Voronoi Shadertoy Sketch JRubyArt

load_library :PixelFlow
java_import 'java.nio.ByteBuffer'
java_import 'com.jogamp.opengl.GL2'
java_import 'com.thomasdiewald.pixelflow.java.DwPixelFlow'
java_import 'com.thomasdiewald.pixelflow.java.dwgl.DwGLTexture'
java_import 'com.thomasdiewald.pixelflow.java.imageprocessing.DwShadertoy'
# PixelFlow | Copyright (C) 2017 Thomas Diewald - www.thomasdiewald.com
# translated to JRubyArt and refactored by Martin Prout
# https://github.com/diwi/PixelFlow.git
#
# A Processing/Java library for high performance GPU-Computing. MIT
# License: https://opensource.org/licenses/MIT
#
# Shadertoy Demo:   https://www.shadertoy.com/view/ldl3W8
# Shadertoy Author: https://www.shadertoy.com/user/iq
TITLE = 'Shadertoy Voronoi Distances'.freeze
WH = 256
attr_reader :toy, :context

def settings
  size(1280, 720, P2D)
  smooth(0)
end

def setup
  sketch_title 'Warming Up'
  surface.set_resizable(true)
  @tex0 = DwGLTexture.new
  @context = DwPixelFlow.new(self)
  context.print
  context.printGL
  @toy = DwShadertoy.new(context, data_path('voronoi_distances.frag'))
  frame_rate(60)
  toy.set_iChannel(0, tex_noise)
end

def tex_noise
  texture = DwGLTexture.new
  (0...WH * WH * 4).step(4) do
    bdata << rand(-127..127) # NB: java bytes are signed
    bdata << rand(-127..127)
    bdata << rand(-127..127)
    bdata << -1
  end
  # puts Java::JavaLang::Byte::toUnsignedInt(bdata[3])
  texture.resize(
    context,
    GL2::GL_RGBA8,
    WH,
    WH,
    GL2::GL_RGBA,
    GL2::GL_BYTE,
    GL2::GL_LINEAR,
    GL2::GL_MIRRORED_REPEAT,
    4,
    1,
    Java::JavaNio::ByteBuffer.wrap(bdata.to_java(Java::byte))
  )
  texture
end

def draw
  toy.apply(g)
  title_format = '%s | size: [%d, %d] frame_count: %d fps: %6.2f'
  surface.set_title(
    format(title_format, TITLE, width, height, frame_count, frame_rate)
  )
end