Add more methods to PF::Line

src/game.cr

@@ -3,7 +3,7 @@ require "./lib_sdl"
 require "./pixel"
 require "./point"
 require "./controller"
-require "./game/fill_triangle"
+require "./game/*"
 
 module PF
   abstract class Game

src/game/fill_triangle.cr

@@ -33,6 +33,7 @@ module PF
 
       0.upto(height) do |y|
         if slope_left == 0
+          # When there is no rise, set the x value directly
           x_left = line_left.p2.x
         else
           x_left = ((y - (line_left.p1.y - p1.y)) / slope_left).round.to_i + line_left.p1.x

src/line.cr

@@ -1,4 +1,8 @@
+require "crystaledge/vector2"
+
 module PF
+  include CrystalEdge
+
   struct Line(T)
     property p1 : Point(T), p2 : Point(T)
 
@@ -18,8 +22,53 @@ module PF
       rise / run
     end
 
+    def inv_slope
+      return 0.0 if rise == 0
+      run / rise
+    end
+
+    def left
+      @p1.x < @p2.x ? @p1.x : @p2.x
+    end
+
+    def right
+      @p1.x > @p2.x ? @p1.x : @p2.x
+    end
+
+    def top
+      @p1.y > @p2.y ? @p2.y : @p1.y
+    end
+
+    def bottom
+      @p1.y > @p2.y ? @p1.y : @p2.y
+    end
+
+    def contains_y?(y)
+      if @p1.y < @p2.y
+        top, bottom = @p1.y, @p2.y
+      else
+        top, bottom = @p2.y, @p1.y
+      end
+
+      y >= top && y <= bottom
+    end
+
+    def y_at(x)
+      return p1.y if slope == 1.0
+      x * slope + p1.y
+    end
+
+    def x_at(y)
+      return p1.x if slope == 0.0
+      (y - p1.y) / slope + p1.x
+    end
+
     def length
-      Math.sqrt((run * 2) + (rise * 2))
+      Math.sqrt((run.abs * 2) + (rise.abs * 2))
+    end
+
+    def to_vector
+      Vector2.new(run.to_f64, rise.to_f64)
     end
   end
 end

src/pixel.cr

@@ -8,6 +8,10 @@ module PF
       new(255, 255, 255)
     end
 
+    def self.black
+      new(0, 0, 0)
+    end
+
     def self.red
       new(255, 0, 0)
     end