bjordal has helped me with an algorithm to draw lines using dots only. Original Thread https://forum.processing.org/topic/how-to-draw-a-line-with-just-dots

Here is what I have done with it so far. I would like someone to indicate how I can use it to draw 3D lines. I can draw the lines down the z-axis once either the x or y values are constant  however I have an idea of using a ratio method to draw the lines but I am having difficulty implementing it

Here is a screenshot


Here is the code
Press 'v' to toggle between PeasyCam use and no camera (default) 

Hint : in the event you do not have the peasycam library just comment the line referring to the PeasyCam library and .... >>   // cam = new PeasyCam (this , width);

1. import peasy.org.apache.commons.math.*;
   import peasy.*;
   import peasy.org.apache.commons.math.geometry.*;
   PeasyCam cam;
   GL gl;
   PGraphicsOpenGL pgl;
   boolean click = false;
   import processing.opengl.*;
   import javax.media.opengl.*;
   public String rmode = "P3D";
   public float factor = 1.5;
   public float shf=0f;
   public float bam=0f;
   public boolean viewpeasy = false;
   void setup(){
   
     shf= .75;
     if(rmode=="OPENGL")size(255,255,OPENGL);
     if(rmode=="P3D")size(255,255,P3D);
   
     frameRate(3000);
     lights();
     // hint (DISABLE_DEPTH_TEST);
     hint(DISABLE_OPENGL_2X_SMOOTH);
     hint(ENABLE_OPENGL_4X_SMOOTH);
     if (rmode == "OPENGL"){
       pgl = (PGraphicsOpenGL) g;
       gl = pgl.gl;
       gl.glHint (gl.GL_LINE_SMOOTH_HINT, gl.GL_NICEST);
       gl.glEnable (gl.GL_LINE_SMOOTH);
     }
     if (rmode == "P3D"){
       smooth();
     }
     if(rmode=="P3D")strokeWeight(1.3);
     if(rmode=="OPENGL")strokeWeight(1.6);
     if(viewpeasy)cam = new PeasyCam (this,width);
   }
   public float depth = 255*factor;
   void draw(){
   
     if(viewpeasy )  {
   
       cam = new PeasyCam (this,width);
   
       translate(-width/2,-height/2);
     }
     //if (!viewpeasy)cam = null;
     background(-1);
     boolean fs = false;
     if (fs==true){
       translate(width/2,height/2,-depth/2);
       stroke(1,41);
       noFill();
       // noSmooth();
       sphere(23);
       // smooth();
       translate(-width/2,-height/2,depth/2);
   
       stroke(1);
     }
     square();
     dl2(width/2,25,width/2,height-25);
     translate(0,0,-depth);
     dl3z(mouseX,mouseY,depth);
     square();
     dl2(width/2,25,width/2,height-25);
   
     dl3z(width/2,height-25,depth);
     dl3z(width/2,25,depth);
   
     dl3z(25,25,depth);
     dl3z(width-25,25,depth);
     dl3z(25,height-25,depth);
     dl3z(width-25,height-25,depth);
     dl3z(width/2,mouseY,depth);
     if (mousePressed)atsq(mouseX,mouseY,30,30);
     if(!mousePressed)atsq(mouseX,mouseY,33,33);
     _dl3(width/2,25,width/2,mouseY);
     dl3z(mouseX,mouseY,depth/2);
     translate(0,0,depth);
     if (mousePressed)atsq(mouseX,mouseY,30,30);
     if(!mousePressed)atsq(mouseX,mouseY,33,33);
   
     translate(width/2,height/2,-depth/2);
     // noStroke();
     noFill();
     stroke(1,41);
     // noSmooth();
     sphere(23);
     // smooth();
     translate(-width/2,-height/2,depth/2);
     noFill();
     stroke(1);
   
   }
   
   void square(){
     dl2(25,25,width-25,25);
     dl2(25,height-25,25,25);
     dl2(width-25,25,width-25,height-25);
     dl2(25,height-25,width-25,height-25);
   
