Due to #6216, some of the reference examples related to cameras are broken.

[inaridarkfox4231]

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• Build Process
• Unit Testing
• Internalization
• Friendly Errors
• Other (specify if possible)

p5.js version

1.9.0

Web browser and version

Chrome

Operating System

Windows11

Steps to reproduce this

Steps:

1. use orbitControl() on reference page of ortho().
2. Then the object flies off somewhere.

https://p5js.org/reference/#/p5/ortho

Snippet:

//drag the mouse to look around!
//there's no vanishing point
function setup() {
  createCanvas(100, 100, WEBGL);
  ortho(-width / 2, width / 2, height / 2, -height / 2, 0, 500);
  describe(
    'two 3D boxes move back and forth along same plane, rotating as mouse is dragged.'
  );
}
function draw() {
  background(200);
  orbitControl();
  normalMaterial();

  translate(0,0,500);
  rotateX(0.2);
  rotateY(-0.2);
  push();
  translate(-15, 0, sin(frameCount / 30) * 65);
  box(30);
  pop();
  push();
  translate(15, 0, sin(frameCount / 30 + PI) * 65);
  box(30);
  pop();
}

2023-12-07.10-14-19.mp4

The cause is due to translate(). This causes the cube to be drawn far up in the sky, so when you rotate the camera around the viewpoint using orbitControl(), the object disappears from view.

In the current specifications, simply calling ortho() does not change the viewpoint position as it is initially set. In this case, it will remain at 800.

Value of eye without ortho():

So, for example, by setting the far value to 1000, you can prevent the object from disappearing.

2023-12-07.10-17-16.mp4

However, I can understand why they would want to do translate(0, 0, 500). I'm just guessing since I'm not involved.
Since it is a parallel projection, I think this indicates that the appearance does not change even if the drawing position moves up or down. Probably.
However, it is also true that because of this, orbitControl() actually behaves like a bug.
Therefore, I think some kind of modification is necessary, such as cutting orbitControl(). But I don't know what kind of fix it will be.

As suggested here, I am not suggesting that you should stop using translate() and set far to 1000. The problem is the unnatural behavior of orbitControl().
However, since there is no problem with orbitControl(), I think that some other modification is necessary.

In addition, it seems that a similar problem occurs with perspective().
https://p5js.org/reference/#/p5/perspective

I don't understand why the eyeZ default is uniformly 800. Previously, the value should have been based on the canvas size.
Looks like it was changed in #6216. I don't understand why this was allowed. It feels unnatural to always have 800. I don't understand.

After that, it seems that a change was made to #6549 to add this translate(0,0,500). However, because of this, orbitControl() has become a bug. Was this the right solution to do? I don't know.

[inaridarkfox4231]

Also, since eyeZ has become 800, the behavior of the default ortho() has become strange.

function setup() {
  createCanvas(400, 400, WEBGL);
  ortho();
  const cam = this._renderer._curCamera;
  console.log(cam.cameraFar);
  console.log(cam.eyeZ);
}

function draw() {
  orbitControl();
  background(220);
  box(100);
}

The reference page may have been able to do something with a band-aid solution, but should the ordinary user be asked to do the same? I think some kind of response is necessary. This is a bug no matter how you look at it.

[inaridarkfox4231]

The same goes for frustum().
https://p5js.org/reference/#/p5.Camera/frustum

The same goes for the first example of slerp(). This example was created taking into account that the viewpoint position is the previous version's position, so the behavior has changed significantly.
https://p5js.org/reference/#/p5.Camera/slerp

And nowhere in the reference is it stated that eyeZ defaults to 800 regardless of the canvas size. Why...

[inaridarkfox4231]

In summary, there are two points:

• In some examples, when orbitControl() is executed, objects disappear. There is no problem with the behavior of orbitControl(), so change the camera settings so that orbitControl() behaves naturally.
  https://p5js.org/reference/#/p5.Camera/perspective
  https://p5js.org/reference/#/p5.Camera/ortho
  https://p5js.org/reference/#/p5/frustum

• The behavior of the reference examples for slerp() and pan() is extreme because the viewpoint is in a high place (in the case of slerp(), only the first example). I think it would be better to return to the previous behavior by adjusting the camera position, for example.
  https://p5js.org/reference/#/p5.Camera/pan
  https://p5js.org/reference/#/p5.Camera/slerp

For example... for "perspective" example can be modify as:

// drag the mouse to look around!

let cam;

function setup() {
  createCanvas(100, 100, WEBGL);
  // create a camera
  cam = createCamera();
  cam.camera(0, 0, 50*sqrt(3), 0, 0, 0, 0, 1, 0);
  // give it a perspective projection
  cam.perspective(PI / 3.0, width / height, 0.1, 500);
}

function draw() {
  background(200);
  orbitControl();
  normalMaterial();

  rotateX(-0.3);
  rotateY(-0.2);

  push();
  translate(-15, 0, sin(frameCount / 30) * 35);
  box(30);
  pop();
  push();
  translate(15, 0, sin(frameCount / 30 + PI) * 35);
  box(30);
  pop();
}

[davepagurek]

And nowhere in the reference is it stated that eyeZ defaults to 800 regardless of the canvas size. Why...

I believe it says in here https://p5js.org/reference/#/p5/perspective, but putting this elsewhere too would be helpful.

I don't understand why the eyeZ default is uniformly 800. Previously, the value should have been based on the canvas size. Looks like it was changed in #6216. I don't understand why this was allowed. It feels unnatural to always have 800. I don't understand.

