Can you call set_fills() more than once on a Py5Shape object?

[villares]

Season's greetings!

Am I doing something wrong? It looks like something happens after a call to .set_fills(). Maybe Py5Shape objects get tired after a long year? 😄

Maybe something fun to investigate in 2025!

import py5
import numpy as np

def setup():
    global icosa
    py5.size(600, 600, py5.P3D)
    icosa = icosahedron(250)    
    icosa.set_fills(random_color() for _ in range(60))

def draw():
    py5.background(0)
#     if py5.frame_count > 100:
#         icosa.set_fills(random_color() for _ in range(60))
    py5.translate(py5.width / 2, py5.height / 2)
    py5.shape(icosa, 0, 0)

def random_color():
    return py5.color(py5.random_int(255), py5.random_int(255), py5.random_int(255))

def key_pressed():
    print(py5.key)
    if py5.key == 'a':
        icosa.set_fills(random_color() for _ in range(60))
    elif py5.key == 'b':
        icosa.set_fill(random_color())

def icosahedron(radius):
    global vs, sequence
    f = (radius / 2) # / 0.95 # aprox. ?
    phi = (py5.sqrt(5) + 1) / 2
    a = phi * f
    b = 1 * f
    vs = np.array([
        (a,  b,  0),
        (a,  -b,  0),
        (-a,  -b,  0),
        (-a,  b,  0),
        (b,  0, a),
        (-b,  0, a),
        (-b,  0, -a),
        (b, 0, -a),
        (0, a, b),
        (0, a, -b),
        (0, -a, -b),
        (0, -a, b),
    ])
    sequence = np.array([
        2, 11, 5, 2, 5, 3, 5, 8, 3, 4, 8, 5, 11, 4, 5,
        10, 2, 6, 2, 3, 6, 3, 9, 6, 3, 8, 9, 2, 10, 11,
        1, 4, 11, 1, 0, 4, 7, 0, 1, 10, 1, 11, 0, 8, 4,
        0, 9, 8, 7, 9, 0, 1, 10, 7, 10, 6, 7, 6, 9, 7,  
    ])
    shp = py5.create_shape()
    shp.begin_shape(py5.TRIANGLES)
    shp.vertices(vs[sequence])
    shp.end_shape()
    return shp

py5.run_sketch(block=False)

[vsquared]

You probably already know this, but the following works on my mac. To get it to run I had to add a def settings(): to setup the window and set blocking to True. For some reason icosa is not recognized by key_pressed(): as being a global which I don't understand since draw(): seems to recognize it. By defining icosa a second time inside of key_pressed() it seems to fix it:

import py5
import numpy as np

def settings():
    py5.size(600, 600, py5.P3D)
    
def setup():
    global icosa
    icosa = icosahedron(250)    
    icosa.set_fills(random_color() for _ in range(60))

def draw():
    py5.background(0)
    py5.translate(py5.width / 2, py5.height / 2)
    py5.shape(icosa, 0, 0)

def random_color():
    return py5.color(py5.random_int(255), py5.random_int(255), py5.random_int(255))

def key_pressed():
    global icosa;
    print(py5.key)
    if py5.key == 'a':
        icosa = icosahedron(250) 
        icosa.set_fills(random_color() for _ in range(60))
    elif py5.key == 'b':
        icosa.set_fill(random_color())

def icosahedron(radius):
    global vs, sequence
    f = (radius / 2) # / 0.95 # aprox. ?
    phi = (py5.sqrt(5) + 1) / 2
    a = phi * f
    b = 1 * f
    vs = np.array([
        (a,  b,  0),
        (a,  -b,  0),
        (-a,  -b,  0),
        (-a,  b,  0),
        (b,  0, a),
        (-b,  0, a),
        (-b,  0, -a),
        (b, 0, -a),
        (0, a, b),
        (0, a, -b),
        (0, -a, -b),
        (0, -a, b),
    ])
    sequence = np.array([
        2, 11, 5, 2, 5, 3, 5, 8, 3, 4, 8, 5, 11, 4, 5,
        10, 2, 6, 2, 3, 6, 3, 9, 6, 3, 8, 9, 2, 10, 11,
        1, 4, 11, 1, 0, 4, 7, 0, 1, 10, 1, 11, 0, 8, 4,
        0, 9, 8, 7, 9, 0, 1, 10, 7, 10, 6, 7, 6, 9, 7,  
    ])
    shp = py5.create_shape()
    shp.begin_shape(py5.TRIANGLES)
    shp.vertices(vs[sequence])
    shp.end_shape()
    return shp

py5.run_sketch(block=True)

[villares]

Cheers @vsquared!

