# Recursion - PShape

![](/files/-MWKyqUHB51ZzomQOd4N)

In the code below, we define a Recursive function: `recursivePattern()` that creates repeated versions of the PShape passed in as parameter s.

* **parameter: PShape s** - shape to be rendered
* **parameter: int count** - controls number of repeats - insures termination 
* **recursivePattern()** defines the repetition structure
* **shape( s, 0, 0)** : render the shape, is the task that is repeated
* createShape1( float w, float h, color c1) - used to create customPShape

```java
//simple PShape
//Rounded rectangle
PShape createShape1( float w, float h, color c1 ) {
  PShape s = createShape( RECT, 0, 0, w, h, 10);
  s.setFill( c1);
  return s;
}
```

## recursivePattern(PShape s, int count, color  c1 ) 

```java
//Parameters:  PShape shape to be rendered
// count - how many to create,  termination variable
// color - modified at each recursive call
void recursivePattern( PShape s, int count, color c1) {
  if (count <1 ) { //TERMINATION CONDITION
    return; //stop function execution by returning from the function
  }
  //CHANGE LOGIC to create variation in size, color, rotation...etc
  float scaleFactor = map( count, maxCount, 1, 1.0, 0.5); 
  s.scale(scaleFactor, scaleFactor ); // change
  color curColor = color ( hue( c1), saturation( c1), brightness( c1) * 0.8, 50);
  s.setFill( curColor);
  
  //TASK: 
  shape( s, 0, 0); //draw the shape on the canvas at x=0,y=0.
  s.resetMatrix(); //undo shape scaling
  
  //RECURSIVE CALL - modify parameter value
  recursivePattern( s,  count-1, curColor ); //recursive call - changed values for count, color
}
```

## Program using recursivePattern function

```java

int maxCount = 5;
color c1 ;

void setup() {
  size( 600, 600); //use size(600,600,P2D) if possible
  colorMode( HSB, 360, 100, 100, 100);
  c1 = color ( 200, 100, 100);
}

void draw() {
  if (mousePressed) {
    translate(mouseX, mouseY);
    PShape s = createShape1(100, 100, c1 );
    recursivePattern( s, maxCount, c1); //here level is initialized at 5 because we decrement it inside the recursive function
    resetMatrix();
  }
}
```

## HSB Colormode - Set Fill at the Vertex Level - Shader Option

Once a design has been developed using grayscale color values as show above, then it's very easy using HSB colormode to add hueValues. Processing using P2D mode as specified in the size( 600,600, P2D) supports vertex shaders, where gradient colors are computed for fill( ) values specified between vertex for PShape objects.

![](/files/-M0-KduyfDM1uL-7Eyao)

```java
        //size(600,600, P2D); //vertex shading using P2D
        //colorMode(HSB, 360,100,100);
        //float len = 100;

        //reducing brightness value between vertex points
        PShape vertexShape(float len, color c1){
            PShape s = createShape();
            s.beginShape();
            s.fill(c1); // 
            s.vertex( 0, 0 ); //point origin
            s.fill(hue(c1), saturation(c1), brightness(c1)*0.8 ); // reduce brightness
            s.vertex( len *.4, 0 ); //point(40,0)
            s.fill(hue(c1), saturation(c1), brightness(c1)*0.6 ); // reduce brightness
            s.vertex( len *.6, len*.6 ); //point(60,60);
            s.fill(hue(c1), saturation(c1), brightness(c1)*0.4 ); // reduce brightness
            s.vertex( 0, len *.4 ); //point(0,40);
            s.fill(hue(c1), saturation(c1), brightness(c1)*0.2 ); // reduce brightness
            s.vertex( 0, 0 );
            s.endShape(CLOSE); //end shape
            return s;
        }
```

## Vertex Shading Example

![](/files/-M0-Kdv-rLWVnVsCh5wu)

The image above uses fill variation between each vertex, as shown above, to create enhanced depth for the pattern.

If we use the processing P2D rendering context, we can set a different fill value and stroke value for each vertex, this allows us to create visual depth in the pattern. When incorporated into a simple recursive function this can create interesting complex images.\
P2D might not work on some computers, if not, then just use regular: size(600,600);. You will need to create an interesting pattern using fill outside of the beginShape() function that impacts the entire shape.

## Framecount as a timer - Option

We can use frameCount and modulus, to add a timer to the draw loop and (we can also rotate the pattern each time it is drawn using a similar technique)

```java
if(framecount % 10 == 0){
//this event occurs every 10 frames
//doSomething every 10 frames
}
```


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