This was to address the issue that the camera position was updating inconsistently on window resize, since the camera distance from its target was, in part, defined by the aspect ratio of the window. Using a fixed distance removes the need to change the distance when the camera changes, and the perspective changes that happen when resizing a window. As you've noted, affects the near/far planes used, and existing behaviour.

I think to address the issues, we would either need to:

• Revert the change and add also handle updating the camera position whenever the window aspect ratio changes. This was initially not implemented because it gets complicated, but it is still an option if anyone is willing to work on it!
• Adjust the examples and ortho() and frustum() defaults to accommodate the default camera distance, and improve documentation

[davepagurek]

For orbit control flying away: I think that's because it orbits around the origin, and the translate() in the examples messes that up. maybe we need to remove the translation in the examples and change the near and far planes instead?

[inaridarkfox4231]

For orbit control flying away: I think that's because it orbits around the origin, and the translate() in the examples messes that up. maybe we need to remove the translation in the examples and change the near and far planes instead?

I agree. You can prevent objects from disappearing by increasing the far clip of the camera, so there is no need to use the translate() function. orbitControl() will also work correctly (but need to check, of course).

However, for reference examples such as pan(), I think it is better to move the camera eye position closer. If the viewpoint is (0,0,800) on a 100x100 canvas, the movement will be almost parallel, and it will be difficult to understand the behavior of shaking the camera left and right.

Another point I forgot to mention earlier is that the default far clip for ortho() has not been changed, so the object disappears when you run ortho() by default.
eyeZ is larger than camera's far clip

[inaridarkfox4231]

I just noticed that the example for the camera() function is also broken.

https://p5js.org/reference/#/p5/camera

The default values ​​listed here are wrong, right? It should be fixed at 800. I ran it and confirmed it.
It seems that the cause is that cameraNear is 80. Some modification will be necessary.

I have no objection to setting eyeZ's default to 800 across the board. However, I think we should have paid a little more attention to each area. Changing the default value is a breaking change. I think so.

[inaridarkfox4231]

I just took a quick look at it, and I see that most of the camera function examples are broken...I wonder why they didn't look into it properly.
https://p5js.org/reference/#/p5.Camera

In my opinion, resizing the camera is not a feature we always want. Therefore, shouldn't the impact on users who use camera ordinary be minimized? But I don't know what is the best thing to do. Because I haven't participated in the camera resizing discussion. Because I'm not interested.

[davepagurek]

Right, looks like a lot of the interactivity of the examples were missed.

I have no objection to setting eyeZ's default to 800 across the board. However, I think we should have paid a little more attention to each area. Changing the default value is a breaking change. I think so.

Yeah, it definitely is a behaviour change. It's always a balance between fixes that are perfectly backwards compatible, and fixes that are practical for contributors to implement. It's not always obvious ahead of time what the right balance is unfortunately, so we won't always get it right in retrospect.

In my opinion, resizing the camera is not a feature we always want. Therefore, shouldn't the impact on users who use camera ordinary be minimized? But I don't know what is the best thing to do. Because I haven't participated in the camera resizing discussion. Because I'm not interested.

Minimizing that impact makes sense, but also I think users generally want the camera view to not be stretched, so some amount of updating needs to happen. I've seen artists on Discord discussing how best to make their art responsive, so they need the resizing ability, and also need the view to be the same after resize + reload (so whatever position changes are imposed on load also have to happen on resize) and had to implement custom cameras before. None of you are wrong, all of it matters, but unfortunately it's a tough one to get fully correct.

It might mean that the best case scenario is to revert + try to find someone to invest the time into dealing with all the edge cases on resize when using fixed FoV rather than fixed distance.

[inaridarkfox4231]

I will summarize the problems.

broken examples

• p5.Camera, p5.Camera/pan
  Because the camera is too far away, the behavior is mostly parallel movement. It needs to make it easier to see that it is swinging from side to side by moving the camera closer.
• p5.Camera/tilt
  It has almost the same problem.
• p5.Camera/perspective, p5.Camera/ortho, p5.Camera/frustum
• perspective, ortho, frustum
  OrbitControl() does not work properly because of the translate() function. It needs to avoid using the translate() function. It will also need to make adjustments such as adjusting the far clip so that the object does not disappear.
• p5.Camera/camera, camera
  The object disappears because the near clip is 80. Clips need to be adjusted.
• setCamera, createCamera
  It might not be a bug, but the camera is too close or the object is zoomed in too much somehow.
  This may also be affected by the clip.
• p5.Camera/setPosition
  This may also be affected by the clip. Object disappear.
• p5.Camera/set
  This example also looks strange because it was created based on the previous version's perspective settings.
• p5.Camera/slerp
  The first example has the same problem as pan(). It needs to move the camera closer.
• debugMode, noDebugMode
  This also requires adjusting perspective(). The default appearance is strange.

Most of the problems with perspective() seem to be resolved by applying the previous settings as they are. Because it is designed with that in mind.

Problem with ortho() default settings

For example, if you run ortho() with no arguments on a 400x400 canvas, the object will disappear because the camera is too far away.

Measures such as adjusting the default value of farClip are required.

[inaridarkfox4231]

Probably most examples can be solved by applying one or both of the following: Applies to the global camera or default camera.

  camera(0, 0, 50*sqrt(3), 0, 0, 0, 0, 1, 0);
  perspective(PI/3, 1, 5*sqrt(3), 500*sqrt(3));

Because it was designed with that in mind. In any case, the current camera default settings are unnatural when drawing on a 100x100 canvas, so we have no choice but to return to the previous state.

current state:

  camera(0, 0, 800, 0, 0, 0, 0, 1, 0);
  perspective(PI/25.165, 1, 80, 8000);