Adding texture/background_scrolling example (#91)

Adding textures_background_scrolling example

Signed-off-by: Sebastian Lukas <sisasebbl@googlemail.com>

build.zig

@@ -223,6 +223,11 @@ pub fn build(b: *std.Build) !void {
             .path = "examples/textures/sprite_anim.zig",
             .desc = "Animate a sprite",
         },
+        .{
+            .name = "textures_background_scrolling",
+            .path = "examples/textures/textures_background_scrolling.zig",
+            .desc = "Background scrolling & parallax demo",
+        },
         // .{
         //     .name = "models_loading",
         //     .path = "examples/models/models_loading.zig",

examples/textures/textures_background_scrolling.zig

@@ -0,0 +1,123 @@
+//! # raylib-zig [textures] example - background scrolling
+//!
+//! Example licensed under an unmodified zlib/libpng license, which is an
+//! OSI-certified, BSD-like license that allows static linking with closed
+//! source software
+//!
+//! Copyright (c) Nikolas Wipper 2024
+
+const rl = @import("raylib");
+
+const screen_width = 800;
+const screen_height = 450;
+
+pub fn main() anyerror!void {
+
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    rl.initWindow(screen_width, screen_height, "raylib [textures] example - background scrolling");
+    defer rl.closeWindow(); // Close window and OpenGL context
+
+    // NOTE: Be careful, background width must be equal or bigger than screen width
+    // if not, texture should be draw more than two times for scrolling effect
+    const background = rl.loadTexture("resources/textures/cyberpunk_street_background.png");
+    const midground = rl.loadTexture("resources/textures/cyberpunk_street_midground.png");
+    const foreground = rl.loadTexture("resources/textures/cyberpunk_street_foreground.png");
+    defer rl.unloadTexture(background); // Unload background texture
+    defer rl.unloadTexture(midground); // Unload midground texture
+    defer rl.unloadTexture(foreground); // Unload foreground texture
+
+    var scrolling_back: f32 = 0;
+    var scrolling_mid: f32 = 0;
+    var scrolling_fore: f32 = 0;
+
+    rl.setTargetFPS(60); // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!rl.windowShouldClose()) { // Detect window close button or ESC key
+        // Update
+        //----------------------------------------------------------------------------------
+        scrolling_back -= 0.1;
+        scrolling_mid -= 0.5;
+        scrolling_fore -= 1.0;
+
+        // NOTE: Texture is scaled twice its size, so it sould be considered on scrolling
+        if (scrolling_back <= @as(f32, @floatFromInt(-background.width * 2))) scrolling_back = 0;
+        if (scrolling_mid <= @as(f32, @floatFromInt(-midground.width * 2))) scrolling_mid = 0;
+        if (scrolling_fore <= @as(f32, @floatFromInt(-foreground.width * 2))) scrolling_fore = 0;
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        {
+            rl.beginDrawing();
+            defer rl.endDrawing();
+
+            rl.clearBackground(rl.getColor(0x052c46ff));
+            // Draw background image twice
+            // NOTE: Texture is scaled twice its size
+            rl.drawTextureEx(
+                background,
+                rl.Vector2.init(scrolling_back, 20.0),
+                0.0,
+                2.0,
+                rl.Color.white,
+            );
+            rl.drawTextureEx(
+                background,
+                rl.Vector2.init(@as(f32, @floatFromInt(background.width * 2)) + scrolling_back, 20),
+                0.0,
+                2.0,
+                rl.Color.white,
+            );
+
+            // Draw midground image twice
+            rl.drawTextureEx(
+                midground,
+                rl.Vector2.init(scrolling_mid, 20.0),
+                0.0,
+                2.0,
+                rl.Color.white,
+            );
+            rl.drawTextureEx(
+                midground,
+                rl.Vector2.init(@as(f32, @floatFromInt(midground.width * 2)) + scrolling_mid, 20),
+                0.0,
+                2.0,
+                rl.Color.white,
+            );
+
+            // Draw foreground image twice
+            rl.drawTextureEx(
+                foreground,
+                rl.Vector2.init(scrolling_fore, 70.0),
+                0.0,
+                2.0,
+                rl.Color.white,
+            );
+            rl.drawTextureEx(
+                foreground,
+                rl.Vector2.init(@as(f32, @floatFromInt(foreground.width * 2)) + scrolling_fore, 70),
+                0.0,
+                2.0,
+                rl.Color.white,
+            );
+
+            rl.drawText(
+                "BACKGROUND SCROLLING & PARALLAX",
+                10,
+                10,
+                20,
+                rl.Color.red,
+            );
+            rl.drawText(
+                "(c) Cyberpunk Street Environment by Luis Zuno (@ansimuz)",
+                screen_width - 330,
+                screen_height - 20,
+                10,
+                rl.Color.ray_white,
+            );
+        }
+    }
+}