manyfold3d/mittsu-mesh_analysis

$LOAD_PATH.unshift File.expand_path("../lib", __dir__)

require "mittsu"
require "mittsu/mesh_analysis"
require "mittsu/opengl"

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
ASPECT = SCREEN_WIDTH.to_f / SCREEN_HEIGHT.to_f

scene = Mittsu::Scene.new
camera = Mittsu::PerspectiveCamera.new(75.0, ASPECT, 0.1, 1000.0)

renderer = Mittsu::OpenGL::Renderer.new width: SCREEN_WIDTH, height: SCREEN_HEIGHT, title: "Collapsing edges with a winged edge meshes"

geometry = Mittsu::TorusKnotGeometry.new(2, 0.8, 64, 16)

# Render as wireframe AND as a shaded surface so that we can still see holes
material = Mittsu::MeshBasicMaterial.new(color: 0xffff00, wireframe: true)
wireframe = Mittsu::Mesh.new(geometry, material)
scene.add(wireframe)
material = Mittsu::MeshLambertMaterial.new(color: 0x800080)
surface = Mittsu::Mesh.new(geometry, material)
scene.add(surface)

light = Mittsu::DirectionalLight.new(0xffffff, 1)
light.position.set(0.9, 0.9, 1)
light_object = Mittsu::Object3D.new
light_object.add(light)
scene.add(light_object)

ambient = Mittsu::AmbientLight.new(0x3f3f3f)
ambient_object = Mittsu::Object3D.new
ambient_object.add(ambient)
scene.add(ambient_object)

camera_container = Mittsu::Object3D.new
camera_container.add(camera)
camera.position.z = 5.0
scene.add(camera_container)

renderer.window.on_resize do |width, height|
  renderer.set_size(width, height)
  camera.aspect = width.to_f / height.to_f
  camera.update_projection_matrix
end

X_AXIS = Mittsu::Vector3.new(1.0, 0.0, 0.0)
Y_AXIS = Mittsu::Vector3.new(0.0, 1.0, 0.0)
mouse_delta = Mittsu::Vector2.new
last_mouse_position = Mittsu::Vector2.new

renderer.window.on_mouse_button_pressed do |button, position|
  if button == GLFW::MOUSE_BUTTON_LEFT
    last_mouse_position.copy(position)
  end
end

renderer.window.on_mouse_move do |position|
  if renderer.window.mouse_button_down?(GLFW::MOUSE_BUTTON_LEFT)
    mouse_delta.copy(last_mouse_position).sub(position)
    last_mouse_position.copy(position)
    camera_container.rotate_on_axis(Y_AXIS, mouse_delta.x * 0.01)
    camera_container.rotate_on_axis(X_AXIS, mouse_delta.y * 0.01)
  end
end

decimator = Mittsu::MeshAnalysis::Decimator.new(geometry)
target = geometry.faces.count

renderer.window.run do
  # Decimate by 0.5% per frame
  target = (target * 0.995).floor
  exit if target < 50
  new_geometry, vertex_splits = decimator.decimate(target, vertex_splits: true)
  puts "f: #{new_geometry.faces.count}, v: #{new_geometry.vertices.count}"
  vertex_splits.each do |v|
    puts " - vsplit: #{v.vertex}, l: #{v.left}, r: #{v.right}, d: #{v.displacement.elements.inspect}"
  end

  # Forcibly replace the geometry.
  # There might be a better way to do
  # this that just rebuilds the render buffers
  wireframe.geometry = new_geometry.clone
  surface.geometry = new_geometry.clone

  renderer.render(scene, camera)
end