CSGnode.java

package com.gwief.jTrace;

/*
    CSGnode.java by Damian Newport
    acts as a node in the CSGtree
    Implements behavior to trace the tree
*/

import java.util.ArrayList;

public class CSGnode {
    
    Transform3D transform;
    CSGnode nodea;
    CSGnode nodeb;
    int op;     // 0 = union, 1 = intersection, 2 = difference, 3 = subtraction
    
    public CSGnode(){
        // do nothing
    }
    
    public CSGnode(CSGnode x ,int operator ,CSGnode y) {
        nodea = x;
        op = operator;
        nodeb = y;
        transform = new Transform3D();
    }

    public void settransform(Transform3D a){transform = a; }
    public Transform3D gettransform(){return transform; }
    
    Intersection[] getBranch(Ray ray){
        Intersection[] setA = nodea.getBranch(ray);
        Intersection[] setB = nodeb.getBranch(ray);
        int length = setA.length + setB.length;
        ArrayList output = new ArrayList();
        int current = 0;
        Intersection[] sorted = new Intersection[0];

        if (length == 0){ return sorted; }
        
        switch(op){
            case 0 : // union
                if (setA.length == 0) {return setB; }
                if (setB.length == 0) {return setA; }
                sorted = Intersection.mergeIntersections(setA, setB);
                for(int i = 0; i < length; i++){
                    current = current + sorted[i].type;
                    if((current == 1) && (sorted[i].type > 0)){
                        output.add(sorted[i]);
                    }else if((current == 0) && (sorted[i].type < 0)){
                        output.add(sorted[i]);
                    }
                }
                break;
            case 1 : // intersection
                if (setA.length == 0) {return sorted; }
                if (setB.length == 0) {return sorted; }
                sorted = Intersection.mergeIntersections(setA, setB);
                for(int i = 0; i < length; i++){
                    current = current + sorted[i].type;
                    if((current == 2) && (sorted[i].type > 0)){
                        output.add(sorted[i]);
                    }else if((current == 1) && (sorted[i].type < 0)){
                        output.add(sorted[i]);
                    }
                }
                break;
            case 2 : // difference
                if (setA.length == 0) {return setB; }
                if (setB.length == 0) {return setA; }
                sorted = Intersection.mergeIntersections(setA, setB);
                for(int i = 0; i < length; i++){
                    current = current + sorted[i].type;
                    if((current == 1) && (sorted[i].type > 0)){
                        output.add(sorted[i]);
                    }else if((current == 2) && (sorted[i].type > 0)){
                        sorted[i].type = -1;
                        output.add(sorted[i]);
                    }else if((current == 1) && (sorted[i].type < 0)){
                        sorted[i].type = 1;
                        output.add(sorted[i]);
                    }else if((current == 0) && (sorted[i].type < 0)){
                        output.add(sorted[i]);
                    }
                }
                break;
            case 3 : // subtraction
                if (setA.length == 0) {return sorted; }
                if (setB.length == 0) {return setA; }
                int lengthB = setB.length;
                for(int j = 0; j < lengthB; j++){
                    setB[j].type = setB[j].type * -1;
                }
                sorted = Intersection.mergeIntersections(setA, setB);
                for(int i = 0; i < length; i++){
                    current = current + sorted[i].type;
                    if((current == 1) && (sorted[i].type > 0)){
                        output.add(sorted[i]);
                    }else if((current == 0) && (sorted[i].type < 0)){
                        output.add(sorted[i]);
                    }
                }
                break;
            default :
                System.out.println("Error! Unidentified operator in CSGnode : " + op);
                System.exit(1);
        }
        Intersection[] empty = new Intersection[output.size()];
        output.toArray(empty);
        return empty;
    }
    
    public void build(Transform3D ntrans){
        Transform3D ttrans = new Transform3D(ntrans);
        ttrans.multiply(transform);
        nodea.build(ttrans);
        nodeb.build(ttrans);
    }
}