Add initial prototype.

3-mid/opengl/source/lean/renderer/opengl-impostor-simple.adb

@@ -0,0 +1,109 @@
+with
+     openGL.Camera,
+     openGL.Texture,
+
+     ada.unchecked_Deallocation;
+
+package body openGL.Impostor.simple
+is
+
+   procedure free (Self : in out View)
+   is
+      procedure deallocate is new ada.unchecked_Deallocation (Item'Class, View);
+   begin
+      if Self /= null
+      then
+         destroy    (Self.all);
+         deallocate (Self);
+      end if;
+   end free;
+
+
+
+   overriding
+   function current_Camera_look_at_Rotation (Self : in Item) return Matrix_3x3
+   is
+   begin
+      return Self.current_Camera_look_at_Rotation;
+   end current_Camera_look_at_Rotation;
+
+
+
+   overriding
+   function update_Required (Self : access Item;   the_Camera : access Camera.item'Class) return Boolean
+   is
+      use linear_Algebra_3d;
+   begin
+      -- Look directly at target so it will be rendered in the centre of the viewport.
+      --
+      Self.current_Camera_look_at_Rotation := get_Rotation (look_at (the_Camera.Site,
+                                                                     get_Translation (Self.Target.Transform),
+                                                                     --  get_Translation (Self.Target.model_Transform),
+                                                                     [0.0, 1.0, 0.0]));
+      Self.current_pixel_Region := Self.get_pixel_Region (camera_Spin                 => Self.current_Camera_look_at_Rotation,
+                                                          camera_Site                 => the_Camera.Site,
+                                                          camera_projection_Transform => the_Camera.projection_Transform,
+                                                          camera_Viewport             => the_Camera.Viewport);
+      declare
+         update_Required : Boolean := Self.general_Update_required (the_Camera.Site,
+                                                                    Self.current_pixel_Region);
+      begin
+         if         not update_Required
+           and then Self.size_Update_required (Self.current_pixel_Region)
+         then
+            update_Required := True;
+         end if;
+
+         if Update_required
+         then
+            Self.current_Width_pixels  := Self.current_pixel_Region.Width;       -- Cache current state.
+            Self.current_Height_pixels := Self.current_pixel_Region.Height;
+
+            Self.current_copy_X        := Self.current_pixel_Region.X;
+            Self.current_copy_Y        := Self.current_pixel_Region.Y;
+
+            Self.current_copy_Width    := Self.current_pixel_Region.Width;
+            Self.current_copy_Height   := Self.current_pixel_Region.Height;
+         end if;
+
+         return update_Required;
+      end;
+   end update_Required;
+
+
+
+   overriding
+   procedure pre_update (Self : in out Item;   the_Camera : access Camera.item'Class)
+   is
+   begin
+      Self.camera_world_Rotation_original := the_Camera.Spin;
+
+      the_Camera.Spin_is (Self.current_Camera_look_at_Rotation);
+   end pre_update;
+
+
+
+   overriding
+   procedure update (Self : in out Item;   the_Camera   : access Camera.item'Class;
+                                           texture_Pool : in     Texture.Pool_view)
+   is
+      world_Rotation_original : constant Matrix_3x3 := the_Camera.Spin;
+   begin
+      the_Camera.Spin_is (Self.current_Camera_look_at_Rotation);
+
+      Impostor.item (Self).update (the_Camera, texture_Pool);   -- Base class 'update'.
+
+      the_Camera.Spin_is (world_Rotation_original);
+   end update;
+
+
+
+   overriding
+   procedure post_update (Self : in out Item;   the_Camera : access Camera.item'Class)
+   is
+   begin
+      the_Camera.Spin_is (Self.camera_world_Rotation_original);
+   end post_update;
+
+
+end openGL.Impostor.simple;