processing/java/examples/Topics/Simulate/Spring/Spring.pde at master · p-render/processing · GitHub

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/**

* Spring.

* Click, drag, and release the horizontal bar to start the spring.

// Spring drawing constants for top bar

int springHeight = 32; // Height

int left; // Left position

int right; // Right position

int max = 200; // Maximum Y value

int min = 100; // Minimum Y value

boolean over = false; // If mouse over

boolean move = false; // If mouse down and over

// Spring simulation constants

float M = 0.8; // Mass

float K = 0.2; // Spring constant

float D = 0.92; // Damping

float R = 150; // Rest position

// Spring simulation variables

float ps = R; // Position

float vs = 0.0; // Velocity

float as = 0; // Acceleration

float f = 0; // Force

void setup() {

size(640, 360);

rectMode(CORNERS);

noStroke();

left = width/2 - 100;

right = width/2 + 100;

}

void draw() {

background(102);

updateSpring();

drawSpring();

}

void drawSpring() {

// Draw base

fill(0.2);

float baseWidth = 0.5 * ps + -8;

rect(width/2 - baseWidth, ps + springHeight, width/2 + baseWidth, height);

// Set color and draw top bar

if(over || move) {

fill(255);

} else {

fill(204);

}

rect(left, ps, right, ps + springHeight);

}

void updateSpring() {

// Update the spring position

if(!move) {

f = -K * (ps - R); // f=-ky

as = f / M; // Set the acceleration, f=ma == a=f/m

vs = D * (vs + as); // Set the velocity

ps = ps + vs; // Updated position

}

if(abs(vs) < 0.1) {

vs = 0.0;

}

// Test if mouse is over the top bar

if(mouseX > left && mouseX < right && mouseY > ps && mouseY < ps + springHeight) {

over = true;

} else {

over = false;

}

// Set and constrain the position of top bar

if(move) {

ps = mouseY - springHeight/2;

ps = constrain(ps, min, max);

}

void mousePressed() {

if(over) {

move = true;

}

void mouseReleased() {

move = false;

}

processing/java/examples/Topics/Simulate/Spring/Spring.pde at master · p-render/processing · GitHub

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