feat Create 2D animations

* Rakefile: Add subfolders to the lib directory.
* lib/animation/discrete.rb: Create a class for discrete animations.
This class needs tests.
* lib/animation/frame_2d.rb: Create a 2D frame to be used with discrete
animations

2 files changed, 89 insertions, 0 deletions

diff --git a/lib/animation/discrete.rb b/lib/animation/discrete.rb
new file mode 100644
index 0000000..118bf0f
--- /dev/null
+++ b/lib/animation/discrete.rb
@@ -0,0 +1,58 @@
+# Copyright 2022-2023 Frederico de Oliveira Linhares
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+module CandyGear::Animation
+  class Discrete
+    Step = Struct.new(:duration, :obj);
+
+    def initialize(steps, looping=true)
+      @steps = steps.map { Step.new(_1[0], _1[1]); };
+      @looping = looping;
+
+      self.reset();
+    end
+
+    def tick()
+      step = @steps[@index];
+
+      return step.obj if @sequence_over;
+
+      @current_time += 1;
+
+      if @current_time >= step.duration then
+        @current_time = 0;
+        @index += 1;
+
+        if @index >= @steps.size then
+          if @looping then
+            @index = 0; # It is looping, go back to first step.
+          else
+            @index -= 1;
+            @sequence_over = true;
+          end
+        end
+      end
+
+      return step.obj;
+    end
+
+    def obj() = @steps[@index].obj;
+
+    def reset()
+      @index = 0;
+      @current_time = 0;
+      @sequence_over = false;
+    end
+  end
+end
diff --git a/lib/animation/frame_2d.rb b/lib/animation/frame_2d.rb
new file mode 100644
index 0000000..5d0b335
--- /dev/null
+++ b/lib/animation/frame_2d.rb
@@ -0,0 +1,31 @@
+# Copyright 2022-2023 Frederico de Oliveira Linhares
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+module CandyGear
+  module Animation
+    class Frame2D
+      def initialize(sprite, x, y, width, height)
+        @position = Vector4D.new(x, y, width, height);
+        @sprite = sprite;
+      end
+
+      def draw(view, pivot_x, pivot_y)
+        @sprite.draw(
+          view,
+          @position.x + pivot_x, @position.y + pivot_y,
+          @position.w, @position.h);
+      end
+    end
+  end
+end