Overview

This example demonstrates how to optimize the layout of 2D patterns (drawings) on material sheets using the nesting tool (Nesting_Computer ). For this purpose, a console application is used, which defines nesting parameters, creates patterns, and executes the nesting process. The tool computes an optimal arrangement of parts to minimize material waste and maximize placement efficiency.

For more information about nesting, refer to the Nesting Process.

Implementation

The nesting process begins by creating an instance of the Nesting_Computer class, which serves as the primary tool for optimizing the arrangement of 2D patterns. This is followed by defining and configuring the nesting parameters using the Nesting_ComputerParameters class:

using namespace cadex;
 
Nesting_Computer aComputer;
 
// Configuring nesting parameters
Nesting_ComputerParameters aParams;
aParams.SetIterationCount (10);               // Number of iterations for optimization process
aParams.SetGenerationSize (10);               // Initial count of random layouts
aParams.SetMutationRate (0.5);                // Probability of random patterns rearrangement to escape local optima
aParams.SetPartToPartDistance (1.0);          // Minimum distance between patterns
aParams.SetPartToSheetBoundaryDistance (1.0); // Minimum distance between patterns and sheet edges
aParams.SetMirrorControl (false);             // Enables or disables the use of mirrored patterns
aParams.SetRotationCount (4);                 // Number of allowed rotation angles (e.g., 4 allows 0°, 90°, 180°, and 270°)
aParams.SetCurveTolerance (10);               // Side length of squares used for polygonal approximation of curves
 
aComputer.SetParameters (aParams);

The dimensions and number of sheets are defined using AddMaterial() method:

using namespace cadex;
 
// Define material size and number (e.g., 1 sheets of 100x100 mm)
aComputer.AddMaterial (100.0, 100.0, 1);

A Pattern is essentially a Drawing::View combined with metadata, such as the pattern name and number:

using namespace cadex;
 
class Pattern
{
public:
 
    Pattern (const Drawing::CurveSet theShape, const UTF16String theName, size_t theNumber) :
        myName (theName), 
        myNumber (theNumber)
    {
        myDrawingView.Add (theShape);
    }
 
    Drawing::View myDrawingView;
    UTF16String   myName;
    size_t        myNumber;
};

Rectangular patterns are created using the CreateRectangle function and added to a PatternVector:

using namespace cadex;
 
using PatternVector = vector<Pattern>;
 
Drawing::CurveSet CreateRectangle (double theWidth, double theHeight)
{
    Drawing::CurveSet aRectangle;
 
    Geom::Line2d aL1 (Geom::Point2d (0, 0), Geom::Direction2d (1, 0));
    aL1.SetTrim (0, theWidth);
 
    Geom::Line2d aL2 (Geom::Point2d (theWidth, 0), Geom::Direction2d (0, 1));
    aL2.SetTrim (0, theHeight);
 
    Geom::Line2d aL3 (Geom::Point2d (theWidth, theHeight), Geom::Direction2d (-1, 0));
    aL3.SetTrim (0, theWidth);
 
    Geom::Line2d aL4 (Geom::Point2d (0, theHeight), Geom::Direction2d (0, -1));
    aL4.SetTrim (0, theHeight);
 
    aRectangle.AddCurve (aL1);
    aRectangle.AddCurve (aL2);
    aRectangle.AddCurve (aL3);
    aRectangle.AddCurve (aL4);
 
    return aRectangle;
}
 
auto aPatterns = PatternVector{Pattern (CreateRectangle (50.0, 50.0), "Rectangle 50x50", 1),
                               Pattern (CreateRectangle (20.0, 10.0), "Rectangle 20x10", 10)};

The patterns are loaded into the Nesting_Computer , which performs the nesting process and generates a Nesting_Data object containing the results.

using namespace cadex;
 
// Loading part patterns (rectangles) into the computer
for (const auto& aPattern : aPatterns) {
    aComputer.AddPattern (aPattern.myDrawingView, aPattern.myNumber);
}
 
// Start the Nesting process
Nesting_Data aData = aComputer.Perform();

Example output

Below is the example output:

------- Patterns Info -------
Rectangle 50x50: 1
Rectangle 20x10: 10
 
------- Nesting Info -------
#0 Sheet
   Nested Parts: 11
   Scrap: 55%
   Placement Efficiency: 90.58%
 
Average Scrap: 55%
Average Placement Efficiency: 90.58%

Table of Contents

Overview

Implementation

Example output

Files