Lesson
Challenge
Standards

OpenSCAD

render()
Adding render() before a code block forces OpenSCAD to render and cache the mesh produced by that code, making each successive render much faster.

An Example
The following OpenSCAD program was a dissection of member Emmett Lalish's file Rhombic Dodecahedra Chain.
  1. Starting with the following shapes where L= the height of the module and in this case 40: 
        translate ([-60,0,0])rotate([0,0,45])cube(L*[1,1,2],center=true);
    translate ([0,0,0])rotate([0,45,0])cube(L*[1,2,1],center=true);
    translate ([70,0,0])rotate([45,0,0])cube(L*[2,1,1],center=true);


  2. Combine each shape by using intersection(). The shape created will be just where the three shapes intersect: 
    intersection(){
    rotate([0,0,45])cube(L*[1/s,1/s,2],center=true);
    rotate([0,45,0])cube(L*[s,2,s],center=true);
    rotate([45,0,0])cube(L*[2,s,s],center=true);
}


  3. Now you want to create another form using these shapes.
    Here L is still 40, and s=fraction of the face to hollow/2+0.5 
    translate([-70,0,0])rotate([0,0,45])cube(L*[1/s,1/s,2],center=true);
translate([20,0,0])rotate([0,45,0])cube(L*[s,2,s],center=true);
translate([100,0,0])rotate([45,0,0])cube(L*[2,s,s],center=true);


  4. Combine each shape again by using intersection(). The shape created will be just where the three shapes intersect: 
    intersection(){
    rotate([0,0,45])cube(L*[1/s,1/s,2],center=true);
    rotate([0,45,0])cube(L*[s,2,s],center=true);
    rotate([45,0,0])cube(L*[2,s,s],center=true);
}


  5. You should now have two shapes:

    The next thing to do is create a boolean difference of the second form from the first form:


  6. The next step is the continue differencing from the initial form. This time you will rotate the second form 90° on the X axis:


  7. The last step is to create another difference from the initial form. This time rotate the second form 90° on the Y axis:


  8. If you wanted to see how the form falls on the platform, you could add a cube: 
    %cube([220,140,1],center=true);


  9. Rotating the form by 45° on the X axis and 90° on the Z axis will straighten the form: 
    rotate([45,0,90])


  10. Now to raise the form to sit on the platform: 
    rotate([45,0,90])


  11. Surround the code with 
    render(){

}


  12. Then put it in a module: 
    module openRhom(){
   render(){
       translate([0,0,L/2])
       rotate([45,0,90])
       difference(){
          firstShape();
          secondShape();
          rotate([90,0,0])secondShape();
          rotate([0,90,0])secondShape();
       }
    }
}


  13. Now you can quickly preview chains. Here set a variable d to be the 16.5: 
    chain(20);
module chain(n){
    translate([-(n-1)*1*d+d,0,0])
    for(i=[1:n]){
	    translate([(i-1)*2*d,0,0])
	    openRhom();
    }    
}