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

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 {