commit d853f9f14c179c5dbf3485ae56397ff249a3a699
Author: Walter Oggioni <walter.oggioni@gmail.com>
Date:   Thu Jan 3 17:39:40 2019 +0100

    initial commit

diff --git a/geo2d.nim b/geo2d.nim
new file mode 100644
index 0000000..43c8a46
--- /dev/null
+++ b/geo2d.nim
@@ -0,0 +1,50 @@
+import mmath/smatrix
+import mmath/svector
+from nwo/utils import `...`
+from math import sin, cos
+
+type
+    X2d* = SquareSMatrix[3, float32]
+    P2d* = SVector[3, float32]
+    Rect2d* = object
+        tl*, br* : P2d
+
+proc newP2d*(x, y : float32) : P2d =
+    P2d(buildSVector[3, float32](x,y,1f32))
+
+proc x*(p : P2d) : float32 = p[0]
+proc y*(p : P2d) : float32 = p[1]
+
+proc newRect2d*(x, y, width, height : float32) : Rect2d = Rect2d(tl: newP2d(x,y), br: newP2d(x + width, y + height))
+proc top*(rect : Rect2d) : float32 = rect.tl.y
+proc bottom*(rect : Rect2d) : float32 = rect.br.y
+proc left*(rect : Rect2d) : float32 = rect.tl.x
+proc right*(rect : Rect2d) : float32 = rect.br.x
+proc width*(rect : Rect2d) : float32 = rect.br.x - rect.tl.x
+proc height*(rect : Rect2d) : float32 = rect.br.y - rect.tl.y
+proc `*`*(rect : Rect2d, xform : X2d) : Rect2d = Rect2d(tl: rect.tl * xform, br: rect.br * xform) 
+
+proc rot*(alpha: float32) : X2d = 
+    result = identity[3,float32]()
+    let ca = cos(alpha)
+    let sa = sin(alpha)
+    result[0,0] = ca
+    result[1,1] = ca
+    result[0,1] = sa
+    result[1,0] = -sa
+
+proc scale*(x, y: float32) : X2d = 
+    result = identity[3,float32]()
+    result[0,0] = x
+    result[1,1] = y  
+
+proc xlate*(x, y: float32) : X2d =
+    result = identity[3,float32]()
+    result[2,0] = x
+    result[2,1] = y
+
+proc scale*(center : P2d, x, y : float32) : X2d = xlate(-center.x, -center.y) * scale(x,y) * xlate(center.x, center.y)
+proc rot*(center : P2d, angle : float32) : X2d = xlate(-center.x, -center.y) * rot(angle) * xlate(center.x, center.y)
+
+    
+
diff --git a/grid.nim b/grid.nim
new file mode 100644
index 0000000..038beb7
--- /dev/null
+++ b/grid.nim
@@ -0,0 +1,73 @@
+import random
+from times import epochTime
+type Grid* = object 
+    rows*, columns* : uint32
+    data : seq[uint32]
+
+proc newGrid*(rows, columns : uint32) : Grid =
+    Grid(
+        rows: rows, 
+        columns: columns,
+        data: newSeq[uint32]((rows * columns + 8 - 1) div 8)
+    )
+
+proc get(grid : Grid, x, y : uint32) : bool =
+    assert x < grid.columns
+    assert y < grid.rows
+    let index = y * grid.columns + x
+    (grid.data[index div 8] and (1u32 shl (index mod 8))) != 0
+
+proc set(grid : var Grid, x, y : uint32, value : bool) : void =
+    assert x < grid.columns
+    assert y < grid.rows
+    let index = y * grid.columns + x
+    grid.data[(index div 8)] = 
+        if value:
+            grid.data[(index div 8)] or (1u32 shl (index mod 8))
+        else:
+            grid.data[(index div 8)] and (not (1u32 shl (index mod 8)))
+    
+template `[]`*(grid : Grid, x,y : uint32) : bool =
+    get(grid, x, y)
+
+template `[]=`*(grid : Grid, x,y : uint32, value : bool) =
+    set(grid, x, y, value)
+
+proc next_step*(old_grid, new_grid : var Grid) =
+    for x in 0..<old_grid.columns:
+        for y in 0..<old_grid.rows:
+            var alive_neighbours = 0 
+            if old_grid[(x+1) mod old_grid.columns, y]:
+                alive_neighbours += 1
+            if old_grid[(x+1) mod old_grid.columns, (y+1) mod old_grid.rows]:
+                alive_neighbours += 1
+            if old_grid[(x+1) mod old_grid.columns, (y-1) mod old_grid.rows]:
+                alive_neighbours += 1
+            if old_grid[(x-1) mod old_grid.columns, y]:
+                alive_neighbours += 1
+            if old_grid[(x-1) mod old_grid.columns, (y + 1) mod old_grid.rows]:
+                alive_neighbours += 1
+            if old_grid[(x-1) mod old_grid.columns, (y - 1) mod old_grid.rows]:
+                alive_neighbours += 1
+            if old_grid[x mod old_grid.columns, (y + 1) mod old_grid.rows]:
+                alive_neighbours += 1
+            if old_grid[x mod old_grid.columns, (y - 1) mod old_grid.rows]:
+                alive_neighbours += 1
+            
+            if old_grid[x, y]:
+                if alive_neighbours < 2 or alive_neighbours > 3:
+                    new_grid[x, y] = false
+                else:
+                    new_grid[x, y] = true
+            elif alive_neighbours == 3:
+                new_grid[x, y] = true
+            else:
+                new_grid[x, y] = false
+
+proc rand_init*(grid : var Grid) =
+    var rand = initRand(epochTime().int64)
+    for x in 0..<grid.columns:
+        for y in 0..<grid.rows:
+            grid[x, y] = (rand.next() mod 2) != 0
+
+
diff --git a/main.nim b/main.nim
new file mode 100644
index 0000000..476c148
--- /dev/null
+++ b/main.nim
@@ -0,0 +1,132 @@
+include options
+import sdl2, sdl2/gfx
