mold.scad

// Copyright (c) 2019 William Barkoff, Caitlin Monsky, Matteo Bertoni
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software
// and associated documentation files (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all copies or substantial
// portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
// OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 

// Based on http://www.thingiverse.com/Ablapo/designs, which is
// licensed under CC BY 3.0 License (https://creativecommons.org/licenses/by/3.0/)

module paraboloid (y=10, f=5, rfa=0, fc=1, detail=44){
	// y = height of paraboloid
	// f = focus distance 
	// fc : 1 = center paraboloid in focus point(x=0, y=f); 0 = center paraboloid on top (x=0, y=0)
	// rfa = radius of the focus area : 0 = point focus
	// detail = $fn of cone

	hi = (y+2*f)/sqrt(2);								// height and radius of the cone -> alpha = 45° -> sin(45°)=1/sqrt(2)
	x =2*f*sqrt(y/f);									// x  = half size of parabola
	
   translate([0,0,-f*fc])								// center on focus 
	rotate_extrude(convexity = 10,$fn=detail )		// extrude paraboild
	translate([rfa,0,0])								// translate for fokus area	 
	difference(){
		union(){											// adding square for focal area
			projection(cut = true)																			// reduce from 3D cone to 2D parabola
				translate([0,0,f*2]) rotate([45,0,0])													// rotate cone 45° and translate for cutting
				translate([0,0,-hi/2])cylinder(h= hi, r1=hi, r2=0, center=true, $fn=detail);   	// center cone on tip
			translate([-(rfa+x ),0]) square ([rfa+x , y ]);											// focal area square
		}
		translate([-(2*rfa+x ), -1/2]) square ([rfa+x ,y +1] ); 					// cut of half at rotation center 
	}
}

difference(){
	paraboloid(y=50,f=10,rfa= 0,fc=1,detail=120);
	translate([0, 0, 5]) {
		scale([.95, .95, .95]) {
			paraboloid(y=50,f=10,rfa= 0,fc=1,detail=120);
		}
	}
}