   }
   
   void dl(float x1,float y1,float x2,float y2){
     float angle = atan2(y2-y1,x2-x1);
     float currentX = x1;
     float currentY = y1;
     while(abs(currentX-x2) > abs(cos(angle))){
   
       pointx(currentX,currentY);
       currentX += cos(angle);
       currentY += sin(angle);
     }
   }
   
   
   //EDIT: this is more of the graph way of doing it - it is (as far as i can tell) faster but not as accurate
   
   
   //Copy code
   void dl3z(float x1,float y1,float deep){
     for (float z =0;z<deep;z+=1){
       // translate(x1,y1,z);
       pointz(x1,y1,z);
       //translate(x1,y1,-z);
     }
   
   }
   
   void dl2z(float x1,float y1,float x2,float y2){
     float dx = x2-x1;
     float dy = y2-y1;
     if(dx == 0){
       for(float i = min(y1,y2);i<max(y1,y2);i+=1){
         translate(0,0,-i);
         pointx(x1,x1);//i
         translate(0,0,i);
       }
       return;
     }
     float k = dy/dx;
     float m = y1 -x1*k;
     for(float i = min(x1,x2);i<max(x1,x2);i+=1/max(1,abs(k))){
       translate(0,0,-i);
       // pointx(i,k*i+m);
       pointx(i,k);
       translate(0,0,i);
     }
   }
   
   
   void dl2(float x1,float y1,float x2,float y2){
     float dx = x2-x1;
     float dy = y2-y1;
     if(dx == 0){
       for(float i = min(y1,y2);i<max(y1,y2);i+=1){
         point(x1,i);
       }
       return;
     }
     float k = dy/dx;
     float m = y1 -x1*k;
     for(float i = min(x1,x2);i<max(x1,x2);i+=1/max(1,abs(k))){
       pointx(i,k*i+m);
     }
   }
   
   void pointx(float x,float y){
   
     if(rmode=="P3D")  point(x,y);
     if(rmode=="OPENGL") line(x,y,x+1,y);
   }
   void pointz(float x,float y,float z){
   
     if(rmode=="P3D")point(x,y,z);
     if(rmode=="OPENGL")line(x,y,z,x,y,z+1);
   }
   
   void atsq(float x,float y, float w,float h){
     float c1 = x-w/2;
     float c2= y-h/2;
     dl2(c1,c2,c1+w,c2);
     dl2(c1,c2,c1,c2+h);
     dl2(c1+w,c2,c1+w,c2+h);
     dl2(c1,c2+h,c1+w,c2+h);
   
   }
   
   void _dl2(float x1,float y1,float x2,float y2){
     float dx = x2-x1;
     float dy = y2-y1;
     if(dx == 0){
       for(float i = min(y1,y2);i<max(y1,y2);i+=1){
         pointz(x1,i,i*factor);
       }
       return;
     }
     float k = dy/dx;
     float m = y1 -x1*k;
     for(float i = min(x1,x2);i<max(x1,x2);i+=1/max(1,abs(k))){
       pointz(i,k*i+m,(k*i+m)*factor);
     }
   }
   
   void _dl3(float x1,float y1,float x2,float y2){
     bam = 0;
     float dx = x2-x1;
     float dy = y2-y1;
     if(dx == 0){
       for(float i = min(y1,y2);i<max(y1,y2);i+=1){
         bam +=shf;
         pointz(x1,i,i+bam);
       }
       return;
     }
     bam=0;
   
     float k = dy/dx;
     float m = y1 -x1*k;
     for(float i = min(x1,x2);i<max(x1,x2);i+=1/max(1,abs(k))){
       bam +=shf;
       pointz(i,k*i+m,(k*i+m)+bam);
     }
   }
   
   void keyPressed(){
     if (key=='v'){
       viewpeasy= !viewpeasy;
       //setup();
     }
   }