Add initial implementation of game mechanics and resources management

Shaders/corruption_shader.gdshader

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+shader_type canvas_item;
+
+// The color of the healthy terrain you want to target.
+uniform vec4 terrain_color : source_color = vec4(0.0, 1.0, 0.0, 1.0);
+// The color the terrain will turn into as it gets corrupted.
+uniform vec4 corrupted_color : source_color = vec4(0.3, 0.1, 0.2, 1.0);
+// This value will be controlled by your C# script (from 0.0 to 1.0).
+uniform float corruption_level : hint_range(0.0, 1.0);
+// A small tolerance to catch pixels that aren't *exactly* the terrain color.
+uniform float tolerance : hint_range(0.0, 0.5) = 0.1;
+
+void fragment() {
+    // Get the original color of the pixel from the sprite's texture.
+    vec4 original_color = texture(TEXTURE, UV);
+
+    // Calculate the difference between this pixel's color and the healthy terrain color.
+    // The distance() function is great for comparing colors.
+    float color_difference = distance(original_color.rgb, terrain_color.rgb);
+
+    // Check if the difference is within our tolerance.
+    if (color_difference < tolerance) {
+        // If it's a terrain pixel, mix the original terrain color with the
+        // corrupted color based on the corruption_level.
+        vec3 final_color = mix(terrain_color.rgb, corrupted_color.rgb, corruption_level);
+        COLOR = vec4(final_color, original_color.a);
+    } else {
+        // If it's not a terrain pixel (i.e., it's ocean), leave it unchanged.
+        COLOR = original_color;
+    }
+}

Shaders/corruption_shader.gdshader.uid

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+uid://bf8nk145fjkgh