On my yesterday's sketch-a-day I did this as a workaround... recreating the Py5Shape object on each frame :)

You needed the global statement in key_pressed() because you were doing a new assignment on the global name icosa, in draw() you are just "reading" the variable, so there is no need to add global. This was one of the trickiest things for me coming from Java to Python.

On MacOS the conventional Python interpreter won't let you set block=False :(

[hx2A]

I just tried running this. I believe it might be a Processing bug where once the shape is drawn to the screen, Processing's PShapeOpenGL method setFill(int index, int fill) (which is what py5 calls in a loop when you call Py5Shape's set_fills() method) does not let you update the shape. Can you try testing it to see? From looking at Processing's source, I see that Processing's setFill() and setFills() behave a bit differently if the shape has been tesselated (this happens when it is rendered to the screen for the first time).

[villares]

Is setFills() undocumented or "internal only" in Processing? I could only find setFill() https://processing.org/reference/PShape.html 😕

setFill() (and equivalent set_fill() in py5) can be called and work as expected (making all fill the same).

PShape shp;

void setup(){
  size(300, 300, P3D);
  shp = createShape();
  shp.beginShape(TRIANGLES);
  shp.vertex(100, 100);
  shp.vertex(200, 100);
  shp.vertex(100, 200);
  shp.vertex(200, 200);
  shp.vertex(200, 100);
  shp.vertex(100, 200);
  shp.endShape();
}

void draw(){
  shp.setFill(color(random(255), 200, 0));
  shape(shp);
}

[hx2A]

Sorry, setFills() is a py5 addition. Processing doesn't have it.

The source for setFills() is basically a for loop:

      for (int i = 0; i < fills.length; ++i) {
        s.setFill(i, fills[i]);
      }

So to test it, you'd basically need compare PShape.setfill(color) with PShape.setfill(i, color) where i is a for loop.

[vsquared]

The following Processing code demonstrates a PShape array for the sides of a cube and then using a 'for' loop to change each side's color with the setFills() code shown above.

// Reference for cube:
//https://stackoverflow.com/questions/72270464/how-to-draw-a-cube-in-processing-without-the-box-function

PShape cube;
PShape[] sides = new PShape[6];
color[] fills = new color[6];

void setup() {
  size(600, 600, P3D);
  surface.setTitle("Press mouse to change colors.");
  strokeWeight(3);
  for (int i = 0; i < fills.length; ++i) {
    fills[i] = color(random(255), random(255), random(255));
  }
  cube = createShape(GROUP);
  cubeSides(150);
}

void draw() {
  background(255);
  translate(width/2, height/2, 0);
  rotateY(map(mouseX, 0, width, -PI, PI));
  rotateX(map(mouseY, 0, height, PI, -PI));
  shape(cube);
}

void cubeSides(float size) {
  // half size: keep the pivot at the center
  float s = size * 0.5;
  // back (-z)
  sides[0] = createShape();
  sides[0].beginShape();
  sides[0].fill(fills[0]);
  sides[0].vertex(-s, -s, -s);
  sides[0].vertex(+s, -s, -s);
  sides[0].vertex(+s, +s, -s);
  sides[0].vertex(-s, +s, -s);
  sides[0].endShape();
  // front (+z)
  sides[1] = createShape();
  sides[1].beginShape();
  sides[1].fill(fills[1]);
  sides[1].vertex(-s, -s, +s);
  sides[1].vertex(+s, -s, +s);
  sides[1].vertex(+s, +s, +s);
  sides[1].vertex(-s, +s, +s);
  sides[1].endShape();
  // top (-y)
  sides[2] = createShape();
  sides[2].beginShape();
  sides[2].fill(fills[2]);
  sides[2].vertex(-s, -s, +s);
  sides[2].vertex(-s, -s, -s);
  sides[2].vertex(+s, -s, -s);
  sides[2].vertex(+s, -s, +s);
  sides[2].endShape();
  // bottom (+y)
  sides[3] = createShape();
  sides[3].beginShape();
  sides[3].fill(fills[3]);
  sides[3].vertex(+s, +s, +s);
  sides[3].vertex(+s, +s, -s);
  sides[3].vertex(-s, +s, -s);
  sides[3].vertex(-s, +s, +s);
  sides[3].endShape();
  // left (-x)
  sides[4] = createShape();
  sides[4].beginShape();
  sides[4].fill(fills[4]);
  sides[4].vertex(-s, -s, +s);
  sides[4].vertex(-s, -s, -s);
  sides[4].vertex(-s, +s, -s);
  sides[4].vertex(-s, +s, +s);
  sides[4].endShape();
  // right (+x)
  sides[5] = createShape();
  sides[5].beginShape();
  sides[5].fill(fills[5]);
  sides[5].vertex(+s, -s, +s);
  sides[5].vertex(+s, -s, -s);
  sides[5].vertex(+s, +s, -s);
  sides[5].vertex(+s, +s, +s);
  sides[5].endShape();
  
  cube.addChild(sides[0]);
  cube.addChild(sides[1]);
  cube.addChild(sides[2]);
  cube.addChild(sides[3]);
  cube.addChild(sides[4]);
  cube.addChild(sides[5]);
}

void mousePressed() {
  // Py5 set_fills() code:
  for (int i = 0; i < fills.length; ++i) {
    fills[i] = color(random(255), random(255), random(255));
    sides[i].setFill(fills[i]);
  }
}

