From 05638483a454a1e66e8af9e5ff17f84f182e9eaf Mon Sep 17 00:00:00 2001
From: Colin McMillen <colin@semicolin.games>
Date: Wed, 19 Feb 2020 13:07:11 -0500
Subject: [PATCH] Support 4-layer parallax-scrolling backgrounds.

GitOrigin-RevId: 58c1d1fee99e56dd656af5bbf628fbdc16d55e14
---
 Shared/Scene.cs    | 25 ++++++++++++++++++++-----
 Shared/Textures.cs |  8 ++++++--
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/Shared/Scene.cs b/Shared/Scene.cs
index c679a1d..e81f734 100644
--- a/Shared/Scene.cs
+++ b/Shared/Scene.cs
@@ -51,14 +51,29 @@ namespace SemiColinGames {
       spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.LinearWrap, null, null);
 
       // Draw background.
-      Color bgBlend = Color.FromNonPremultiplied(new Vector4(1, 1, 1, 0.5f));
-      Rectangle bgSource = new Rectangle(
-        (int) (camera.Left * 0.25), 0, camera.Width, camera.Height);
+
+      // We assume that all backgrounds are the same size; if not, the computation of yOffset needs
+      // to be computed separately for every background.
+      int yOffset = Textures.Background1.Height - camera.Height - 64;
+      Color bgBlend = Color.FromNonPremultiplied(new Vector4(1, 1, 1, 1));
       Rectangle bgTarget = new Rectangle(0, 0, camera.Width, camera.Height);
+
+      Rectangle bgSource = new Rectangle(
+        (int) (camera.Left * 1f / 16), yOffset, camera.Width, camera.Height);
+      spriteBatch.Draw(Textures.Background1, bgTarget, bgSource, bgBlend);
+
+      bgSource = new Rectangle(
+        (int) (camera.Left * 1f / 8), yOffset, camera.Width, camera.Height);
       spriteBatch.Draw(Textures.Background2, bgTarget, bgSource, bgBlend);
+
       bgSource = new Rectangle(
-        (int) (camera.Left * 0.5), 0, camera.Width, camera.Height);
-      spriteBatch.Draw(Textures.Background1, bgTarget, bgSource, bgBlend);
+        (int) (camera.Left * 1f / 4), yOffset, camera.Width, camera.Height);
+      spriteBatch.Draw(Textures.Background3, bgTarget, bgSource, bgBlend);
+
+      bgSource = new Rectangle(
+        (int) (camera.Left * 1f / 2), yOffset, camera.Width, camera.Height);
+      spriteBatch.Draw(Textures.Background4, bgTarget, bgSource, bgBlend);
+
       spriteBatch.End();
 
       // Set up transformation matrix for drawing world objects.
diff --git a/Shared/Textures.cs b/Shared/Textures.cs
index c1f7492..1241fe1 100644
--- a/Shared/Textures.cs
+++ b/Shared/Textures.cs
@@ -8,6 +8,8 @@ namespace SemiColinGames {
 
     public static Texture2D Background1;
     public static Texture2D Background2;
+    public static Texture2D Background3;
+    public static Texture2D Background4;
 
     public static Texture2D Cemetery;
     public static Texture2D Crypt;
@@ -25,8 +27,10 @@ namespace SemiColinGames {
     public static void Load(ContentManager content) {
       Player = content.Load<Texture2D>("sprites/ccg/ninja_female");
 
-      Background1 = content.Load<Texture2D>("backgrounds/anokolisa/grassland_bg1");
-      Background2 = content.Load<Texture2D>("backgrounds/anokolisa/grassland_bg2");
+      Background1 = content.Load<Texture2D>("backgrounds/szadiart/pf4/background1_day");
+      Background2 = content.Load<Texture2D>("backgrounds/szadiart/pf4/background2a_day");
+      Background3 = content.Load<Texture2D>("backgrounds/szadiart/pf4/background3_day");
+      Background4 = content.Load<Texture2D>("backgrounds/szadiart/pf4/background4_day");
 
       Cemetery = content.Load<Texture2D>("tiles/anokolisa/cemetery");
       Crypt = content.Load<Texture2D>("tiles/anokolisa/crypt");