Color Gradients 1-4

clrGrad_1_4.pde

color blue = 0xff0000ff;
color magenta = 0xffff00ff; 
color red = 0xffff0000;
color yellow = 0xffffff00;
color startc;
color stopc;

float margin = 32;
float left = margin;
float right;
float top = margin;
float bottom;
float horizchange;
float step = 1;
float clrstep; 
float horizfreq = 0.033;
float clrfreq = 0.05;

void setup() {
  size(512, 256);
  right = width - margin;
  bottom = height - margin;
}

void draw() {
  step = map(mouseY, 0, height, 1, 7);
  clrstep = cos(frameCount * clrfreq) * 0.5 + 0.5;
  startc = lerpColor(red, yellow, clrstep);
  stopc = lerpColor(blue, magenta, clrstep);

  background(0xffffffff);

  for (float i = top, fcnti; i <= bottom; i += step) {
    fcnti = frameCount + i;
    horizchange = cos(fcnti * horizfreq) * margin;
    stroke(lerpColor(startc, stopc, (i - top) / (bottom - top)));
    line(left + horizchange, i, 
      right + horizchange, i);
  }
}