 
@@ -279,6 +288,37 @@ Color Scene::computePhong(const refptr<Material> material,
 
     return result;
 }
+
+double Scene::calculateLightContribution(const Ray & toLight,
+                                         refptr<Light> light)
+{
+    double contrib = 1.0;
+    double dist_to_light = toLight.getOrigin().dist_to(light->getPosition());
+    double dist_so_far = 0.0;
+
+    Ray currentRay = toLight;
+
+    for (;;)
+    {
+        ShapeDistance hit = getRayClosestHit(currentRay);
+
+        if ( hit.shape.isNull() )
+            break;
+
+        if ( dist_so_far + hit.dist > dist_to_light )
+            break;
+
+        contrib *= hit.shape->getMaterial()->getTransparency();
+
+        if ( contrib < SCENE_FACTOR_THRESHOLD )
+            break;
+
+        dist_so_far += hit.dist + 0.0001;
+    }
+
+    return contrib;
+}
+
 bool operator<(const Scene::ShapeDistance & sd1,
                const Scene::ShapeDistance & sd2)
 {
diff --git a/main/Scene.h b/main/Scene.h
index efcd514..62b927e 100644
--- a/main/Scene.h
+++ b/main/Scene.h
@@ -56,6 +56,8 @@ class Scene
                            const Ray & viewRay,
                            const Vector & surfacePoint,
                            const Vector & surfaceNormal);
+        double calculateLightContribution(const Ray & toLight,
+                                          refptr<Light> light);
 
         /* In Scene-load.cc */
         void load(const char * filename);
diff --git a/util/Ray.cc b/util/Ray.cc
index 88baf51..ebf592c 100644
--- a/util/Ray.cc
+++ b/util/Ray.cc
@@ -31,3 +31,8 @@ std::ostream & operator<<(std::ostream & out, const Ray & r)
     out << "(" << r.getOrigin() << " -> " << r.getDirection() << ")";
     return out;
 }
+
+Ray Ray::shift(double amt)
+{
+    return Ray(getPositionAt(amt), m_direction);
+}
diff --git a/util/Ray.h b/util/Ray.h
index d251bfe..806a359 100644
--- a/util/Ray.h
+++ b/util/Ray.h
@@ -14,6 +14,7 @@ class Ray
         const Vector & getDirection() const { return m_direction; }
         Vector getPositionAt(double dist) const;
         Vector operator[](double dist) const { return getPositionAt(dist); }
+        Ray shift(double amt);
 
     protected:
         Vector  m_origin;