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docs/lib2x-sweep.md

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+# sweep
+
+This module sweeps multiple cross-sections to create a 3D object. For example, imagine that you have the following cross-sections:
+
+![sweep](images/lib2x-sweep-1.JPG)
+
+This module sweeps them to create a 3D object:
+
+![sweep](images/lib2x-sweep-2.JPG)
+
+When using this module, you should use points to represent a cross section. The points must be count-clockwise indexes. For example:
+
+![sweep](images/lib2x-sweep-10.JPG)
+
+If your cross section is hollow, set the `triangles` parameter to `"HOLLOW"` and index the points as the following:
+
+![sweep](images/lib2x-sweep-5.JPG)
+
+You can cut triangles by yourself. For example, the above shape can be cut into triangles such as:
+
+![sweep](images/lib2x-sweep-6.JPG)
+
+The indexes of the above triangles is:
+
+    [
+		[0, 3, 1],
+		[1, 3, 4],
+		[1, 4, 2],
+		[2, 4, 5],
+		[2, 5, 0],
+		[0, 5, 3]
+	]
+
+## Parameters
+
+- `sections` : A list of cross-sections. Each cross-section is represented by points. See the example below.
+- `triangles` : `"SOLID"` (default), `"HOLLOW"`,  or user-defined indexes. See example below.
+
+## Examples
+
+	use <rotate_p.scad>;
+	use <sweep.scad>;
+
+	section1 = [
+		[20, 0, 0],
+		[18, 9, 0],
+		[15, 10, 0],
+		[10, 0, 0]
+	];
+
+	// spin section1
+	sections = [
+		for(i = [0:55]) 
+			[
+				for(p = section1)
+					let(pt = rotate_p(p, [90, 0, 10 * i]))
+					[pt[0], pt[1] , pt[2] + i]
+			]
+	];
+
+	sweep(sections);
+
+![sweep](images/lib2x-sweep-7.JPG)
+
+	use <rotate_p.scad>;
+	use <sweep.scad>;
+	
+	section1 = [
+	    // outer
+		[20, 0, 0],
+		[18, 9, 0],
+		[15, 10, 0],
+		[10, 0, 0],
+	    // inner
+        [18, 2, 0],
+        [17, 7, 0],
+        [15, 7, 0],
+	    [12, 2, 0]
+	];
+	
+	// spin section1
+	sections = [
+	    for(i = [0:55]) 
+	        [
+	            for(p = section1)
+	                let(pt = rotate_p(p, [90, 0, 10 * i]))
+	                [pt[0], pt[1] , pt[2] + i]
+	        ]
+	];
+	    
+	sweep(sections, "HOLLOW");
+
+![sweep](images/lib2x-sweep-8.JPG)
+
+	use <rotate_p.scad>;
+	use <sweep.scad>;
+	
+	section1 = [
+	    // outer
+        [30, 0, 0],
+	    [15, 10, 0],
+	    [10, 0, 0],
+	    // inner
+	    [26, 1, 0],
+	    [15, 8, 0],
+	    [12, 1, 0],        
+	];
+	
+	// spin section1
+	sections = [
+	    for(i = [0:55]) 
+	        [
+	            for(p = section1)
+	                let(pt = rotate_p(p, [90, 0, 10 * i]))
+	                [pt[0], pt[1] , pt[2] + i]
+	        ]
+	];
+	    
+	sweep(
+	   sections = sections, 
+	   triangles = [
+            [0, 3, 1],
+            [1, 3, 4],
+            [1, 4, 2],
+            [2, 4, 5],
+            [2, 5, 0],
+            [0, 5, 3]
+        ]
+	);
+
+![sweep](images/lib2x-sweep-9.JPG)
+
+
+
+