rt300@0: /*
rt300@0:  *  spring.cpp
rt300@0:  *  simplespring
rt300@0:  *
rt300@0:  *  Created by Robert Tubb on 02/06/2011.
rt300@0:  *  Copyright 2011 __MyCompanyName__. All rights reserved.
rt300@0:  *
rt300@0:  */
rt300@0: 
rt300@0: #include "spring.h"
rt300@0: #include "lump.h"
rt300@0: #include "globalForces.h"
rt300@0: 
rt300@0: #include <iostream>
rt300@0: #include "globalUI.h"
rt300@0: extern GlobalForces globalForces;
rt300@0: extern GlobalUI globalUI;
rt300@0: // statics
rt300@0: int Spring::numSprings = 0;
rt300@0: double Spring::maxForce = 0.0;
rt300@0: double Spring::minForce = 0.0;
rt300@0: bool Spring::forcesOn = true;
rt300@0: 
rt300@0: //---------------------------------------------------------------
rt300@0: Spring::Spring(){
rt300@0: 	//cout << "constructing a default spring" << endl;
rt300@3: 
rt300@3:     isInScanPath = false;
rt300@0: 	
rt300@3: 	springConst = 0.3; 
rt300@3: 
rt300@0: 	
rt300@0: 	startLumpPtr = 0;
rt300@0: 	endLumpPtr = 0;
rt300@0: 	restLength = 0.0;
rt300@0: 	myIndex = Spring::numSprings++;
rt300@0: 	maxForce = 0.005;
rt300@0: 	minForce = -0.005;
rt300@0: 	
rt300@0: 	force.x = 0.0;
rt300@0: 	force.y = 0.0;
rt300@0: 	
rt300@0: 	// width of a spring is proportional to how beefy it is
rt300@0: 	//ofSetLineWidth(springConst*2);
rt300@0: 	
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: Spring::Spring(double aStartx, double aStarty, double aEndx, double aEndy, double aK){
rt300@0: 	// hfsjsfhfshsgr
rt300@0: 
rt300@0: 
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: void Spring::attachLump(Lump * aLump){
rt300@0: 	// set position of spring start to mass position
rt300@0: 	if(startLumpPtr == 0){
rt300@0: 		startLumpPtr = aLump;
rt300@0: 		
rt300@0: 	}else if(endLumpPtr == 0){
rt300@0: 		endLumpPtr = aLump;
rt300@0: 		//cout << "----------------------------------------end point attached to " << endLumpPtr << endl;
rt300@0: 		updateEndPoints(); // now both ends attached - set the spring start and end points to the relevant lumps
rt300@0:         setRestLength(); // the default length for the spring can be set
rt300@0: 	}else{
rt300@0: 		cerr << "PERROR can't attach lump to this spring cos it's already attached both ends" << endl;
rt300@0: 	}
rt300@0: }
rt300@0: Lump * Spring::getLumpOnOtherEnd(Lump * alump){
rt300@0:     if (startLumpPtr == alump){
rt300@0:         return endLumpPtr;
rt300@0:         
rt300@0:     }else if (endLumpPtr == alump){
rt300@0:         return startLumpPtr;
rt300@0:     }
rt300@0:     cout << "getLumpOnOtherEnd: this should never happen" << endl;
rt300@0: 
rt300@0:     return NULL;
rt300@0: }
rt300@9: 
rt300@9: Lump * Spring::getStartLump(){
rt300@9:     return startLumpPtr;
rt300@9: }
rt300@9: Lump * Spring::getEndLump(){
rt300@9:     return endLumpPtr;
rt300@9: }
rt300@9: int Spring::getStartLumpIndex(){
rt300@9:     return startLumpPtr->myIndexInMesh;
rt300@9: }
rt300@9: int Spring::getEndLumpIndex(){
rt300@9:     return endLumpPtr->myIndexInMesh;
rt300@9: }
rt300@0: //---------------------------------------------------------------
rt300@0: void Spring::setRestLength(){
rt300@0: 
rt300@0: 	//set rest length according to what the length is now
rt300@0: 		TwoVector diff(startPoint.x - endPoint.x, startPoint.y - endPoint.y);
rt300@0: 	
rt300@0: 		restLength = diff.norm();	
rt300@0: 
rt300@0: 		//restLength = 0.0;
rt300@0: 
rt300@0: }
rt300@0: 	
rt300@0: void Spring::setRestLength(double aLength){
rt300@0: 	restLength = aLength;
rt300@0: 	
rt300@0: }
rt300@0: void Spring::setSpringConstant(double aK){
rt300@0:     springConst = aK;
rt300@0: }
rt300@0: double Spring::getLength(){
rt300@0:     return startPoint.distanceTo(endPoint);
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: void Spring::updateEndPoints(){
rt300@0: 	// tweak the end points eg: from mass move
rt300@0: 	if (startLumpPtr ==0 || endLumpPtr == 0){
rt300@0: 		cerr << "PERROR spring masses not attached!" << endl; 
rt300@0: 	}else{
rt300@0: 		startPoint = startLumpPtr->position;
rt300@0: 		//cout << "start pt x = " << startPoint.x << ", y = " << startPoint.y << endl;
rt300@0: 		endPoint = endLumpPtr->position;
rt300@0: 	}
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: void Spring::calculateForce(){
rt300@0: 
rt300@0: 	if(!Spring::forcesOn){
rt300@0: 		force.x = 0.0;
rt300@0: 		force.y = 0.0;
rt300@0:         return;
rt300@0: 	}
rt300@0: 	// get force from the extension
rt300@0: 	double xe = endPoint.x - startPoint.x;
rt300@0:     double ye = endPoint.y - startPoint.y;
rt300@0: 	double extendedLength = sqrt(xe*xe + ye*ye);
rt300@0: 	
rt300@0:     // doing this enables us to get away with only one division etc
rt300@0:     double FF = springConst*(restLength/extendedLength - 1.0);
rt300@0: 
rt300@0:     force.x = FF*xe;
rt300@0:     force.y = FF*ye;
rt300@0:   
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: TwoVector Spring::getForce(Lump * aLump){ // pass in the lump that we want the force for
rt300@0:     
rt300@0: 	// above force refers to force at END force at START negative of this...
