Implement background colors.

4 files changed, 28 insertions, 5 deletions

diff --git a/dimension/grammar.y b/dimension/grammar.y
index ddc7418..01e2c0f 100644
--- a/dimension/grammar.y
+++ b/dimension/grammar.y
@@ -270,7 +270,7 @@ yyerror(YYLTYPE *locp, dmnsn_array *astree, dmnsn_token_iterator *iterator,
 %token DMNSN_T_AUTOSTOP
 %token DMNSN_T_AVERAGE
 %token DMNSN_T_B_SPLINE
-%token DMNSN_T_BACKGROUND
+%token DMNSN_T_BACKGROUND               "background"
 %token DMNSN_T_BEZIER_SPLINE
 %token DMNSN_T_BICUBIC_PATCH
 %token DMNSN_T_BLACK_HOLE
@@ -703,6 +703,10 @@ yyerror(YYLTYPE *locp, dmnsn_array *astree, dmnsn_token_iterator *iterator,
 /* Transformations */
 %type <astnode> TRANSFORMATION
 
+/* Atmospheric effects */
+%type <astnode> ATMOSPHERIC_EFFECT
+%type <astnode> BACKGROUND
+
 /* Objects */
 %type <astnode> OBJECT
 %type <astnode> FINITE_SOLID_OBJECT
@@ -749,7 +753,8 @@ SCENE: /* empty */ { }
      }
 ;
 
-SCENE_ITEM: OBJECT
+SCENE_ITEM: ATMOSPHERIC_EFFECT
+          | OBJECT
 ;
 
 /* Transformations */
@@ -765,6 +770,16 @@ TRANSFORMATION: "rotate" VECTOR {
               }
 ;
 
+/* Atmospheric effects */
+
+ATMOSPHERIC_EFFECT: BACKGROUND
+;
+
+BACKGROUND: "background" "{" COLOR "}" {
+            $$ = dmnsn_new_astnode1(DMNSN_AST_BACKGROUND, @$, $3);
+          }
+;
+
 /* Objects */
 
 OBJECT: FINITE_SOLID_OBJECT
@@ -1466,6 +1481,8 @@ dmnsn_astnode_string(dmnsn_astnode_type astnode_type)
   dmnsn_astnode_map(DMNSN_AST_SCALE, "scale");
   dmnsn_astnode_map(DMNSN_AST_TRANSLATION, "translate");
 
+  dmnsn_astnode_map(DMNSN_AST_BACKGROUND, "background");
+
   dmnsn_astnode_map(DMNSN_AST_BOX, "box");
   dmnsn_astnode_map(DMNSN_AST_SPHERE, "sphere");
   dmnsn_astnode_map(DMNSN_AST_LIGHT_SOURCE, "light_source");
diff --git a/dimension/lexer.l b/dimension/lexer.l
index 58bdc0e..d91855d 100644
--- a/dimension/lexer.l
+++ b/dimension/lexer.l
@@ -150,6 +150,7 @@ unsigned long wchar;
 }
 
 (?# Keywords)
+"background"    PUSH_TOKEN(DMNSN_T_BACKGROUND);
 "box"           PUSH_TOKEN(DMNSN_T_BOX);
 "blue"          PUSH_TOKEN(DMNSN_T_BLUE);
 "camera"        PUSH_TOKEN(DMNSN_T_CAMERA);
diff --git a/dimension/parse.h b/dimension/parse.h
index 1bf4436..f0bc994 100644
--- a/dimension/parse.h
+++ b/dimension/parse.h
@@ -29,6 +29,8 @@ typedef enum {
   DMNSN_AST_SCALE,
   DMNSN_AST_TRANSLATION,
 
+  DMNSN_AST_BACKGROUND,
+
   DMNSN_AST_BOX,
   DMNSN_AST_LIGHT_SOURCE,
   DMNSN_AST_SPHERE,
diff --git a/dimension/realize.c b/dimension/realize.c
index ac0231b..8d811fc 100644
--- a/dimension/realize.c
+++ b/dimension/realize.c
@@ -356,9 +356,7 @@ dmnsn_realize(const dmnsn_array *astree)
   scene->default_texture->finish->ambient = 0.1;
 
   /* Background color */
-  dmnsn_sRGB background_sRGB = { .R = 0.0, .G = 0.0, .B = 0.1 };
-  scene->background = dmnsn_color_from_sRGB(background_sRGB);
-  scene->background.filter = 0.1;
+  scene->background = dmnsn_black;
 
   /* Allocate a canvas */
   scene->canvas = dmnsn_new_canvas(768, 480);
@@ -403,6 +401,11 @@ dmnsn_realize(const dmnsn_array *astree)
     dmnsn_light  *light;
     dmnsn_object *object;
     switch (astnode.type) {
+    case DMNSN_AST_BACKGROUND:
+      dmnsn_array_get(astnode.children, 0, &astnode);
+      scene->background = dmnsn_realize_color(astnode);
+      break;
+
     case DMNSN_AST_BOX:
       object = dmnsn_realize_box(astnode);
       dmnsn_array_push(scene->objects, &object);