Add emitter

package.rb

@@ -72,7 +72,7 @@ end
 puts "Copying Info.plist"
 FileUtils.cp 'Info.plist', "#{BUILD_DIR}/"
 
-build_cmd = %{shards build --release --link-flags="-rpath @executable_path/../Frameworks -L #{`brew --prefix sfml`.chomp}/lib/ -mmacosx-version-min=10.14 -headerpad_max_install_names"}
+build_cmd = %{shards build --release --link-flags="-rpath @executable_path/../Frameworks -L #{`brew --prefix sdl2`.chomp}/lib/ -mmacosx-version-min=10.14 -headerpad_max_install_names"}
 puts "Building: `#{build_cmd}`"
 puts `#{build_cmd}`
 

src/asteroids.cr

@@ -50,8 +50,7 @@ class Asteroids < Game
     end
 
     @bullets.each do |bullet|
-      bullet.update
-      bullet.age += dt
+      bullet.update(dt)
     end
 
     @bullets = @bullets.reject { |b| b.age >= 4.0 }

src/bullet.cr

@@ -1,8 +1,9 @@
 class Bullet < Sprite
   property age : Float64 = 0.0
 
-  def update
-    @position += @velocity
+  def update(dt : Float64)
+    update_position(dt)
+    @age += dt
   end
 
   def draw(renderer)

src/lx_game/emitter.cr

@@ -0,0 +1,45 @@
+require "./sprite"
+require "./particle"
+
+module LxGame
+  class Emitter < Sprite
+    property emitting : Bool = true
+    property particles = [] of Particle
+    property max_age : Float64 = 1.0
+    property emit_freq : Float64 = 0.05
+    property strength : Float64 = 50.0
+    @last_emitted : Float64 = 0.0
+    property emit_angle : Float64 = 1.0
+
+    def generate_particle
+      Particle.build do |particle|
+        particle.position = @position
+        direction = rand((@rotation - @emit_angle)..(@rotation + @emit_angle))
+        particle.velocity = @velocity + Vector2.new(Math.cos(direction), Math.sin(direction)) * @strength
+        particle.lifespan = @max_age
+      end
+    end
+
+    def update(dt : Float64)
+      update_position(dt)
+
+      @last_emitted += dt
+
+      if @emitting && @last_emitted >= @emit_freq
+        @last_emitted = 0.0
+        @particles << generate_particle
+      end
+
+      @particles.each { |particle| particle.update(dt) }
+      @particles.reject! { |particle| particle.dead? }
+    end
+
+    def draw(renderer : SDL::Renderer)
+      renderer.draw_color = SDL::Color[255, 255, 0, 255]
+
+      @particles.each do |particle|
+        particle.draw(renderer)
+      end
+    end
+  end
+end

src/lx_game/particle.cr

@@ -0,0 +1,26 @@
+require "./sprite"
+
+module LxGame
+  class Particle < Sprite
+    property age : Float64 = 0.0
+    property lifespan : Float64 = 4.0
+    @dead : Bool = false
+
+    def dead?
+      @age >= @lifespan
+    end
+
+    def update(dt : Float64)
+      return if dead?
+      update_position(dt)
+      @age += dt
+    end
+
+    def draw(renderer : SDL::Renderer)
+      return if dead?
+      brightness = ((@lifespan - @age) / @lifespan) * 255
+      renderer.draw_color = SDL::Color[brightness / 2, brightness / 2, brightness / 2]
+      renderer.draw_point(@position.x.to_i, @position.y.to_i)
+    end
+  end
+end

src/lx_game/sprite.cr

@@ -18,6 +18,12 @@ module LxGame
       @rotation_speed = 0.0
     end
 
+    def update_position(dt : Float64)
+      @rotation += @rotation_speed * dt
+      @position += @velocity * dt
+    end
+
+    abstract def update(dt : Float64)
     abstract def draw(renderer : SDL::Renderer)
   end
 end

src/ship.cr

@@ -1,12 +1,16 @@
 class Ship < VectorSprite
   getter frame : Array(Vector2)
-  @last_fired : Float64
+  @fire_cooldown : Float64 = 0.0
+  @fire_rate : Float64 = 0.2
+  @emitter : Emitter
+  @l_emitter : Emitter
+  @r_emitter : Emitter
 
   def initialize
     super
 
-    @r_engine = 0.03
-    @t_engine = 0.1
+    @r_engine = 10.0
+    @t_engine = 20.0
 
     @frame = [
       Vector2.new(5.0, 0.0),
@@ -14,85 +18,95 @@ class Ship < VectorSprite
       Vector2.new(-3.0, -3.0),
     ]
 
-    @jet_left = [Vector2.new(2.0, -5.0), Vector2.new(2.0, -3.5)]
-    @jet_right = [Vector2.new(2.0, 3.5), Vector2.new(2.0, 5.0)]
-    @jet_rear = [Vector2.new(-7.0, 0.0), Vector2.new(-3.0, 0.0)]
+    @emitter = Emitter.build do |e|
+      e.position = @position
+      e.emit_freq = 0.01
+      e.emit_angle = 0.5
+      e.strength = 50.0
+      e.max_age = 0.25
+    end
 
