Reorganize; DFT; Use Transformation Matrices

collision.lua

@@ -0,0 +1,9 @@
+local function DetectCollision(
+  xi, yi, vx, vy, xf, yf,
+  GetRadius,
+  GetRadialDerivative)
+  
+
+end
+
+return DetectCollision

conf.lua

@@ -0,0 +1,14 @@
+function love.conf( t )
+  t.modules.joystick = false
+  t.modules.physics = false
+  t.modules.touch = false
+  t.modules.video = false
+  
+  t.window.title = "By Your Own Beat"
+  t.window.width = 600                
+  t.window.height = 600
+  t.window.resizable = true
+  t.window.minwidth = 200
+  t.window.minheight = 200
+
+end

main.lua

@@ -4,13 +4,14 @@ local step = step
 local sitelenpona
 local text
 local marble
+local wave
 
 local sounds = {
 
 
-
 }
 
+
 local state 
 state = {
 
@@ -52,14 +53,29 @@ state = {
   },
 }
 
+local function UpdateWindowTransform( w, h )
+  local d = math.min( w, h )
+  local r = love.graphics.get
+  local tf = love.math.newTransform()
+
+  local size = 3
+
+  tf:translate( w / 2, h / 2)
+  tf:scale( d / size, -d / size )
+  transform = tf
+end
+
 function love.load()
+  UpdateWindowTransform( love.graphics.getDimensions() )
+
   love.graphics.setBackgroundColor( 245 / 255, 169 / 255, 184 / 255 ) --Trans pink.
   --love.graphics.setBackgroundColor( 91 / 255, 206 / 255, 250 / 255 ) --Trans blue.
-  sounds.goodPing = love.audio.newSource("soundTest.ogg", "static")
-  sounds.badPing = love.audio.newSource("chime8.ogg", "static")
+  sounds.goodPing = love.audio.newSource("sounds/soundTest.ogg", "static")
+  sounds.badPing = love.audio.newSource("sounds/chime8.ogg", "static")
   sitelenpona = assert( require "sitelenpona" )
   text = assert( require "text" )
   marble = assert( require "marble" )
+  wave = assert( require "wave" )
   return state.Reset()
 
 end
@@ -134,7 +150,6 @@ end
 
 
 function love.draw()
-  local w, h = love.graphics.getDimensions()
 
 
   love.graphics.setColor(1.0, 1.0, 1.0)
@@ -143,12 +158,18 @@ function love.draw()
   love.graphics.print( state.beatScoreThreshold, 0, 20)
   love.graphics.print( state.lastBeatScore, 0, 30 )
 
-  love.graphics.setColor(  91 / 255, 206 / 255, 250 / 255 )
-  love.graphics.circle("fill", w / 2, h / 2, 200)
 
-  sitelenpona.Draw( text.tok[state.currentBeat] )
+
+  love.graphics.push( "transform" )
+  love.graphics.applyTransform( transform )
+  wave.Draw()
+  love.graphics.pop()
+
+   sitelenpona.Draw( text.tok[state.currentBeat] )
+
   marble.Draw()
 
+
 end
 
 
@@ -157,8 +178,10 @@ function love.update( dt )
   dt = dt + state.timeToSimulate
   while dt > step do
     marble.Update()
+    wave.Update()
     dt = dt - step
   end
+  state.timeToSimulate = dt
 end
 
 function love.keypressed( key, code, isRepeat )
@@ -170,3 +193,8 @@ end
 function love.keyreleased( key, code )
   return marble.OnKey()
 end
+
+function love.resize( w, h )
+  UpdateWindowTransform( w, h )
+  if marble then marble.Resize() end
+end

marble.lua

@@ -1,11 +1,12 @@
 --Character controller. Renders point particle.
 local love = love
+--local wave = assert( require "wave" )
 local oldBuffer = love.graphics.newCanvas()
 local newBuffer = love.graphics.newCanvas()
 local step = assert( step )
 local state 
-local FRICTION = 0.008
-local MAXSPEED = 1.0
+local FRICTION = 0.01
+local MAXSPEED = 5.0
 
 local t, x, y, dx, dy, ddx, ddy
 
@@ -16,11 +17,14 @@ local function Update()
   dy = (1.0 - FRICTION) * dy + FRICTION * ddy
   local xf = x + dx * step * MAXSPEED
   local yf = y + dy * step * MAXSPEED
+  
+  x = xf
+  y = yf
 end
 
