In P3D, the rendered and rotated ellipse at mouse position is hidden by half of another shape

ITISLTW

Both ellipse and rectangle plane have same rotation, and ellipse's z index is 1 higher than rectangle's. The wired thing is when the mouse position is below the rectangle's y position, the ellipse will be hidden behind the rectangle.

This trobules me a lot, anyone has a good idea?

Here is the code.

void setup() {
  frameRate(60);
  size(1000, 1000, P3D);
  smooth(6);
}

void draw() {
  background(120);

  pushMatrix();
  pushStyle();
  noStroke();
  translate(width/2, height/2, 0);
  rotateX(1);
  rectMode(CENTER);
  rect(0, 0, 800, 800);
  fill(0);
  textAlign(CENTER, CENTER);
  textSize(120);
  text("TEST", 0, 0, 1);
  popStyle();
  popMatrix();

  pushMatrix();
  pushStyle();
  translate(mouseX, mouseY, 1);
  rotateX(1);
  fill(0);
  ellipse(0, 0, 50, 50);
  popStyle();
  popMatrix();

}

Thanks

kfrajer

Edit your post (gear icon in the top right corner of your post), select your code and hit ctrl+o to format your code. Make sure there is an empty line above and below your code.

Kf

kfrajer

On top of the surface.... but the mouse pointer does not map the ellipse due to the transformation.

NOTE: You get the same effect if you remove the second push/pop matrix in your code and add this line right after your "test" in text():

ellipse(mouseX-width/2,mouseY-height/2, 50, 50);

Kf

void setup() { 
  frameRate(60); 
  size(1000, 1000, P3D); 
  smooth(6);

  rectMode(CENTER);  
  textAlign(CENTER, CENTER); 
  textSize(120);
}

void draw() { 
  background(120);

  pushMatrix(); 
  pushStyle(); 
  noStroke(); 
  translate(width/2, height/2, 0); 
  rotateX(1); 
  fill(255);
  rect(0, 0, 800, 800);
  fill(0);
  text("TEST", 0, 0, 1); 
  popStyle(); 
  popMatrix();

  pushMatrix(); 
  pushStyle(); 
  translate(mouseX, mouseY, tan(1)*(mouseY-height/2)+1); 
  rotateX(1); 
  fill(0); 
  ellipse(0, 0, 50, 50); 
  popStyle(); 
  popMatrix();
}

ITISLTW

@kfrajer Thanks for your reply. After the modification as what you said, the ellipse is at the position differing from the mouse pointer. I tried noCursor() to hide cursor to make it not wired, but it will stop after the mouse pointer is out of the screen.

I am building an isomatic game in which the cursor plays a role of 3d navigation cursor to conduct where the player goes. This is the reason why do I need to keep the rendered ellipse and mouse pointer at same position under 3D rotation.

I tried ortho() to make the game isomatric, but it is pretty wired and different from the standard of isomatrics from other 3D software I've tested.

If you have any good idea or functions I can use, please tell me Thanks

kfrajer

Yes, I was trying to do the projection of the mouse to the rotated plane. Less trivial as you need to take into account the camera position

So, I cannot continue on this atm... I suggest exploring

https://forum.processing.org/two/search?Search=raytracing

Specifically:

https://forum.processing.org/two/discussion/21644/picking-in-3d-through-ray-tracing-method/p1

If you don't make it work, please reply below and I can give it a try at a later time or other forum members will be able to assist more.

Kf

ITISLTW

@kfrajer Thank you, this information is helpful. I tried their code and successed. Now I am going to learn it and create new one

kfrajer

Great to hear. Good luck!

Kf