How to rotate a box in 3D around one edge

General Discussion Other

michaelhe..

How to rotate a box in 3D around one edge

in General Discussion • Other • 1 year ago

Hi,

I want to rotate a box around one corner, like if you roll a die. And I want to do it at an arbitrary position in space.

Maybe one can imagine a cuboid like a cupboard which I want to translate first from the center of a room (coordinates 0,0,0) to one corner and than (e.g. standing behind) pushing the cupboard in a way that it is tilting and falling on its doors (I hope the example makes it clear).

I tried several combinations of translate and rotate but didn't catch how to do it. Is anybody out there how knows how to do such a kind of rotation?

Thanks in advance

Michael

Replies(7)

PhiLho

Re: How to rotate a box in 3D around one edge

1 year ago

Several examples at http://processing.org/learning/3d/ show rotating cubes. Perhaps studying their code can help.

michaelhe..

Re: How to rotate a box in 3D around one edge

1 year ago

The examples don't help me since all rotations are more or less "uncontrolled".

carstentr

Re: How to rotate a box in 3D around one edge

1 year ago

" I tried several combinations of translate and rotate ...

Did you try:

Translate the rotationPoint (and the appenede box) to (0,0,0)

Rotate

Translate back

michaelhe..

Re: How to rotate a box in 3D around one edge

1 year ago

Well, I tried something like this:

void setup()
{
size(400,400,P3D);
smooth();
    noStroke();
}

void draw()
{
background(255);

camera(0,0,700,
         0,0,0,
         0,1,0);

// Box to rotate around lower left
// edge and to place with this edge
// at defined position
pushMatrix();
fill(100,100,100);
box(100,200,10);
popMatrix();

// Hand-made solution
pushMatrix();
fill(150,150,150);
rotateZ(-PI/8.);
translate(175,118,0);
box(100,200,10);
popMatrix();

// mark space-zero
pushMatrix();
fill(200,0,0);
box(10,10,10);
popMatrix();

// target for the rotated lower left edge
pushMatrix();
fill(20,20,255);
translate(200,150,0);
box(10,10,10);
popMatrix();
}

but since the transformation after rotation works along the new coordinate axes
it seems that one has to calculate the translation by hand which I definitely
want to avoid.

michaelhe..

Re: How to rotate a box in 3D around one edge

1 year ago

Here is what I want to get but in 2D:

float angle=0;
void setup()
{
size(400,400);
noStroke();
}

void draw()
{
background(255);

pushMatrix();

translate(200,200);

// define original
fill(100);
rect(0, 0, 40, 40);

// define zero
fill(0);
rect(-2, -2, 4, 4);

// rect with the desired rotation
angle += 1;
rotate(radians(angle));
fill(150);
rect(0, 0, 40, 40);
popMatrix();
}

This works easily since in 2D one can place a rectangle
at an arbitrary position in space. In 3D the box is always
placed at (0,0,0).

michaelhe..

Re: How to rotate a box in 3D around one edge

1 year ago

Hmmm ... currently I don't really understand it but I found the solution.
I've only to unscramble my brain to understand what I did (should be possible).
Here is what I wanted to do:

import processing.opengl.*;
float angle=0.;
void setup()
{
size(400,400,OPENGL);
smooth();
}

void draw()
{
background(255);

camera(400,-200,700,
0,0,0,
0,1,0);

// coordinate system
fill(255,0,0);
box(100,5,5);
fill(0,255,0);
box(5,100,5);
fill(0,0,255);
box(5,5,100);

// Box to rotate around lower left
// edge and to place with this edge
// at defined position
pushMatrix();
fill(150,150,150);

translate(200,150,0);
angle += 1.;
rotateZ(radians(-angle));
translate(-10,100,0);

box(20,200,100);
popMatrix();

// target for the rotated lower left edge
pushMatrix();
fill(20,20,255);
translate(200,150,0);
box(10,10,10);
popMatrix();
}

keyadding

Re: How to rotate a box in 3D around one edge

1 year ago

Is there anyone know this? I want to get the answer too.

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