icosahedra variants

Author: monkstone

processing_app/basics/form/icosahedron_shape.rb

@@ -0,0 +1,82 @@
+# This sketch uses magic numbers for icosahedron, see lib/icosahedron.rb for a calculated version
+# But neatly illustrates use of `tap` with PShape and `slice` with an array
+attr_reader :ico
+
+def setup
+  sketch_title('Icosahedron Shape')
+  @ico = create_icosahedron
+end
+
+def draw
+  background(0, 0, 200)
+  lights
+  translate(width / 2, height / 2)
+  scale(150)
+  push_matrix
+  rotate_x(0.01 * frame_count)
+  rotate_z(0.025 * frame_count)
+  shape(ico)
+  pop_matrix
+end
+
+FACES = [
+  2, 1, 0,
+  3, 2, 0,
+  4, 3, 0,
+  5, 4, 0,
+  1, 5, 0,
+
+  11, 6,  7,
+  11, 7,  8,
+  11, 8,  9,
+  11, 9,  10,
+  11, 10, 6,
+
+  1, 2, 6,
+  2, 3, 7,
+  3, 4, 8,
+  4, 5, 9,
+  5, 1, 10,
+
+  2,  7, 6,
+  3,  8, 7,
+  4,  9, 8,
+  5, 10, 9,
+  1, 6, 10
+].freeze
+
+VERTS = [
+  0.000,  0.000,  1.000,
+  0.894,  0.000,  0.447,
+  0.276,  0.851,  0.447,
+  -0.724,  0.526,  0.447,
+  -0.724, -0.526,  0.447,
+  0.276, -0.851,  0.447,
+  0.724,  0.526, -0.447,
+  -0.276,  0.851, -0.447,
+  -0.894,  0.000, -0.447,
+  -0.276, -0.851, -0.447,
+  0.724, -0.526, -0.447,
+  0.000,  0.000, -1.000
+].freeze
+
+def create_icosahedron
+  create_shape.tap do |sh|
+    sh.begin_shape(TRIANGLES)
+    sh.no_stroke
+    sh.fill(200, 0, 0)
+    FACES.each_slice(3).each do |a, b, c|
+      one = a * 3
+      two = b * 3
+      three = c * 3
+      sh.vertex(VERTS[one], VERTS[one + 1], VERTS[one + 2])
+      sh.vertex(VERTS[two], VERTS[two + 1], VERTS[two + 2])
+      sh.vertex(VERTS[three], VERTS[three + 1], VERTS[three + 2])
+    end
+    sh.end_shape
+  end
+end
+
+def settings
+  size(400, 400, P3D)
+end

processing_app/basics/form/lib/icosahedron.rb

@@ -1,53 +1,51 @@
+# Using fully qualified java names instead of 'java_import'
 class Icosahedron
-  attr_reader :app, :r 
-  TRIANGLES = Java::ProcessingCore::PConstants.TRIANGLES
+  attr_reader :app, :radius, :renderer
   def initialize(app, radius)
-    @app, @r = app, radius
+    @app = app
+    @radius = radius
+    @renderer = Java::MonkstoneVecmath::GfxRender.new(app.g)
   end
-  
-  ##
+
   # Draw an icosahedron defined by a radius r.
-  #
   def draw
     # Calculate the vertex data for an icosahedron inscribed by a sphere radius 'r'.
     # Use 4 Golden Ratio rectangles as the basis.
     phi = (1.0 + Math.sqrt(5.0)) / 2.0
-    h = r / Math.sqrt(1.0 + phi * phi)
+    h = radius / Math.sqrt(1.0 + phi * phi)
     v =
       [
-    Vec3D.new(0, -h, h * phi), Vec3D.new(0, -h, -h * phi), Vec3D.new(0, h, -h * phi), Vec3D.new(0, h, h * phi),
-    Vec3D.new(h, -h * phi, 0), Vec3D.new(h, h * phi, 0), Vec3D.new(-h, h * phi, 0), Vec3D.new(-h, -h * phi, 0),
-    Vec3D.new(-h * phi, 0, h), Vec3D.new(-h * phi, 0, -h), Vec3D.new(h * phi, 0, -h), Vec3D.new(h * phi, 0, h)
-    ]
-    
-    app.begin_shape(TRIANGLES)      
-      draw_triangle(v[0], v[7],v[4])
-      draw_triangle(v[0], v[4], v[11])
-      draw_triangle(v[0], v[11], v[3])
-      draw_triangle(v[0], v[3], v[8])
-      draw_triangle(v[0], v[8], v[7])      
-      draw_triangle(v[1], v[4], v[7])
-      draw_triangle(v[1], v[10], v[4])
-      draw_triangle(v[10], v[11], v[4])
-      draw_triangle(v[11], v[5], v[10])
-      draw_triangle(v[5], v[3], v[11])
-      draw_triangle(v[3], v[6], v[5])
-      draw_triangle(v[6], v[8], v[3])
-      draw_triangle(v[8], v[9], v[6])
-      draw_triangle(v[9], v[7], v[8])
-      draw_triangle(v[7], v[1], v[9])      
-      draw_triangle(v[2], v[1], v[9])
-      draw_triangle(v[2], v[10], v[1])
-      draw_triangle(v[2], v[5], v[10])
-      draw_triangle(v[2], v[6], v[5])
-      draw_triangle(v[2], v[9], v[6])      
+        Vec3D.new(0, -h, h * phi), Vec3D.new(0, -h, -h * phi), Vec3D.new(0, h, -h * phi), Vec3D.new(0, h, h * phi),
+        Vec3D.new(h, -h * phi, 0), Vec3D.new(h, h * phi, 0), Vec3D.new(-h, h * phi, 0), Vec3D.new(-h, -h * phi, 0),
+        Vec3D.new(-h * phi, 0, h), Vec3D.new(-h * phi, 0, -h), Vec3D.new(h * phi, 0, -h), Vec3D.new(h * phi, 0, h)
+      ]
+    app.begin_shape(Java::ProcessingCore::PConstants.TRIANGLES)
+    draw_triangle(v[0], v[7], v[4])
+    draw_triangle(v[0], v[4], v[11])
+    draw_triangle(v[0], v[11], v[3])
+    draw_triangle(v[0], v[3], v[8])
+    draw_triangle(v[0], v[8], v[7])
+    draw_triangle(v[1], v[4], v[7])
+    draw_triangle(v[1], v[10], v[4])
+    draw_triangle(v[10], v[11], v[4])
+    draw_triangle(v[11], v[5], v[10])
+    draw_triangle(v[5], v[3], v[11])
+    draw_triangle(v[3], v[6], v[5])
+    draw_triangle(v[6], v[8], v[3])
+    draw_triangle(v[8], v[9], v[6])
+    draw_triangle(v[9], v[7], v[8])
+    draw_triangle(v[7], v[1], v[9])
+    draw_triangle(v[2], v[1], v[9])
+    draw_triangle(v[2], v[10], v[1])
+    draw_triangle(v[2], v[5], v[10])
+    draw_triangle(v[2], v[6], v[5])
+    draw_triangle(v[2], v[9], v[6])
     app.end_shape
   end
-  
-  def draw_triangle(p1, p2, p3)    
-    app.vertex(p1.x, p1.y, p1.z)
-    app.vertex(p2.x, p2.y, p2.z)
-    app.vertex(p3.x, p3.y, p3.z)    
+
+  def draw_triangle(pt1, pt2, pt3)
+    pt1.to_vertex(renderer)
+    pt2.to_vertex(renderer)
+    pt3.to_vertex(renderer)
   end
-  
-end
+end