/* built with Studio Sketchpad: 
 *   https://sketchpad.cc
 * 
 * observe the evolution of this sketch: 
 *   https://playgramming.sketchpad.cc/sp/pad/view/ro.kD5Z$vPuAWW/rev.290
 * 
 * authors: 
 *   Devon Scott-Tunkin

 * license (unless otherwise specified): 
 *   creative commons attribution-share alike 3.0 license.
 *   https://creativecommons.org/licenses/by-sa/3.0/ 
 */ 



color red = color(255, 0, 0);
color black = color(0, 0, 255);

int Y_AXIS = 1;
int X_AXIS = 2;


void setup() {  // this is run once.   
    size(300, 300); 



} 

void draw() {  // this is run repeatedly.  
    for (int x = 0; x < width; x = x + 1) {
        strokeWeight(1);
        float percent = x / width;
        stroke(lerpColor(red, black, percent));
        line(0, x, width, x);
        
        setGradient(x, x, 100, 100, black, red, X_AXIS);
    }
}

void setGradient(int x, int y, float w, float h, color c1, color c2, int axis ) {

  noFill();

  if (axis == Y_AXIS) {  // Top to bottom gradient
    for (int i = y; i <= y+h; i++) {
      float inter = map(i, y, y+h, 0, 1);
      color c = lerpColor(c1, c2, inter);
      stroke(c);
      line(x, i, x+w, i);
    }
  }  
  else if (axis == X_AXIS) {  // Left to right gradient
    for (int i = x; i <= x+w; i++) {
      float inter = map(i, x, x+w, 0, 1);
      color c = lerpColor(c1, c2, inter);
      stroke(c);
      line(i, y, i, y+h);
    }
  }
}