 local function OnKey()
   ddx = (love.keyboard.isScancodeDown( "d" ) and 1.0 or 0.0) - (love.keyboard.isScancodeDown( "a" ) and 1.0 or 0.0)
-  ddy = (love.keyboard.isScancodeDown( "s" ) and 1.0 or 0.0) - (love.keyboard.isScancodeDown( "w" ) and 1.0 or 0.0)
+  ddy = (love.keyboard.isScancodeDown( "w" ) and 1.0 or 0.0) - (love.keyboard.isScancodeDown( "s" ) and 1.0 or 0.0)
   
   local n = math.sqrt( ddx * ddx + ddy * ddy )
   if n < 0.001 then return end
@@ -32,18 +36,22 @@ local function Draw()
   local xf, yf = x + dt * dx, y + dt * dy
   
   local w, h = love.graphics.getDimensions()
-  local xi, yi = 1000.0 * x + 0.5 * w, 1000.0 * y + 0.5 * h
-  xf, yf = 1000.0 * xf + 0.5 * w, 1000.0 * yf + 0.5 * h
+  local xi, yi = transform:transformPoint( x, y )
+  xf, yf = transform:transformPoint( xf, yf )
+  
+  love.graphics.setColor( 0, 0, 0, 1 )
+  love.graphics.print( x, 0, 60 )
+  love.graphics.print( y, 0, 80 )
   
 
   love.graphics.setCanvas( newBuffer )
-  love.graphics.setColor(  1.0, 1.0, 1.0 , 0.9 ) --Trans blue.
+  love.graphics.setColor(  1.0, 1.0, 1.0 , 0.99 ) -- White.
   love.graphics.draw( oldBuffer ) --Time-dependent fade: overlay canvas over itself.
   
   --Render latest segment in trail.
-  love.graphics.setColor( 1.0, 1.0, 1.0, 1.0 ) --White?
+  love.graphics.setColor( 245 / 255, 169 / 255, 184 / 255, 1.0 ) --Trans pink.
   love.graphics.circle( "fill", xf, yf, 4.0 ) --TODO: replace with segments.
-  love.graphics.line( xi, yi, xf, yf )
+  --love.graphics.line( xi, yi, xf, yf )
   
   love.graphics.setCanvas( oldBuffer )
   love.graphics.clear( 1.0, 1.0, 1.0, 0.0 )
@@ -51,8 +59,9 @@ local function Draw()
   --Render circle directly to screen.
   love.graphics.setCanvas()
   love.graphics.draw( newBuffer )
-  love.graphics.setColor( 245 / 255, 169 / 255, 184 / 255 ) --Trans pink.
   love.graphics.circle( "fill", xf, yf, 5.0 )
+  love.graphics.setColor( 1, 1, 1, 1.0 ) --White.
+  love.graphics.circle( "line", xf, yf, 5.0 )
   
   oldBuffer, newBuffer = newBuffer, oldBuffer
 
@@ -64,6 +73,10 @@ end
 
 --Window resize.
 local function Resize()
+  newBuffer = love.graphics.newCanvas()
+  --TODO: render oldBuffer to new newBuffer, but scaled down.
+  oldBuffer = love.graphics.newCanvas()
+  
 
 end
 
@@ -87,4 +100,5 @@ return {
   Draw = Draw,
   Impact = Impact,
   Reset = Reset,
+  Resize = Resize,
 }

sitelenpona.lua

@@ -10,7 +10,7 @@ end
 sp.Draw = function( str )
   local w, h = love.graphics.getDimensions()
   local x, y = 0.5 * w - 128, 0.5 * h - 128
-  love.graphics.setColor( 1.0, 1.0, 1.0, 0.5 )
+  love.graphics.setColor( 1.0, 1.0, 1.0, 1.0 )
   love.graphics.draw( sp[str] or sp.q, x, y )
 end
 

