Hi

I'm working on a similar problem and hitting the same snag.
modelX/Y/Z isn't suitable for that but it does work as specified. eg. saves x/y/z during a series of transform.

The issue is that there doesn't seem to be a straight forward way to get coordinates x/y from user input and translate it into x/y/z world space. All the code examples use an arbitrary Z.

the world space x/y/z doesn't change but it's easier to position things in relation to the camera centerX/y/z,
i.e. you get to see things.

I was having dificulty with the camera until I applyed a var c to both camera eye and center coordinates.




void setup(){
 size(200, 200, P3D);
 //noFill();
}

//a=mb+c
float a = 0.0;
float m = 0.0;
float b = 0.0;
float c = 0.0;

void draw(){
 background(204);
 //a=mb+c ->not used
 c = mouseY;
 //b =
 if(mousePressed){
   camera(width/2.0, height/1.0, -height/2.0+c,
   width/2.0, height/2.0, 0.0+c,
   0, -1, 0);
   b = -height/2.0+c;
 }
 else{
   m = b;
   camera(width/2.0, height/2.0, -height/2.0+m,
   width/2.0, height/2.0, 0.0+m,
   0, -1, 0);
 }

 pushMatrix();
 translate(width/2.0, height/2.0, 0);
 box(40);
 popMatrix();
 
 for(int i = 0; i<100; i++){

   line(0, height/2.0, (-height/2.0)+(i*20), width, height/2.0, (-height/2.0)+(i*20));

 }
}

unfortunately i think you are right.

i found a bug-ticket for this issue for release 135 (http://dev.processing.org/bugs/show_bug.cgi?id=486), saying its fixed.
but in version 1.01 it works only when NOT using camera(). but I need them both. any idea? (apart of tracking them all manually...)

below modified code form the API documentation:


// sh: camera vars
float ang = 0;
int max = 360;

void setup() {
 size(500, 500, P3D);
 noFill();
}

void draw() {
 background(0);
 
 // sh - added code
 // rotate camera
 float ra = 1500;
 
 float posX;
 float posY = -900;
 float posZ;
 float centX = 0;
 float centY = 130;
 float centZ = 0;
 
 posX = sin( radians(ang) ) * ra;
 posZ = cos( radians(ang) ) * ra;

 camera(posX, posY, posZ, centX, centY, centZ, 0, 1, 0 );

 ang += 0.05;
 ang = ( ang > max ) ? 0 : ang;

 // sh - end added code
 // code from API documentation

 pushMatrix();
 // start at the middle of the screen
 translate(width/2, height/2, -200);    
 // some random rotation to make things interesting
 rotateY(1.0); //yrot);
 rotateZ(2.0); //zrot);
 // rotate in X a little more each frame
 rotateX(frameCount / 100.0);
 // offset from center
 translate(0, 150, 0);

 // draw a white box outline at (0, 0, 0)
 stroke(255);
 box(50);

 // the box was drawn at (0, 0, 0), store that location
 float x = modelX(0, 0, 0);
 float y = modelY(0, 0, 0);
 float z = modelZ(0, 0, 0);
 // clear out all the transformations
 popMatrix();

 // draw another box at the same (x, y, z) coordinate as the other
 pushMatrix();
 translate(x, y, z);
 stroke(255, 0, 0);
 box(50);
 popMatrix();
}