Create blend_mode.rb

Author: monkstone

demo/blend_mode.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+require 'picrate'
+
+class BlendModeSketch < Processing::App
+  java_import 'com.jogamp.opengl.GL3'
+  java_import 'com.jogamp.opengl.GLContext'
+
+  attr_reader :gl
+  def setup
+    sketch_title 'Blend Mode Difference P2D'
+    noStroke
+    fill(255)
+    # DIFFERENCE is not supported in P2D / P3D
+    # blendMode(DIFFERENCE)
+    @gl = GLContext.getCurrentGL.getGL2
+  end
+
+  def draw
+    background(255)
+    # This provides blendMode(DIFFERENCE) in P2D / P3D
+    gl.glEnable(GL3::GL_BLEND)
+    gl.glBlendFunc(GL3::GL_ONE_MINUS_DST_COLOR, GL3::GL_ZERO)
+    20.times do |i|
+      sz = 50 + (i % 4) * 50
+      x = width * noise(i * 0.527 + millis * 0.0003)
+      y = height * noise(i * 0.729 + millis * 0.0001)
+      circle(x, y, sz)
+    end
+  end
+
+  def settings
+    size 600, 600, P3D
+    smooth 8
+  end
+end
+
+BlendModeSketch.new