rt300@0: 	if(aLump ==  startLumpPtr){
rt300@0:         TwoVector rForce;
rt300@0:         rForce.setCoord(-force.x, -force.y);
rt300@0:         return rForce;
rt300@0: 	}else if(aLump == endLumpPtr ){
rt300@0:         return force;
rt300@0:     }
rt300@0:     cout << "PERROR this lump is not attached to this spring\n";
rt300@0: 
rt300@0: 	return force;
rt300@0: 	
rt300@0: }
rt300@0: 
rt300@0: 
rt300@0: //---------------------------------------------------------------
rt300@0: void Spring::draw(){
rt300@0: 
rt300@0: 	int sxpos = startPoint.x * ofGetHeight() + globalUI.borderSize; // TODO make this nicer
rt300@0: 	int sypos = startPoint.y * ofGetHeight();
rt300@0: 	//cout << "start position = " << sxpos << "," << sypos << endl;
rt300@0: 	int expos = endPoint.x * ofGetHeight() + globalUI.borderSize;
rt300@0: 	int eypos = endPoint.y*ofGetHeight();
rt300@0: 	//cout << "end position = " << expos << "," << eypos << endl;
rt300@0: 
rt300@0: 	if(isInScanPath){
rt300@0:         ofSetLineWidth(4);
rt300@0: 		ofSetColor(0, 255, 0);
rt300@0: 	}else{
rt300@0:         ofSetLineWidth(1);
rt300@0: 		ofSetColor(0, 0, 255);
rt300@0: 	}
rt300@0:     
rt300@0: 	ofLine(sxpos, sypos, expos, eypos);
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: double Spring::getForceMag(){
rt300@0: 	return force.norm();
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: void Spring::addToScanPath(){
rt300@0: 	isInScanPath = true;
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: void Spring::removeFromScanPath(){
rt300@0: 	isInScanPath = false;
rt300@0: }
rt300@0: //---------------------------------------------------------------
rt300@0: /*
rt300@0: void Spring::checkStuff(){
rt300@0: 	cout << "checking\n";
rt300@0: }
rt300@0: */
rt300@0: PressureSpring::PressureSpring(){
rt300@0:     cout << "constructing a pressure spring for droplet mesh\n";
rt300@0: }
rt300@0: 
rt300@0: //---------------------------------------------------------------
rt300@0: TwoVector PressureSpring::getForce(Lump * aLump){ // pass in the lump that we want the force for
rt300@0:     
rt300@0:     // PRESSURE STUFF
rt300@0:     // by convention a positive pressure allways acts to the left as looking from start to end point
rt300@0:     // ie: Droplet MUST be constructed in clockwise fashion
rt300@0:     // we rotate the spring vector anti clockwise pi/2 radians this gives us the force vector
rt300@0:     // x = -y , y = x except damn y coordinate points downwards so handedness is reversed
rt300@0:     
rt300@0:     // conveniently this is proportional to length just as pressure would be
rt300@0:     //cout << "pressure spring get force\n";
rt300@0:     double xe = endPoint.x - startPoint.x;
rt300@0:     double ye = endPoint.y - startPoint.y;    
rt300@0: 	// above force refers to force at END force at START negative of this...
rt300@0: 	if(aLump ==  startLumpPtr){
rt300@0:         TwoVector rForce;
rt300@0:         rForce.setCoord(-force.x, -force.y);
rt300@0:         rForce.x += ye * globalForces.pressure * 0.5;
rt300@0:         rForce.y -= xe * globalForces.pressure * 0.5;
rt300@0:         return rForce;
rt300@0: 	}else if(aLump == endLumpPtr ){
rt300@0:         TwoVector rForce;
rt300@0:         rForce.setCoord(force.x, force.y);
rt300@0:         rForce.x += ye * globalForces.pressure * 0.5;
rt300@0:         rForce.y -= xe * globalForces.pressure * 0.5;
rt300@0:         return rForce;
rt300@0:     }
rt300@0:     cout << "PERROR this lump is not attached to this spring\n";
rt300@0:     
rt300@0: 	return force;
rt300@0: 	
rt300@0: }