Add line shadow shader

shader/wall/blank.geom

@@ -20,12 +20,9 @@ void main()
 
   vec4 a1 = theMat * p1;
   vec4 a2 = theMat * p2;
-
 //  if (0 > isLHS (a1.xy - a2.xy, a1.xy - "viewFromPoint")) {
-
-    vec4 p3 = vec4 (p1.xy,-0.5,1);
-    vec4 p4 = vec4 (p2.xy,-0.5,1);
-    
+    vec4 p3 = vec4 (p1.xy,150,1);
+    vec4 p4 = vec4 (p2.xy,150,1);
     vec4 a3 = theMat * p3;
     vec4 a4 = theMat * p4;