ofApp.cpp

#include "ofApp.h"
#define EPS 1.0E-10

//--------------------------------------------------------------
void ofApp::setup(){

}

//--------------------------------------------------------------
void ofApp::update(){

}

//--------------------------------------------------------------
void ofApp::draw(){
    ofPushMatrix();
    ofTranslate(mouseX,mouseY);
    ofPoint lineStart(0,500,-150);
     ofPoint lineEnd(-900,500,-850);
    
    ofSetColor(255, 0, 0);
    ofDrawLine(lineStart,lineEnd);

    ofPoint lineStart2(-1000,500, -750);
    ofPoint lineEnd2(1000,500, -750);
    
    ofSetColor(0, 0, 255);
    ofDrawLine(lineStart2,lineEnd2);

    ofPoint intersectPoint;
    bool bIntersect = ofLineSegmentIntersection(lineStart,lineEnd,lineStart2,lineEnd2,intersectPoint);
    
    ofPoint pa,pb;
    bool bIntersect2 = LineLineIntersect(lineStart,lineEnd, lineStart2,lineEnd2,pa,pb); //,mua,mub);

    ofLog()<<"bIntersect "<<bIntersect<<" intersectPoint "<<intersectPoint;
    ofLog()<<"bIntersect2 "<<bIntersect2<<" pa "<<pa<<" pb "<<pb;
    
    ofPopMatrix();
}

bool ofApp::LineLineIntersect(ofVec3f p1,ofVec3f p2,ofVec3f p3,ofVec3f p4, ofVec3f &pa,ofPoint &pb){ //},double *mua, double *mub){
    //http://paulbourke.net/geometry/pointlineplane/
    //http://paulbourke.net/geometry/pointlineplane/lineline.c
    //    ofVec3f pa;
    //    ofVec3f pb;
    double mua;
    double mub;
    
    ofPoint p13,p43,p21;
    double d1343,d4321,d1321,d4343,d2121;
    double numer,denom;
    
    p13.x = p1.x - p3.x;
    p13.y = p1.y - p3.y;
    p13.z = p1.z - p3.z;
    p43.x = p4.x - p3.x;
    p43.y = p4.y - p3.y;
    p43.z = p4.z - p3.z;
    if (ABS(p43.x) < EPS && ABS(p43.y) < EPS && ABS(p43.z) < EPS)
        return false;
    
    p21.x = p2.x - p1.x;
    p21.y = p2.y - p1.y;
    p21.z = p2.z - p1.z;
    if (ABS(p21.x) < EPS && ABS(p21.y) < EPS && ABS(p21.z) < EPS)
        return false;
    
    d1343 = p13.x * p43.x + p13.y * p43.y + p13.z * p43.z;
    d4321 = p43.x * p21.x + p43.y * p21.y + p43.z * p21.z;
    d1321 = p13.x * p21.x + p13.y * p21.y + p13.z * p21.z;
    d4343 = p43.x * p43.x + p43.y * p43.y + p43.z * p43.z;
    d2121 = p21.x * p21.x + p21.y * p21.y + p21.z * p21.z;
    
    denom = d2121 * d4343 - d4321 * d4321;
    if (ABS(denom) < EPS)
        return false;
    numer = d1343 * d4321 - d1321 * d4343;
    
    mua = numer / denom;
    mub = (d1343 + d4321 * (mua)) / d4343;
    
    pa.x = p1.x + mua * p21.x;
    pa.y = p1.y + mua * p21.y;
    pa.z = p1.z + mua * p21.z;
    pb.x = p3.x + mub * p43.x;
    pb.y = p3.y + mub * p43.y;
    pb.z = p3.z + mub * p43.z;
    
    //    ofLog()<<"mua "<<mua;
    //     ofLog()<<"mub "<<mub;
    //    ofLog()<<" pa pb dist "<<pa.distance(pb);
    return true;
}

//--------------------------------------------------------------
void ofApp::keyPressed(int key){

}

//--------------------------------------------------------------
void ofApp::keyReleased(int key){

}

//--------------------------------------------------------------
void ofApp::mouseMoved(int x, int y){

}

//--------------------------------------------------------------
void ofApp::mouseDragged(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mousePressed(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mouseReleased(int x, int y, int button){

}

//--------------------------------------------------------------
void ofApp::mouseEntered(int x, int y){

}

//--------------------------------------------------------------
void ofApp::mouseExited(int x, int y){

}

//--------------------------------------------------------------
void ofApp::windowResized(int w, int h){

}

//--------------------------------------------------------------
void ofApp::gotMessage(ofMessage msg){

}

//--------------------------------------------------------------
void ofApp::dragEvent(ofDragInfo dragInfo){ 

}

ofApp.h

#pragma once

#include "ofMain.h"


class ofApp : public ofBaseApp{
	public:
		void setup();
		void update();
		void draw();
		
		void keyPressed(int key);
		void keyReleased(int key);
		void mouseMoved(int x, int y);
		void mouseDragged(int x, int y, int button);
		void mousePressed(int x, int y, int button);
		void mouseReleased(int x, int y, int button);
		void mouseEntered(int x, int y);
		void mouseExited(int x, int y);
		void windowResized(int w, int h);
		void dragEvent(ofDragInfo dragInfo);
		void gotMessage(ofMessage msg);
    
        bool LineLineIntersect(ofVec3f p1,ofVec3f p2,ofVec3f p3,ofVec3f p4, ofVec3f &pa,ofPoint &pb);
};