Py5 version:
Uses set_fill() in a 'for' loop. set_fills() apparently requires numpy which I am not familiar with. Requires Imported mode for py5.

sides = []
fills = []

def setup():
  global cube;
  size(600, 600, P3D)
  window_title("Press mouse to change colors.")
  stroke_weight(3)
  for i in range(6):
      fills.append(color(random(255),random(255),random(255)))
  cube = create_shape(GROUP)
  cubeSides(150)

def draw():
  background(255)
  translate(width/2, height/2, 0)
  rotate_y(remap(mouse_x, 0, width, -PI, PI))
  rotate_x(remap(mouse_y, 0, height, PI, -PI))
  shape(cube)

def cubeSides(size):
  global sides
  global fills
  global cube
#    half size: keep the pivot at the center
  s = size * 0.5;
  for i in range(6):
    sides.append(create_shape())
#    back (-z)
  sides[0].begin_shape()
  sides[0].fill(fills[0])
  sides[0].vertex(-s, -s, -s)
  sides[0].vertex(+s, -s, -s)
  sides[0].vertex(+s, +s, -s)
  sides[0].vertex(-s, +s, -s)
  sides[0].end_shape()
#    front (+z)
  sides[1].begin_shape()
  sides[1].fill(fills[1])
  sides[1].vertex(-s, -s, +s)
  sides[1].vertex(+s, -s, +s)
  sides[1].vertex(+s, +s, +s)
  sides[1].vertex(-s, +s, +s)
  sides[1].end_shape()
#    top (-y)
  sides[2].begin_shape();
  sides[2].fill(fills[2])
  sides[2].vertex(-s, -s, +s)
  sides[2].vertex(-s, -s, -s)
  sides[2].vertex(+s, -s, -s)
  sides[2].vertex(+s, -s, +s)
  sides[2].end_shape()
#    bottom (+y)
  sides[3].begin_shape()
  sides[3].fill(fills[3])
  sides[3].vertex(+s, +s, +s)
  sides[3].vertex(+s, +s, -s)
  sides[3].vertex(-s, +s, -s)
  sides[3].vertex(-s, +s, +s)
  sides[3].end_shape()
#    left (-x)
  sides[4].begin_shape()
  sides[4].fill(fills[4])
  sides[4].vertex(-s, -s, +s)
  sides[4].vertex(-s, -s, -s)
  sides[4].vertex(-s, +s, -s)
  sides[4].vertex(-s, +s, +s)
  sides[4].end_shape()
#    right (+x)
  sides[5].begin_shape()
  sides[5].fill(fills[5])
  sides[5].vertex(+s, -s, +s)
  sides[5].vertex(+s, -s, -s)
  sides[5].vertex(+s, +s, -s)
  sides[5].vertex(+s, +s, +s)
  sides[5].end_shape()

  cube.add_child(sides[0])
  cube.add_child(sides[1])
  cube.add_child(sides[2])
  cube.add_child(sides[3])
  cube.add_child(sides[4])
  cube.add_child(sides[5])

def mouse_pressed():
  for i in range(6):
      sides[i].set_fill(color(random_int(255), random_int(255), random_int(255)))

[hx2A]

No, set_fills() should work fine on a 3D object. There must be a bug where it doesn't work after the shape is drawn to the screen for the first time.

set_fills() won't work on a group shape though. You'd need to call it for each of the child shapes and have the correct number of fills, which will equal the number of vertices. Each vertex has its own fill color.

[vsquared]

I tried that and couldn't get it to work (but it doesn't crash):

def mouse_pressed():
  for child in cube.get_children():
      child.set_fills(color(random(255),random(255),random(255)) for _ in range(4))

If I use range(6) which is the number of faces, I get this:

[hx2A]

I tried that and couldn't get it to work (but it doesn't crash):

Right, it doesn't work. That's the bug. After the shape is drawn to the screen, set_fills() can no longer change the vertex fills.

You could use set_fill() and set the child object to a new (single) fill color. That works.

If I use range(6) which is the number of faces, I get this:

You should use range(4) there because each child shape (each face of the cube) has 4 vertices. Six is the number of cube faces or the number of children in cube.

