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‎docs/_posts/2019-03-01-Using-Vec3D.md‎

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---
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layout: post
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title: "Using Vec3D"
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date: 2019-03-01 10:60:08 +0000
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categories: vecmath update
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---
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# Example Usage
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```ruby
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GEM_HOME = '/home/tux/.gem/ruby/2.6.0'
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require 'vecmath'
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color_mode(RGB, 1)
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def draw
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background(0)
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@renderer ||= AppRender.new(graphics)
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# Move the origin so that the scene is centered on the screen.
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translate(width / 2, height / 2, 0.0)
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# Set up the lighting.
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setup_lights
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# Rotate the local coordinate system.
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smooth_rotation(5.0, 6.7, 7.3)
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# Draw the inner object.
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no_stroke
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fill(smooth_colour(10.0, 12.0, 7.0))
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draw_icosahedron(5, 60.0, false)
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# Rotate the local coordinate system again.
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smooth_rotation(4.5, 3.7, 7.3)
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# Draw the outer object.
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stroke(0.2)
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fill(smooth_colour(6.0, 9.2, 0.7))
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draw_icosahedron(5, 200.0, true)
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end
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def setup_lights
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ambient_light(0.025, 0.025, 0.025)
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directional_light(0.2, 0.2, 0.2, -1, -1, -1)
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spot_light(1.0, 1.0, 1.0, -200, 0, 300, 1, 0, -1, PI / 4, 20)
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end
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# Generate a vector whose components change smoothly over time in the range
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# (0..1). Each component uses a Math.sin function to map the current time in
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# milliseconds in the range (0..1).A 'speed' factor is specified for each
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# component.
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def smooth_vector(s1, s2, s3)
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mills = millis * 0.00003 ## Lazydogs factor
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# mills = millis * 0.0000001 ## worked for me a bit slower!!
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x = 0.5 * sin(mills * s1) + 0.5
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y = 0.5 * sin(mills * s2) + 0.5
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z = 0.5 * sin(mills * s3) + 0.5
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Vec3D.new(x, y, z)
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end
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# Generate a colour which smoothly changes over time.
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# The speed of each component is controlled by the parameters s1, s2 and s3.
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def smooth_colour(s1, s2, s3)
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v = smooth_vector(s1, s2, s3)
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color(v.x, v.y, v.z)
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end
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# Rotate the current coordinate system.
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# Uses smooth_vector to smoothly animate the rotation.
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def smooth_rotation(s1, s2, s3)
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r1 = smooth_vector(s1, s2, s3)
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rotate_x(2.0 * Math::PI * r1.x)
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rotate_y(2.0 * Math::PI * r1.y)
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rotate_x(2.0 * Math::PI * r1.z)
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end
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# Draw an icosahedron defined by a radius r and recursive depth d.
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# Geometry data will be saved into dst. If spherical is true then the
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# icosahedron is projected onto the sphere with radius r.
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def draw_icosahedron(depth, r, spherical)
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# Calculate the vertex data for an icosahedron inscribed by a sphere radius
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# 'r'. Use 4 Golden Ratio rectangles as the basis.
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gr = (1.0 + Math.sqrt(5.0)) / 2.0
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h = r / Math.sqrt(1.0 + gr * gr)
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v = [
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Vec3D.new(0, -h, h * gr),
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Vec3D.new(0, -h, -h * gr),
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Vec3D.new(0, h, -h * gr),
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Vec3D.new(0, h, h * gr),
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Vec3D.new(h, -h * gr, 0),
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Vec3D.new(h, h * gr, 0),
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Vec3D.new(-h, h * gr, 0),
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Vec3D.new(-h, -h * gr, 0),
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Vec3D.new(-h * gr, 0, h),
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Vec3D.new(-h * gr, 0, -h),
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Vec3D.new(h * gr, 0, -h),
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Vec3D.new(h * gr, 0, h)
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]
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# Draw the 20 triangular faces of the icosahedron.
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r = 0.0 unless spherical
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begin_shape(TRIANGLES)
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draw_triangle(depth, r, v[0], v[7], v[4])
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draw_triangle(depth, r, v[0], v[4], v[11])
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draw_triangle(depth, r, v[0], v[11], v[3])
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draw_triangle(depth, r, v[0], v[3], v[8])
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draw_triangle(depth, r, v[0], v[8], v[7])
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draw_triangle(depth, r, v[1], v[4], v[7])
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draw_triangle(depth, r, v[1], v[10], v[4])
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draw_triangle(depth, r, v[10], v[11], v[4])
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draw_triangle(depth, r, v[11], v[5], v[10])
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draw_triangle(depth, r, v[5], v[3], v[11])
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draw_triangle(depth, r, v[3], v[6], v[5])
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draw_triangle(depth, r, v[6], v[8], v[3])
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draw_triangle(depth, r, v[8], v[9], v[6])
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draw_triangle(depth, r, v[9], v[7], v[8])
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draw_triangle(depth, r, v[7], v[1], v[9])
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draw_triangle(depth, r, v[2], v[1], v[9])
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draw_triangle(depth, r, v[2], v[10], v[1])
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draw_triangle(depth, r, v[2], v[5], v[10])
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draw_triangle(depth, r, v[2], v[6], v[5])
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draw_triangle(depth, r, v[2], v[9], v[6])
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end_shape
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end
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##
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# Draw a triangle either immediately or subdivide it first.
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# If depth is 1 then draw the triangle otherwise subdivide first.
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#
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def draw_triangle(depth, r, p1, p2, p3)
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if depth == 1
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p1.to_vertex(@renderer)
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p2.to_vertex(@renderer)
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p3.to_vertex(@renderer)
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else
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# Calculate the mid points of this triangle.
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v1 = (p1 + p2) * 0.5
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v2 = (p2 + p3) * 0.5
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v3 = (p3 + p1) * 0.5
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unless r == 0.0
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# Project the vertices out onto the sphere with radius r.
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v1.normalize!
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v1 *= r
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v2.normalize!
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v2 *= r
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v3.normalize!
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v3 *= r
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end
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## Generate the next level of detail
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depth -= 1
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draw_triangle(depth, r, p1, v1, v3)
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draw_triangle(depth, r, v1, p2, v2)
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draw_triangle(depth, r, v2, p3, v3)
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# Uncomment out the next line to include the central part of the triangle.
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# draw_triangle(depth, r, v1, v2, v3)
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end
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end
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```

