How To Make a Railing

Objects: cylinder, sphere.
Methods: #local, #declare, union, #macro, #while loops.

This example shows how to make a railing i.e. for bridges declared as a macro. The vertical supports are distributed in an equidistant way. It is possible to use variable sizes for the dimensions of the railing.

The Construction in details:
 
Step 1: First we declare a macro with the basic variables for the dimensions of the railing and its default texture (To change this texture, declare it before including the macro!).

#macro Railing_1( R_Len,// railing length in x R_H, // railing height in y R_D, // verticals ~distance R_R, // railing main radius VSD, // vertical subdivision )//----------------------------- // default texture ----------------------------- #ifndef( Railing_Texture_1 ) #declare Railing_Texture_1 = texture { pigment{ color rgb<1,1,1>*0.7} normal { bumps 0.25 scale 0.35} finish { phong 0.3 } } // end of texture #end // ---------------------------------------- // horizontal subdivision ---------------------- #local NumV = int ( R_Len / R_D); #local VerticalsDistance = R_Len / NumV; // equidistant! //---------------------------------------------- //---------------------------------------------- union{ // horizontals cylinder{ <0,0,0>,<R_Len,0,0>,R_R translate<0,R_H ,0>} sphere{<0,0,0>,R_R translate< 0,R_H,0>} sphere{<0,0,0>,R_R translate<R_Len,R_H,0>} // vertical subdivision #if (VSD > 0) #local Nr = 0; // start loop #while (Nr < VSD ) cylinder{ <0,0,0>,<R_Len,0,0>, R_R*1/2 translate<0,Nr*R_H/(VSD),0>} #local Nr = Nr + 1; #end // end of loop #end // verticals #local Nr = 0; #while (Nr <= NumV) cylinder{ <0,0,0>,<0,R_H,0>, R_R translate<Nr*VerticalsDistance,0,0>} #local Nr = Nr +1 ; #end // end of loop texture{ Railing_Texture_1 } } // end of union // --------------------------------------------- #end // ------------------------ // end of macro

Step 2: Now we move this railing definition in an include file, than we can use this macro from any scene file as a
new ready-made object.
This file should be saved either in the same directory like the POV-Ray scene file, in the POV-Ray include file directory or in any include file directory with is mentioned as a Library_Path in the povray.ini file like:
Library_Path="C:\Users\MyFiles\MyPovrayFiles\My_include_files"

// POV-Ray 3.7/3.6 include file "Railing_1.inc" // author: Friedrich A, Lohmueller, Jan-2011 // homepage: www.f-lohmueller.de/ //---------------------------------------------- #ifndef( Railing_1_Inc_Temp) #declare Railing_1_Inc_Temp = version; #version 3.7; // 3.6; //--------------------------/////////////////// // macro 'Railing_1' //ADD HERE THE MACRO FROM ABOVE ! // end of macro 'Railing_1' //--------------------------/////////////////// /* sample: //ADD HERE A SAMPLE LIKE THE ONE BELOW ! */ end sample //---------------------------------------------- #version Railing_1_Inc_Temp; #end //------------------------- end of include file