problem with constraint inside a constructor

Programming Questions

lwerber

problem with constraint inside a constructor

in Programming Questions • 2 years ago

I have an array of Stamp objects and each time the mouse is clicked a new Stamp object is added to the array. I have mouseX and mouseY positions as arguments for the constructor so that the new object is created where ever the mouse is. I also have a void mouseDragged function setup so that when SHIFT is pressed and the mouse is dragged the user can translate the origin left and and right. To account for this the object also takes moveX and moveY (variables I created to store the current origin coordinates) as arguments, which are subtracted from the mouseX and mouseY coordinates. This was working fine until I tried to constrain the x and y position a circular area of the page. Now when the origin is translated the constraint is keeping the object constrained to the same circular area.

Is there a problem with using a constraint inside a constructor?

Here is the code for the constructor (tempX and tempY are the mouseX and Y position at the time of the stamp objects creation and and temp_moveX and temp_moveY are the coordinates of the origin at the time of the stamps creation) :

Stamp(float tempX, float tempY, float temp_moveX, float temp_moveY, float temp_moveZ) {
    currentMoveX = temp_moveX;
    currentMoveY = temp_moveY;
    currentMoveZ = temp_moveZ;
    hypotenuse = dist(temp_moveX, temp_moveY, tempX, tempY);
    side1 = tempX-temp_moveX;
    side2 = tempY-temp_moveY;
    angle = acos((sq(side2)-sq(hypotenuse)-sq(side1)) / (-2*hypotenuse*side1));
    x = constrain(tempX - currentMoveX, -(abs(130 * cos(angle))), abs(130 * cos(angle)));
    y = constrain(tempY - currentMoveY, -(abs(130 * sin(angle))), abs(130 * sin(angle)));
}

THANK YOU!

Replies(3)

PhiLho

Re: problem with constraint inside a constructor

2 years ago

" Is there a problem with using a constraint inside a constructor?"
Not at all, that's just some math.
Perhaps you should double-check your math... I admit I don't understand what you are trying to do with it, particularly with the 130 constant... (should be a true constant, not a literal)

lwerber

Re: problem with constraint inside a constructor

2 years ago

Thanks for your reply.

Sorry if I was vague, i thought it might be overwhelming to post the whole code.

The math is trying to constrain mouseX and mouseY coordinates at the time that the new object is created to a a circular area of the screen. It draws a line from the origin to the mouse position and then finds the angle between that line and a line that goes directly through a 130 pt radius circle around the origin. the sin and cos functions inside the constraint show where the mouseX and mouseY position would fall along the edge of the circle. (Maybe there was a less complicated way of doing this?)

It seems that the problem is with the arguments feeding into the constructor and not with the math because I am using this exact same code somewhere else, except its inside a function, and it works.

Is there any reason the arguments wouldn't be feeding into the constraint correctly?

here is the code for that (moveX, moveY, and moveZ store the current point of origin which changes throughout the sketch):

void mousePressed() {
// A new Stamp object
if(!press){

Stamp s = new Stamp(mouseX, mouseY, moveX, moveY, moveZ);

// Append to array
stamps = (Stamp[]) append(stamps,s);

if (counter < images.length-1){
counter ++;
} else {
counter=0;
}
}
}

PhiLho

Re: problem with constraint inside a constructor

2 years ago

Perhaps the computation of hypotenuse is wrong, as you don't take in account the coordinate shift when using the mouse X/Y values.
Note: take a look at atan2(), it is useful to compute an angle from two points from the origin. Probably doing part of your calculi.

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