‎docs/_posts/2019-03-01-welcome-to-vecmath-gem.md‎

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date: 2019-03-01 09:58:08 +0000
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categories: vecmath update
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---
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# Background
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# Example Usage
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The vecmath Vec2D and Vec3D classes were originally build for JRubyArt and provide more ruby-like vector classes than the somewhat suspect vanilla processing PVector class (that doesn't know whether it's 2D or 3D). Further the AppRender class enables direct writing of vector to vertex
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```ruby
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# ===== Default : Default
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GEM_HOME = '/home/tux/.gem/ruby/2.6.0'
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require 'vecmath'
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require 'forwardable'
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# Building the Gem
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# Here we use the JRubyArt Vec2D class, and AppRender class (for vec.to_vertex)
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# Further we use the power of ruby (metaprogramming) to make Branch enumerable
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# and use Forwardable to define which enumerable methods we want to use.
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visor_class :Branch do
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include Enumerable
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extend Forwardable
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def_delegators(:@children, :<<, :each, :length)
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# variance angle for growth direction per time step
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THETA = Math::PI / 6
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# max segments per branch
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MAX_LEN = 100
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# max recursion limit
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MAX_GEN = 3
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# branch chance per time step
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BRANCH_CHANCE = 0.05
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# branch angle variance
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BRANCH_THETA = Math::PI / 3
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attr_reader :position, :dir, :path, :children, :xbound, :speed, :ybound, :app
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All you need is `mvn` to build the gem, and a ruby installation
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def initialize(pos, dir, speed)
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@renderer ||= AppRender.new(graphics)
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@position = pos
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@dir = dir
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@speed = speed
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@path = []
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@children = []
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@xbound = Boundary.new(0, width)
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@ybound = Boundary.new(0, height)
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path << pos
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end
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def run
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grow
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display
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end
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private
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# NB: use of both rotate! (changes original) rotate (returns a copy) of Vec2D
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def grow
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check_bounds(position + (dir * speed)) if path.length < MAX_LEN
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@position += (dir * speed)
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dir.rotate!(rand(-0.5..0.5) * THETA)
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path << position
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if (length < MAX_GEN) && (rand < BRANCH_CHANCE)
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branch_dir = dir.rotate(rand(-0.5..0.5) * BRANCH_THETA)
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self << Branch.new(position.copy, branch_dir, speed * 0.99)
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end
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each(&:grow)
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end
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def display
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begin_shape
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stroke(255)
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no_fill
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path.each { |vec| vec.to_vertex(@renderer) }
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end_shape
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each(&:display)
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end
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def check_bounds(pos)
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dir.x *= -1 if xbound.exclude? pos.x
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dir.y *= -1 if ybound.exclude? pos.y
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end
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end
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# we are looking for excluded values
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Boundary = Struct.new(:lower, :upper) do
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def exclude?(val)
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!(lower...upper).cover? val
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end
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end
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@root = Branch.new(
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Vec2D.new(0, height / 2),
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Vec2D.new(1, 0),
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10.0
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)
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def draw
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background(0)
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root.run
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end
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```
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1. clone Repo
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2. cd Repo
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3. rake

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