+import grid
+import geo2d
+import mmath/smatrix
+import mmath/svector
+from nwo/utils import box
+
+discard sdl2.init(INIT_EVERYTHING)
+
+proc drawLine(renderer : RendererPtr, p0, p1 : P2d) = renderer.drawLine(p0.x.cint, p0.y.cint, p1.x.cint, p1.y.cint)
+proc fillRect(renderer : RendererPtr, rect : Rect2d) = 
+    var rect : Rect = (rect.left.cint, rect.top.cint, rect.width.cint, rect.height.cint)
+    renderer.fillRect(addr(rect))
+
+var
+  window: WindowPtr
+  render: RendererPtr
+
+window = createWindow("Game of Life in SDL", 
+    SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 
+    640, 480, 
+    SDL_WINDOW_SHOWN or SDL_WINDOW_RESIZABLE)
+render = createRenderer(window, -1, Renderer_Accelerated or Renderer_PresentVsync or Renderer_TargetTexture)
+
+var
+  evt = sdl2.defaultEvent
+  quit = false
+  freeze = true
+  fpsman: FpsManager
+fpsman.init
+
+let side : uint32 = 5
+let 
+    pixelx = 200u32
+    pixely = 200u32
+
+var
+    current_grid, next_grid : ref[Grid]
+block:
+    var grid = newGrid(pixelx, pixely)
+    grid.rand_init()
+    current_grid = box(grid)
+    next_grid = box(grid)
+
+let bb = newRect2d(0f32, 0f32, float32(side * pixelx), float32(side * pixely))
+let step = 3
+var elapsed_time_sec = 0
+var 
+    uxform : X2d = identity[3, float32]()
+    pan_start : Option[P2d] = none[P2d]()
+
+while not quit:
+    let windowSize = block:
+        var w, h : cint
+        window.getSize(w, h)
+        Rect2d(tl: newP2d(0f32, 0f32), br: newP2d(w.float32, h.float32))
+    while pollEvent(evt):
+        case evt.kind:
+            of QuitEvent:
+                quit = true
+                break
+            of KeyDown:
+                let keyboardEvent = cast[KeyboardEventPtr](addr(evt))
+                case keyboardEvent.keysym.sym.char:
+                    of ' ':
+                        freeze = not freeze
+                    of 'h':
+                        uxform = identity[3, float32]()
+                    else:
+                        discard
+            of MouseButtonDown:
+                let mouseButtonDownEvent = cast[MouseButtonEventPtr](addr(evt))
+                if mouseButtonDownEvent.which == BUTTON_RIGHT:
+                    pan_start = some(newP2d(mouseButtonDownEvent.x.float32, mouseButtonDownEvent.y.float32))
+            of MouseButtonUp:
+                let mouseButtonDownEvent = cast[MouseButtonEventPtr](addr(evt))
+                if mouseButtonDownEvent.which == BUTTON_RIGHT and pan_start.isSome():
+                    let xlation = newP2d(mouseButtonDownEvent.x.float32, mouseButtonDownEvent.y.float32) - pan_start.get()
+                    pan_start = none[P2d]()
+                    uxform = uxform * xlate(xlation.x, xlation.y)
+            of MouseWheel:
+                let mouseWheelEvent = cast[MouseWheelEventPtr](addr(evt))
+                if mouseWheelEvent.y > 0:
+                    uxform = uxform * scale(newP2d(windowSize.width.float32 / 2f32, windowSize.height.float32 / 2f32), 1.1f32, 1.1f32)
+                else:
+                    uxform = uxform * scale(newP2d(windowSize.width.float32 / 2f32, windowSize.height.float32 / 2f32), 0.9f32, 0.9f32)
+            of MouseMotion:
+                let mouseMotionEvent = cast[MouseMotionEventPtr](addr(evt))
+                let position = newP2d(mouseMotionEvent.x.float32, mouseMotionEvent.y.float32)
+
+            else:
+                discard
+
+    let dt = fpsman.getFramerate() / 1000
+
+    render.setDrawColor 0,0,0,255
+    render.clear
+    var
+        x : float32 = bb.left
+        y : float32 = bb.top
+
+    render.setDrawColor 127,127,127,255        
+    let f = min(windowSize.width / bb.width, windowSize.height / bb.height)
+    let xform = xlate(-bb.width / 2.0f32, -bb.height / 2.0f32) * scale(f, f) *
+        xlate(windowSize.width / 2.0f32, windowSize.height / 2.0f32) * uxform
+
+    while x <= bb.width:
+        render.drawLine(newP2d(x, bb.top) * xform, newP2d(x, bb.height) * xform)
+        x += side.float32
+
+    while y <= bb.height:
+        render.drawLine(newP2d(bb.left, y) * xform, newP2d(bb.width, y) * xform)
+        y += side.float32
+  
+    render.setDrawColor 255,255,255,255  
+    for i in 0..<current_grid.columns:
+        for j in 0..<current_grid.rows:
+            if current_grid[][i, j]:
+                render.fillRect(newRect2d((i * side).float32, (j * side).float32, side.float32, side.float32) * xform)
+    render.present
+    fpsman.delay
+    let current_time_sec = fpsman.getFramecount() div step
+    if not freeze and current_time_sec > elapsed_time_sec:
+        elapsed_time_sec = current_time_sec
+        next_step(current_grid[], next_grid[])
+        let tmp = current_grid
+        current_grid = next_grid
+        next_grid = tmp
+
+destroy render
+destroy window
\ No newline at end of file