Complex gradient loop

Processing Coding Questions
31

Thanks! And do I receive this message? “NullPointerException” for this line

inputs.pixels[ i ] = (x << 16) | y;

PImage inputs;
PGraphics grad;
PShader gradShader;

int N = 9;
float strength = 1.;
boolean bShowPoints = true;
boolean bSaveFrame = false;

void setup() {
  size( 750, 1000, P3D );
  //fullScreen( P3D, SPAN );
  colorMode( HSB, 360,100,100 );
  grad = createGraphics( width, height, P3D );
  gradShader = new PShader( this, gradVert, gradFrag );
  initControlPoints();
  gradShader.set( "strength", strength );
  noLoop();
}

void initControlPoints() {
    float[][] pos = {
  { 525, 150 }, { 990, 500 }, { 550, 925 },
  { 275, 725 }, { 500, 125 }, { 250, 200 }
};
color[] cols = { 
  color( 179, 100, 100 ), color( 68, 100, 100 ), color( 303, 100, 100 ),
  color( 299, 100, 100 ), color( 276, 100, 100 ), color( 193, 100, 100 )
};

  for( int i=0; i<N; i++ ) {
    int x = (int)(65536 * pos[i][0] / grad.width);
    int y = (int)(65536 * pos[i][1] / grad.height);
    inputs.pixels[ i ] = (x << 16) | y;
    inputs.pixels[ i+N ] = cols[i];
  }
  //inputs = createImage( N, 2, ARGB );
  //inputs.loadPixels();
  //float[] hues = new float[N];
  // for( int i=0; i<N; i++ ) hues[i] = random(360);
  //hues = sort( hues );
  //for( int i=0; i<N; i++ ) {
  //float ang = TAU*i/N;
  // float r = random( 0.2, 0.5 );
    // int x = (int)((0.5 + r*cos(ang)) * 65536);
    // int y = (int)((0.5 + r*sin(ang)) * 65536);
    //color c = color( hues[i], 100, 100 );
    //inputs.pixels[ i ] = (x << 16) | y;
    //inputs.pixels[ i+N ] = c;
  //}
 //inputs.updatePixels();
 //gradShader.set( "inputs", inputs );
 //gradShader.set( "N", N );
}

void draw() {
  gradShader.set( "bShowPoints", bShowPoints );
  grad.beginDraw();
  grad.noStroke();
  grad.shader( gradShader );
  grad.rect( 0, 0, grad.width, grad.height );
  grad.resetShader();
  grad.endDraw();
  image( grad, 0, 0 );
  if( bShowPoints ) 
    text( str(N)+"    "+str(strength), 8, 16 );
  if( bSaveFrame ) {
    String fileName = getClass().getSimpleName() + "-" +
      nf(year(),4) + "-" + nf(month(),2) + "-" + nf(day(),2) + "-" +
      nf(hour(),2) + "-" + nf(minute(),2) + "-" + nf(second(),2) + ".TIFF";
    save( fileName );
    println( "saved " + fileName );
    bSaveFrame = false;
  }
}

void keyPressed() {
  if( keyCode == ENTER ) initControlPoints();
  else if( keyCode == DOWN ) { 
    strength /= 1.1;    
    gradShader.set( "strength", strength );
  }
  else if( keyCode == UP ) { 
    strength *= 1.1;    
    gradShader.set( "strength", strength );
  }
  else if( keyCode == LEFT ) { N = max(N-1, 1);  initControlPoints(); }
  else if( keyCode == RIGHT ) { N++;  initControlPoints(); }
  else if( key == ' ' ) bShowPoints = !bShowPoints;
  else if( key == '+' ) bSaveFrame = true;
  redraw();
}


String[] gradVert = {"""
#version 330
uniform mat4 transformMatrix;
in vec4 position;
void main() {
  gl_Position = transformMatrix * position;
}
"""};


String[] gradFrag = {"""
#version 330
precision highp float;
uniform vec2 resolution;
uniform sampler2D inputs;
uniform int N;
uniform bool bShowPoints;
uniform float strength;
out vec4 fragColor;

void main() {
  float aspect = resolution.x/resolution.y;
  vec2 uv = gl_FragCoord.xy / resolution.y;
  vec3 col = vec3(0.);
  float totw = 0.;
  for( int i=0; i<N; i++ ) {
    vec4 posData = texelFetch( inputs, ivec2( i, 0 ), 0 ) * 255.0;
    float x = (posData.a * 256 + posData.r)*aspect;
    float y = posData.g * 256 + posData.b;
    vec2 pos = vec2( x, y ) / 65536.0;
    vec3 c = texelFetch( inputs, ivec2( i, 1 ), 0 ).rgb;
    float d = length( uv - pos );
    float w = exp( -d*d*N*strength );
    if( w > 0 ) {
      col += c * w;
      totw += w;
    }
  }
  if( totw > 0. ) col /= totw;

  if( bShowPoints ) {
    for( int i=0; i<N; i++ ) {
      vec4 posData = texelFetch( inputs, ivec2( i, 0 ), 0 ) * 255.0;
      float x = (posData.a * 256 + posData.r)*aspect;
      float y = posData.g * 256 + posData.b;
      vec2 pos = vec2( x, y ) / 65536.0;
      vec3 c = texelFetch( inputs, ivec2( i, 1 ), 0 ).rgb;
      float d = length( uv - pos );
      if( d < 0.01 ) col = vec3(1.);
      if( d < 0.007 ) col = c;
    }
  }

  fragColor = vec4( col, 1. );
}
"""};