[vsquared]

You could use set_fill() and set the child object to a new (single) fill color. That works.
Correct. That's why I don't think you need set_fills(), but that's just my opinion. If someone can produce a workable 3D multifaceted demo I could change my mind. Even that apparently precludes iterating solid colors for the faces which would still require set_fill() in a 'for' loop.
Question:
If set_fills() is calling set_fill() in a 'for' loop behind the curtain and set_fill() with a 'for' loop works by itself then why doesn't set_fills() work as expected? Things must not be what they seem behind the curtain.

[hx2A]

Correct. That's why I don't think you need set_fills(), but that's just my opinion.

Right, it isn't useful for this case. It isn't useful for a lot of things outside of what it was created for, which is helping py5 convert Trimesh objects to Py5Shape objects. And that it does very well.

If set_fills() is calling set_fill() in a 'for' loop behind the curtain and set_fill() with a 'for' loop works by itself then why doesn't set_fills() work as expected?

py5's set_fills() calls Processing's setFill(int index, int color) in a for loop, which has a different implementation than Processing's setFill(int color). Processing's setFill(int color) does not call Processing's setFill(int index, int color) in a for loop. The differences are an important clue about why it isn't working.

[vsquared]

Alternate way of using setFills() more than once:

# Uses Imported mode for py5

def drawMyCube():
  global cube
  cube = create_shape()
  s = 75
  cube.begin_shape(QUADS)
# back (-z)
  cube.vertex(-s, -s, -s)
  cube.vertex(+s, -s, -s)
  cube.vertex(+s, +s, -s)
  cube.vertex(-s, +s, -s)
# front (+z)  
  cube.vertex(-s, -s, +s)
  cube.vertex(+s, -s, +s)
  cube.vertex(+s, +s, +s)
  cube.vertex(-s, +s, +s)
# top (-y)
  cube.vertex(-s, -s, +s)
  cube.vertex(-s, -s, -s)
  cube.vertex(+s, -s, -s)
  cube.vertex(+s, -s, +s)
# bottom (+y)
  cube.vertex(+s, +s, +s)
  cube.vertex(+s, +s, -s)
  cube.vertex(-s, +s, -s)
  cube.vertex(-s, +s, +s)
# left (-x)
  cube.vertex(-s, -s, +s)
  cube.vertex(-s, -s, -s)
  cube.vertex(-s, +s, -s)
  cube.vertex(-s, +s, +s)
# right (+x)
  cube.vertex(+s, -s, +s)
  cube.vertex(+s, -s, -s)
  cube.vertex(+s, +s, -s)
  cube.vertex(+s, +s, +s)
  cube.end_shape()
  cube.set_fills(color(random(255),random(255),random(255)) for _ in range(24))

def setup():
  size(600, 600, P3D)
  window_title("Rotate with mouse click to change colors.")
  stroke_weight(3)
  drawMyCube()

def draw():
  background(209)
  translate(width/2, height/2, 0)
  rotate_x(remap(mouse_y, 0, height, PI, -PI))
  rotate_y(remap(mouse_x, 0, width, -PI, PI))
  shape(cube)

def mouse_pressed():
  drawMyCube()  

Output:

[villares]

There is a mention to an update() method for PShape at https://processing.github.io/processing-javadocs/core/processing/core/PShape.html, but I couldn't find it.

If I have the time and energy I might investigate PShapeOpenGL https://processing.github.io/processing-javadocs/core/processing/opengl/PShapeOpenGL.html that can be instantiated from a PShape, it seems... I wonder if it would be an expensive operation to "copy" a pristine PShape into something I would then colorize.

[hx2A]

If I have the time and energy I might investigate PShapeOpenGL https://processing.github.io/processing-javadocs/core/processing/opengl/PShapeOpenGL.html that can be instantiated from a PShape, it seems... I wonder if it would be an expensive operation to "copy" a pristine PShape into something I would then colorize.

PShapeOpenGL is an ugly mess. There is "pre-tessellated" geometry, which is the result of the Processing method calls, and is understandable and readable. This gets converted to tessellated geometry, and that's what actually gets sent to OpenGL to be rendered. That part is confusing and I understand very little of it, despite many efforts to figure it out.

It's the tessellated geometry that needs to get refreshed if you want set_fills() to change the colors after the shape is drawn to the screen (which is when tessellation happens).

[vsquared]

The Processing runtime code was changed: (processing/processing4#677)
setFill(indx,color) used to work correctly, but no longer does.

[hx2A]

One of the Processing teams' priorities for 2025 is to make unit tests, which would help prevent this kind of bug from happening in the future.

[vsquared]

I resubmitted a bug report to go along with the one approximately a year ago.

The following may or may not be important. It was committed 5 yr. ago and is over 5000 lines of code:
https://github.com/processing/processing/blob/master/core/src/processing/opengl/PShapeOpenGL.java