wave.lua

@@ -0,0 +1,190 @@
+--Render and simulate 1D wave equation.
+local love = love
+local step = assert( step )
+
+local N = 25
+
+--Calculate discrete fourier transform of radius function.
+local DFT
+do
+  local twiddlec = {}
+  local twiddles = {}
+  for i = 1, N do
+    twiddlec[i], twiddles[i] = math.cos( - 2.0 * ( i - 1 ) * math.pi / N ), math.sin( - 2.0 * (i - 1) * math.pi / N )
+  end
+
+  local function Twiddle( j )
+    j = 1 + j % N
+    return twiddlec[j], twiddles[j]
+  end
+
+  --Slow Discrete Fourier Transform of a real sequence.
+  DFT = function( wave )
+    local seq = wave.radii
+    local dre, dim = wave.dftre, wave.dftim
+    for k = 0, N - 1 do
+
+      local x, y = 0, 0 --Fourier coefficients in bin k.
+
+      for n = 0, N - 1 do
+        local cos, sin = Twiddle( n * k )
+        x = x + seq[n + 1] * cos
+        y = y + seq[n + 1] * sin
+      end
+
+      dre[k + 1], dim[k + 1] = x / N , y / N
+    end
+  end
+
+end
+
+--Minimal-oscillation interpolant of a real function from its discrete Fourier coefficients.
+local Interpolate = function( wave, x )
+  local re, im = wave.dftre, wave.dftim
+  local y = re[1]
+
+  for k = 1, N / 2 do
+    local c, s = math.cos( x * k ), math.sin( x * k )
+    y = y
+    + c * re[k + 1]
+    - s * im[k + 1]
+    + c * re[N - k + 1]
+    + s * im[N - k + 1]
+
+  end
+
+  return y
+end
+
+--Derivative of the interpolation.
+local Derivative = function( wave, x )
+  local re, im = wave.dftre, wave.dftim
+
+  for k = 1, N / 2 do
+    local c, s = k * math.cos( x * k ), k * math.sin( x * k )
+    y = y
+    - c * im[k + 1]
+    - s * re[k + 1]
+    + c * im[N - k + 1]
+    - s * re[N - k + 1]
+
+  end
+
+  return y
+end
+
+--Second derivative of the interpolation.
+local SecondDerivative = function( wave, x )
+  local re, im = wave.dftre, wave.dftim
+
+  for k = 1, N / 2 do
+    local c, s = k * k * math.cos( x * k ), k * k * math.sin( x * k )
+    y = y
+    - c * re[k + 1]
+    + s * im[k + 1]
+    - c * re[N - k + 1]
+    - s * im[N - k + 1]
+
+  end
+
+  return y
+end
+
+local mt = { __index = {
+    DFT = DFT,
+    Interpolate = Interpolate,
+    Derivative = Derivative,
+    SecondDerivative = SecondDerivative } }
+
+local function Wave( )
+  local t = {
+    --radii[k] = radius of point on curve at angle (k - 1) / 13
+    radii = {},
+    --TIME derivative of radius
+    vrad = {},
+
+    --SPACE DFT of radius function (which is periodic)
+    dftre = {},
+    dftim = {},
+  }
+
+  for i = 1, N do
+    t.radii[i] = 1.0
+    t.vrad[i] = 0.0
+  end
+  DFT( t )
+
+  return setmetatable(t, mt)
+end
+
+
+local old = Wave() --State at beginning of tick.
+local cur = Wave() --State at end of tick.
+
+
+local function Draw()
+
+  -- Blue circle.
+  love.graphics.setColor(  91 / 255, 206 / 255, 250 / 255 )
+  love.graphics.circle("fill", 0, 0, 1)
+  local t = love.timer.getTime()
+
+  -- Debug dots.
+  for i = 1, N do
+
+    local th = ( i - 1 ) * 2.0 * math.pi / N
+    local cx, cy = cur.radii[i] * math.cos( th ), cur.radii[i] * math.sin( th )
+    love.graphics.setCanvas()
+    love.graphics.setColor( 0, 0, 0, 0.5 )
+    love.graphics.circle( "fill", cx, cy, 0.02 )
+
+    love.graphics.setColor( 1.0, 0, 0, 0.5 )
+    for k = 0.1, 1.0, 0.1 do
+      th = ( i - 1 + k ) * 2.0 * math.pi / N
+      r = cur:Interpolate( th )
+      x, y = r * math.cos( th ), r * math.sin( th )
+      love.graphics.circle( "fill", x, y, 0.01 )
+    end
+  end
+
+  love.graphics.setColor( 1, 1, 1, 0.5 )
+  local r = cur:Interpolate( t )
+  local x, y = r * math.cos( t ), r * math.sin( t )
+  love.graphics.circle( "fill", x, y, 0.02 )
+end
+
+local function Update()
+  --Deep copy of current state to old state.
+  for name, t in pairs( cur ) do
+    for i = 1, 13 do
+      old[name][i] = t[i]
+    end
+  end
+
+  local t = love.timer.getTime()
+  for i = 1, N do
+    cur.radii[i] = cur.radii[i] + old.vrad[i] * step
+    cur.vrad[i] = cur.vrad[i] - cur:SecondDerivative( ( i - 1 ) / N )
+  end
+
+  cur:DFT( )
+
+end
+
+local function DetectCollision( px, py, vpx, vpy )
+  local xi, xf = px + vpx * step, py + vpy * step
+end
+
+local function Reset()
+  old = Wave()
+  cur = Wave()
+end
+
+Reset()
+
+return {
+  Reset = Reset,
+  Update = Update,
+  DetectCollision = DetectCollision,
+  Draw = Draw,
+}