From 028a966856785e316e02246d7dea08016845830f Mon Sep 17 00:00:00 2001
From: Elias Stepanik <40958815+eliasstepanik@users.noreply.github.com>
Date: Sat, 14 Jun 2025 01:32:37 +0200
Subject: [PATCH] Randomize voxel side textures

---
 .../plugins/environment/systems/voxel_system.rs  | 10 +++++-----
 .../plugins/environment/systems/voxels/atlas.rs  | 12 ++++++------
 .../environment/systems/voxels/structure.rs      | 16 ++++++++++++++++
 client/src/plugins/input/systems/voxels.rs       |  4 ++--
 4 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/client/src/plugins/environment/systems/voxel_system.rs b/client/src/plugins/environment/systems/voxel_system.rs
index 117b284..0cee037 100644
--- a/client/src/plugins/environment/systems/voxel_system.rs
+++ b/client/src/plugins/environment/systems/voxel_system.rs
@@ -77,7 +77,7 @@ pub fn generate_voxel_sphere_parallel(octree: &mut SparseVoxelOctree, center: Ve
                             center.y + iy as f32 * step,
                             center.z + iz as f32 * step,
                         );
-                        (pos, Voxel::new([0; 6]))
+                        (pos, Voxel::random_sides())
                     })
                     .collect::<Vec<_>>()
             })
@@ -115,7 +115,7 @@ fn generate_voxel_sphere(octree: &mut SparseVoxelOctree, planet_radius: i32) {
                     let position = Vec3::new(wx, wy, wz);
 
                     // Insert the voxel
-                    let voxel = Voxel::new([0; 6]);
+                    let voxel = Voxel::random_sides();
                     octree.insert(position, voxel);
                 }
             }
@@ -150,7 +150,7 @@ fn generate_voxel_rect(octree: &mut SparseVoxelOctree) {
                 let position = Vec3::new(wx, wy, wz);
 
                 // Insert the voxel
-                let voxel = Voxel::new([0; 6]);
+                let voxel = Voxel::random_sides();
                 octree.insert(position, voxel);
             }
         }
@@ -178,7 +178,7 @@ fn generate_large_plane(octree: &mut SparseVoxelOctree, width: usize, depth: usi
             let position = Vec3::new(wx, wy, wz);
 
             // Insert the voxel
-            let voxel = Voxel::new([0; 6]);
+            let voxel = Voxel::random_sides();
             octree.insert(position, voxel);
         }
     }
@@ -214,7 +214,7 @@ pub fn generate_solid_plane_with_noise(
             for iy in 0..=max_layer {
                 let position = Vec3::new(x * step, iy as f32 * step, z * step);
 
-                let voxel = Voxel::new([0; 6]);
+                let voxel = Voxel::random_sides();
                 octree.insert(position, voxel);
             }
         }
diff --git a/client/src/plugins/environment/systems/voxels/atlas.rs b/client/src/plugins/environment/systems/voxels/atlas.rs
index 71b9eb9..7ae4f28 100644
--- a/client/src/plugins/environment/systems/voxels/atlas.rs
+++ b/client/src/plugins/environment/systems/voxels/atlas.rs
@@ -20,12 +20,12 @@ impl VoxelTextureAtlas {
         let height = tile_size * rows as u32;
         let mut data = vec![0u8; (width * height * 4) as usize];
         let colors = [
-            [255, 0, 0, 255],   // red
-            [0, 255, 0, 255],   // green
-            [0, 0, 255, 255],   // blue
-            [255, 255, 0, 255], // yellow
-            [255, 0, 255, 255], // magenta
-            [0, 255, 255, 255], // cyan
+            [255, 0, 0, 255],   // 0: red
+            [0, 0, 0, 255],     // 1: black
+            [0, 255, 0, 255],   // 2: green
+            [0, 0, 255, 255],   // 3: blue
+            [255, 255, 0, 255], // 4: yellow
+            [255, 0, 255, 255], // 5: magenta
         ];
         for (i, col) in colors.iter().enumerate() {
             let cx = (i % columns) as u32 * tile_size;
diff --git a/client/src/plugins/environment/systems/voxels/structure.rs b/client/src/plugins/environment/systems/voxels/structure.rs
index befe22d..215ee09 100644
--- a/client/src/plugins/environment/systems/voxels/structure.rs
+++ b/client/src/plugins/environment/systems/voxels/structure.rs
@@ -1,4 +1,5 @@
 use bevy::prelude::*;
+use rand::Rng;
 use serde::{Deserialize, Serialize};
 use std::collections::{HashMap, HashSet, VecDeque};
 
@@ -68,6 +69,21 @@ impl Voxel {
     pub fn new(textures: [usize; 6]) -> Self {
         Self { textures }
     }
+
+    /// Generate a voxel with a red top, black bottom and random colors on
+    /// all remaining faces. Assumes the atlas uses index 0 for red, index 1
+    /// for black and indices >=2 for random colors.
+    pub fn random_sides() -> Self {
+        let mut rng = rand::thread_rng();
+        let mut textures = [0usize; 6];
+        // Face order: left, right, bottom, top, back, front
+        textures[3] = 0; // top is red
+        textures[2] = 1; // bottom is black
+        for &i in &[0usize, 1usize, 4usize, 5usize] {
+            textures[i] = rng.gen_range(2..6);
+        }
+        Self { textures }
+    }
 }
 
 pub const NEIGHBOR_OFFSETS: [(f32, f32, f32); 6] = [
diff --git a/client/src/plugins/input/systems/voxels.rs b/client/src/plugins/input/systems/voxels.rs
index bcae7dd..151f578 100644
--- a/client/src/plugins/input/systems/voxels.rs
+++ b/client/src/plugins/input/systems/voxels.rs
@@ -36,7 +36,7 @@ pub fn voxel_system(
 
     if keyboard_input.just_pressed(KeyCode::KeyQ) && window.cursor_options.visible == false {
         for mut octree in octree_query.iter_mut() {
-            octree.insert(transform.translation, Voxel::new([0; 6]));
+            octree.insert(transform.translation, Voxel::random_sides());
         }
     }
     if keyboard_input.just_pressed(KeyCode::F4) {
@@ -106,7 +106,7 @@ pub fn voxel_system(
                             + (normal * Vec3::new(epsilon as f32, epsilon as f32, epsilon as f32));
 
                         // Insert the new voxel
-                        octree.insert(offset_position, Voxel::new([0; 6]));
+                        octree.insert(offset_position, Voxel::random_sides());
                     }
                 }
             }