Color Gradients 2-10

clrGrad_2_10.pde

size(600, 200);
rectMode(CORNERS);
ellipseMode(RADIUS);
noStroke();

int[] blendModes = { BLEND, ADD, SUBTRACT }; 

// Red, Green, Blue, Cyan, Magenta, Yellow
color[] palette = { 0x55ff0000, 0x5500ff00, 
  0x550000ff, 0x5500ffff, 0x55ff00ff, 
  0x55ffff00 };

float rectWidth = width * 0.334; 
float centerX;
float centerY = height * 0.5;
float angle;
float radius = min(width, height) * 0.2675; 
float dist = rectWidth * 0.5 - radius;

// Blend background
fill(0xffd6d6d6); 
rect(0, 0, rectWidth, height);

// Add background.
fill(0xff000000); 
rect(rectWidth, 0, rectWidth * 2, height);

// Subtract background.
fill(0xffffffff); 
rect(rectWidth * 2, 0, width, height);

// Three modes, six overlapping circles.
for (int i = 0; i < 3; ++i) {
  centerX = rectWidth * 0.5 + width * i * 0.334;
  blendMode(blendModes[i]);
  for (int j = 0; j < 6; ++j) {
    angle = j * 0.1667 * TWO_PI;
    fill(palette[j]);
    ellipse(centerX + cos(angle) * dist, 
      centerY + sin(angle) * dist, 
      radius, radius);
  }
}