From 38dbaea4af6d426a1b40abe4fba16fad28e00015 Mon Sep 17 00:00:00 2001
From: Alex Clink <alexclink@gmail.com>
Date: Mon, 24 Jan 2022 22:03:49 -0500
Subject: [PATCH] Add fill_circle drawing method

---
 src/game.cr               |  4 ++--
 src/sprite.cr             | 25 +++++++++++++++++++++++++
 src/sprite/draw_line.cr   |  7 +++++++
 src/sprite/fill_circle.cr | 34 ++++++++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+), 2 deletions(-)
 create mode 100644 src/sprite/fill_circle.cr

diff --git a/src/game.cr b/src/game.cr
index 86c1c93..15e2024 100644
--- a/src/game.cr
+++ b/src/game.cr
@@ -17,8 +17,8 @@ module PF
 
     @viewport : Vector2(Int32)? = nil
 
-    delegate :draw_point, :draw_line, :draw_circle, :draw_triangle, :draw_rect, :draw_shape,
-      :fill_triangle, :fill_rect, :fill_shape, to: @screen
+    delegate :draw_point, :draw_line, :scan_line, :draw_circle, :draw_triangle, :draw_rect, :draw_shape,
+      :fill_triangle, :fill_rect, :fill_circle, :fill_shape, to: @screen
 
     @fps_lasttime : Float64 = Time.monotonic.total_milliseconds # the last recorded time.
     @fps_current : UInt32 = 0                                   # the current FPS.
diff --git a/src/sprite.cr b/src/sprite.cr
index e58a97a..76b3d68 100644
--- a/src/sprite.cr
+++ b/src/sprite.cr
@@ -4,6 +4,26 @@ require "./sprite/*"
 
 module PF
   class Sprite
+    def self.load_tiles(path, tile_width, tile_height)
+      sheet = Sprite.new(path)
+      sprites = [] of Sprite
+
+      tiles_x = sheet.width // tile_width
+      tiles_y = sheet.height // tile_height
+
+      0.upto(tiles_x - 1) do |tx|
+        0.upto(tiles_y - 1) do |ty|
+          sx = tx * tile_width
+          sy = ty * tile_height
+          sprite = Sprite.new(tile_width, tile_height)
+          sheet.draw_to(sprite, Vector[sx, sy], Vector[tile_width, tile_height], Vector[0, 0])
+          sprites << sprite
+        end
+      end
+
+      sprites
+    end
+
     property surface : SDL::Surface
 
     delegate :fill, :lock, :format, to: @surface
@@ -59,6 +79,11 @@ module PF
       draw_to(dest, at.x, at.y)
     end
 
+    # Draw this sprite to another given a source rect and destination
+    def draw_to(sprite : Sprite, source : Vector2(Int), size : Vector2(Int), dest : Vector2(Int))
+      @surface.blit(sprite.surface, SDL::Rect.new(source.x, source.y, size.x, size.y), SDL::Rect.new(dest.x, dest.y, size.x, size.y))
+    end
+
     # Raw access to the pixels as a Slice
     def pixels
       Slice.new(@surface.pixels.as(Pointer(UInt32)), width * height)
diff --git a/src/sprite/draw_line.cr b/src/sprite/draw_line.cr
index a38e493..a6f9a98 100644
--- a/src/sprite/draw_line.cr
+++ b/src/sprite/draw_line.cr
@@ -54,5 +54,12 @@ module PF
     def draw_line(line : Line, pixel : Pixel = Pixel.new)
       draw_line(line.p1.to_i32, line.p2.to_i32, pixel)
     end
+
+    # Draw a horizontal line to a certain *width*
+    def scan_line(x : Int, y : Int, width : Int, pixel : Pixel = Pixel.new)
+      0.upto(width) do |n|
+        draw_point(x + n, y, pixel)
+      end
+    end
   end
 end
diff --git a/src/sprite/fill_circle.cr b/src/sprite/fill_circle.cr
new file mode 100644
index 0000000..0c13e1b
--- /dev/null
+++ b/src/sprite/fill_circle.cr
@@ -0,0 +1,34 @@
+module PF
+  class Sprite
+    # Fill a circle using Bresenham’s Algorithm
+    def fill_circle(cx : Int, cy : Int, r : Int, pixel : Pixel = Pixel.new)
+      x, y = 0, r
+      balance = 0 - r
+
+      while x <= y
+        p0 = cx - x
+        p1 = cx - y
+
+        w0 = x + x
+        w1 = y + y
+
+        scan_line(p0, cy + y, w0, pixel)
+        scan_line(p0, cy - y, w0, pixel)
+        scan_line(p1, cy + x, w1, pixel)
+        scan_line(p1, cy - x, w1, pixel)
+
+        x += 1
+        balance += x + x
+
+        if balance >= 0
+          y -= 1
+          balance -= (y + y)
+        end
+      end
+    end
+
+    def fill_circle(c : Vector2(Int), r : Int, pixel : Pixel = Pixel.new)
+      fill_circle(c.x, c.y, r, pixel)
+    end
+  end
+end