added exposure equations to avoid saturation; default exposure 1.0; added "exposure" keyword to global scene options in parser

git-svn-id: svn://anubis/fart/trunk@250 7f9b0f55-74a9-4bce-be96-3c2cd072584d

main/Scene-load.cc

@@ -184,6 +184,12 @@ void Scene::processOptions(refptr<Node> node)
         {
             m_height = (*it)->getInteger();
         }
+        else if ( typeid(**it) == typeid(ExposureNode) )
+        {
+            m_exposure = (*it)->getNumber();
+            if (m_exposure < 0.0)
+                m_exposure = 0.0;
+        }
         else if ( typeid(**it) == typeid(MultisampleNode) )
         {
             m_multisample_level = (*it)->getInteger();

main/Scene.cc

@@ -1,6 +1,7 @@
 
-#include "Scene.h"
+#include <math.h>               /* exp(), pow() */
 #include <stdlib.h>
+
 #include <string>
 #include <vector>
 #include <utility>              /* pair */
@@ -8,7 +9,8 @@
 #include <algorithm>            /* sort() */
 #include <functional>           /* binary_function */
 #include <typeinfo>             /* typeid operator support */
-#include <math.h>
+
+#include "Scene.h"
 #include "BMP.h"
 #include "util/Color.h"
 #include "shapes/Shape.h"
@@ -23,8 +25,9 @@ Scene::Scene(const map<string, const char *> & options,
     m_height = 600;
     m_multisample_level = 1;
     m_vfov = 60.0;
-    m_ambient_light = Color(0.2, 0.2, 0.2);
+    m_ambient_light = Color(0.1, 0.1, 0.1);
     m_max_depth = 10;
+    m_exposure = 1.0f;
     m_transforms.push(Transform());
 
     load(filename);
@@ -86,13 +89,25 @@ void Scene::renderPixel(int x, int y, unsigned char * pixel)
         }
     }
 
+    /* apply exposure formula so we aren't saturated */
+    finalColor.r = 1.0f -
+        exp(-m_exposure * finalColor.r / m_multisample_level_squared);
+    finalColor.g = 1.0f -
+        exp(-m_exposure * finalColor.g / m_multisample_level_squared);
+    finalColor.b = 1.0f -
+        exp(-m_exposure * finalColor.b / m_multisample_level_squared);
+
+#if 0
+    /* gamma correct */
+    finalColor.r = pow(finalColor.r, 1 / 2.2);
+    finalColor.g = pow(finalColor.g, 1 / 2.2);
+    finalColor.b = pow(finalColor.b, 1 / 2.2);
+#endif
+
     /* take the average of all the samples as the final pixel value */
-    pixel[BMP_RED] = (unsigned char)
+    pixel[BMP_RED]   = (unsigned char) (0xFF * finalColor.r);
-        (0xFF * finalColor.r / m_multisample_level_squared);
+    pixel[BMP_GREEN] = (unsigned char) (0xFF * finalColor.g);
-    pixel[BMP_GREEN] = (unsigned char)
+    pixel[BMP_BLUE]  = (unsigned char) (0xFF * finalColor.b);
-        (0xFF * finalColor.g / m_multisample_level_squared);
-    pixel[BMP_BLUE] = (unsigned char)
-        (0xFF * finalColor.b / m_multisample_level_squared);
 }
 
 Color Scene::traceRay(const Ray & ray)
@@ -244,14 +259,6 @@ Color Scene::computePhong(const refptr<Material> material,
         }
     }
 
-    /* TODO: figure out better scaling */
-    if (result.r > 1.0)
-        result.r = 1.0;
-    if (result.g > 1.0)
-        result.g = 1.0;
-    if (result.b > 1.0)
-        result.b = 1.0;
-
     return result;
 }
 

main/Scene.h

@@ -77,6 +77,7 @@ class Scene
         double m_vfov;
         Color m_ambient_light;
         int m_max_depth;
+        double m_exposure;
 
         /* private data */
         std::vector< refptr<Shape> > m_shapes;

parser/nodes.h

@@ -96,6 +96,12 @@ class DiffuseNode : public VectorNode
         DiffuseNode(refptr<Vector> vector) : VectorNode(vector) {}
 };
 
+class ExposureNode : public NumberNode
+{
+    public:
+        ExposureNode(double d) : NumberNode(d) {}
+};
+
 class HeightNode : public IntegerNode
 {
     public:

parser/parser.lex

@@ -46,6 +46,7 @@ color               return COLOR;
 cyl                 return CYL;
 define              return DEFINE;
 diffuse             return DIFFUSE;
+exposure            return EXPOSURE;
 height              return HEIGHT;
 intersect           return INTERSECT;
 light               return LIGHT;

parser/parser.yy

@@ -65,6 +65,7 @@ static refptr<Node> parsed_scene_node;
 %token CYL;
 %token DEFINE;
 %token DIFFUSE;
+%token EXPOSURE;
 %token HEIGHT;
 %token INTERSECT;
 %token LIGHT;
@@ -295,6 +296,9 @@ options_item: WIDTH DEC_NUMBER {
             | MAXDEPTH DEC_NUMBER {
                     $$ = new MaxDepthNode($2->getInteger());
                 }
+            | EXPOSURE number {
+                    $$ = new ExposureNode($2->getNumber());
+                }
             ;
 
 plane: PLANE LCURLY plane_items RCURLY {