sin

→ sin()

Returns the sine of an angle — a number that swings between -1 and 1.

sin(sekhutlo)

As an angle grows, sin runs from 0 up to 1, back to 0, down to -1, back to 0 — and repeats without end. It is a wave.

This is what makes art in Bopa: give sin a growing angle and you get waves, rings and loops, without reaching for translate or rotate at all.

A circle with sin and cos. Every point on a circle can be worked out like this:

x = middle + cos(angle) * radius y = middle + sin(angle) * radius

By default the angle is read in radians, so a full turn is PEDI_PI. To work in degrees, call seeloSaSekhutlo(DEGREES) first.

The name is left as it stands. “Sine” is the word a Botswana learner writes on a BGCSE examination paper, in English — the sine, cosine and tangent ratios topic appears in the BGCSE syllabus in English only, and no Setswana word stands in its place.

Parameters

Name	Type	Description
`sekhutlo`	`palo`	The angle, in radians by default, or in degrees when `seeloSaSekhutlo(DEGREES)` is set.

Examples

A wave drawn out of points

Open in editor ↗

tiro setaLoeto() {
  thalaKanefase(400, 400);
  bokamorago(18, 22, 34);
  tlogelaMothalo();

  gopheta (diri x = 0; x < 400; x = x + 4) {
    // sin e busa -1..1, e lekanyediwa mo bogodimong jwa kanefase
    metlha lekhubu = sin(x * 0.03);
    metlha y = 200 + lekhubu * 120;

    tlatsaMmala(lekanyetsa(lekhubu, -1, 1, 60, 250), 150, 220);
    thalaSediko(x, y, 10);
  }
}

Three waves, stacked

Open in editor ↗

tiro setaLoeto() {
  thalaKanefase(400, 400);
  bokamorago(245);
  boketeMothalo(2);

  metlha bogolo = [40, 70, 100];
  metlha lebelo = [0.08, 0.04, 0.02];

  gopheta (diri m = 0; m < 3; m = m + 1) {
    mothaloMmala(60 + m * 70, 130 + m * 30, 220 - m * 50);

    gopheta (diri x = 0; x < 400; x = x + 2) {
      metlha y = 110 + m * 90 + sin(x * lebelo[m]) * bogolo[m];
      thalaNtlha(x, y);
    }
  }
}

sin

Parameters

Examples

See also