electrostatics.vl

// Welcome to VectorLang!
// example: electrostatics

external Q1 = 1;
external Q1pos = {3.5, 3.5};
external Q2 = -1;
external Q2pos = {6.5, 6.5};
external gridWidth = 10;

const step = 0.5;

def fieldComponent(vector pos, number q, vector qPos) -> vector = [
    val diff := pos - qPos;

    if (pos != qPos) diff.normalized() * (q / diff.length().sqr())
    else {0, 0}
];

def field(vector pos) -> vector
    = fieldComponent(pos, Q1, Q1pos) + fieldComponent(pos, Q2, Q2pos);

def plotField(vector pos) -> void = if (pos.x <= gridWidth and pos.y <= gridWidth) [
    push();
    translate(pos);

    val pf := field(pos);

    if (pf.length() > step) [
        fill(WHITE.blend(RED, (pf.length() - step) / step));
        pf := pf.clampLength(0, step);
    ];

    plot(pf);
    pop();

    plotField(pos + (
        if (pos.x >= gridWidth) {-pos.x, step}
        else {step, 0}
    ));
];

def main() -> void = plotField({0, 0});