-    @thrusting_left = false
-    @thrusting_right = false
-    @thrusting_forward = false
+    @l_emitter = Emitter.build do |e|
+      e.position = @position
+      e.emit_freq = 0.01
+      e.emit_angle = 0.3
+      e.strength = 25.0
+      e.max_age = 0.25
+    end
 
-    @last_fired = Time.monotonic.total_milliseconds
+    @r_emitter = Emitter.build do |e|
+      e.position = @position
+      e.emit_freq = 0.01
+      e.emit_angle = 0.3
+      e.strength = 25.0
+      e.max_age = 0.25
+    end
   end
 
   def can_fire?
-    now = Time.monotonic.total_milliseconds
-    now - @last_fired > 100.0
+    @fire_cooldown <= 0.0
   end
 
   def fire
-    @last_fired = Time.monotonic.total_milliseconds
+    @fire_cooldown = @fire_rate
+    @velocity.x -= Math.cos(@rotation) * 3.0
+    @velocity.y -= Math.sin(@rotation) * 3.0
     Bullet.build do |bullet|
       bullet.position = project_points([@frame[0]]).first
-      bullet.velocity = @velocity + Vector2.new(Math.cos(@rotation), Math.sin(@rotation)) * 0.1
+      bullet.velocity = @velocity + Vector2.new(Math.cos(@rotation), Math.sin(@rotation)) * 100.0
     end
   end
 
   def rotate_right(dt : Float64, amount = @r_engine)
-    @thrusting_left = true
+    @l_emitter.emitting = true
     @rotation_speed += amount * dt
   end
 
   def rotate_left(dt : Float64, amount = @r_engine)
-    @thrusting_right = true
+    @r_emitter.emitting = true
     @rotation_speed -= amount * dt
   end
 
   def thrust(dt : Float64)
-    @thrusting_forward = true
+    @emitter.emitting = true
     @velocity.x += Math.cos(@rotation) * dt * @t_engine
     @velocity.y += Math.sin(@rotation) * dt * @t_engine
   end
 
   def update(dt : Float64)
-    @rotation += @rotation_speed
-    @position += @velocity
+    @fire_cooldown -= dt unless can_fire?
+    update_position(dt)
 
-    # @rotation_speed = 0.0 if @rotation_speed < 0.001 && @rotation_speed > -0.001
-    # rotate_left(dt, 0.01) if @rotation_speed >= 0.01
-    # rotate_right(dt, 0.01) if @rotation_speed <= -0.01
+    @emitter.update(dt)
+    @emitter.position = project_points([Vector2.new(-3.0, 0.0)]).first
+    @emitter.velocity = @velocity
+    @emitter.rotation = @rotation - Math::PI
+
+    @l_emitter.update(dt)
+    @l_emitter.position = project_points([Vector2.new(3.0, -1.0)]).first
+    @l_emitter.velocity = @velocity
+    @l_emitter.rotation = @rotation - 1.5
+
+    @r_emitter.update(dt)
+    @r_emitter.position = project_points([Vector2.new(3.0, 1.0)]).first
+    @r_emitter.velocity = @velocity
+    @r_emitter.rotation = @rotation + 1.5
   end
 
   def draw(renderer)
+    @emitter.draw(renderer)
+    @emitter.emitting = false
+    @l_emitter.draw(renderer)
+    @l_emitter.emitting = false
+    @r_emitter.draw(renderer)
+    @r_emitter.emitting = false
     frame = project_points(@frame)
 
     renderer.draw_color = SDL::Color[128, 128, 128, 255]
-
-    if @thrusting_left
-      @thrusting_left = false
-      jet_left = project_points(@jet_left, @rotation + rand(-0.5..0.5))
-      draw_line(renderer, jet_left[0], jet_left[1])
-    end
-
-    if @thrusting_right
-      @thrusting_right = false
-      jet_right = project_points(@jet_right, @rotation + rand(-0.5..0.5))
-      draw_line(renderer, jet_right[0], jet_right[1])
-    end
-
-    if @thrusting_forward
-      @thrusting_forward = false
-      jet_rear = project_points(@jet_rear, @rotation + rand(-0.5..0.5))
-      draw_line(renderer, jet_rear[0], jet_rear[1])
-    end
-
     renderer.draw_color = SDL::Color[255, 255, 255, 255]
 
     draw_line(renderer, frame[0], frame[1])
     draw_line(renderer, frame[1], frame[2])
     draw_line(renderer, frame[2], frame[0])
-
-    # renderer.draw_color = SDL::Color[255, 255, 0, 255]
-    # renderer.draw_point(@position.x.to_i, @position.y.to_i)
   end
 end