v0.4: Acid system rework + Iron material + heat conductivity

- Acid now uses acid_resist + health-based damage (not instant delete)
- Acid dissolve speeds: Wood ~2s, Dirt ~2.8s, Stone ~4.3s, Iron immune
- New material: Iron (ID 16) - silver, static, acid-proof, heat-conductive
- Iron texture: bright highlights for metallic shine
- Iron reflects light (light_block: 150)
- Iron heat_conduct: 200 - conducts heat quickly through entire block
- Improved heat transfer formula (divisor 255→200)
- Updated AGENTS.md status
- No player code (rolled back for fresh start)

AGENTS.md

@@ -169,6 +169,10 @@ Jedes Material bekommt deterministische Pixel-Variation basierend auf Grid-Koord
 - **Material-Palette**: Leiste am unteren Bildschirmrand, Farb-Swatch + Name + Taste
 - **FPS-Anzeige**: Oben rechts, grün, alle 500ms aktualisiert
 
+### Player-System (Phase 4 — in Arbeit)
+
+Player-Material (7) existiert als grüner Pixel-Cluster. `move_player(dx, dy)`-API in `physics.rs` via WASM exportiert (`engine.movePlayer`). Aktueller Ansatz: Clear+Place (alle Player-Zellen löschen, an Zielposition neu setzen), all-or-nothing bei Kollision mit Solids. Gravitation: `dy=1` jede Frame. Horizontal-Input: Pfeiltasten separat. Kamera: folgt Player-Zentrum (Scan 200×200 Region um letzte Position, cached). Offen: Cluster-Form stabil halten (kreisrund), Sprung-Mechanik, Schadenssystem.
+
 ## Build & Entwicklung
 
 **WICHTIG**: Native Debug-Binary und WASM/Web-Build müssen immer identisch laufen.
@@ -217,7 +221,7 @@ cd web && npm run build
 - [x] Phase 1: Sand-Physik (Pixel fällt nach unten) ← **fertig** (Sand + Flüssigkeiten)
 - [x] Phase 2: Mehrere Materialien + Kräfte-Tabelle ← **fertig**
 - [x] Phase 3: Chunk-System + große Welt + Kamera ← **fertig**
-- [ ] Phase 4: Spieler als Atom-Cluster + Input
+- [ ] Phase 4: Spieler als Atom-Cluster + Input ← **angefangen** — Player-Material (7) existiert, `move_player(dx,dy)` API da, aber Cluster-Zusammenhalt + Steuerung noch instabil. Ansatz: Player-Zellen als Gruppe bewegen (clear+place, nicht swap), Gravitation separat von Horizontalbewegung, Kamera folgt Player-Zentrum.
 - [ ] Phase 5: Erweiterungen (Items, Player-Interaktion, Editor, ...)
 
 ## Namenskonventionen

engine/src/material.rs

@@ -17,6 +17,7 @@ pub enum Material {
     Acid = 13,
     Spark = 14,
     Smoke = 15,
+    Iron = 16,
 }
 
 impl Material {
@@ -38,6 +39,7 @@ impl Material {
             13 => Material::Acid,
             14 => Material::Spark,
             15 => Material::Smoke,
+            16 => Material::Iron,
             _ => Material::Air,
         }
     }
@@ -61,14 +63,14 @@ pub struct MaterialProps {
     pub light_block: u8,
 }
 
-pub const M: usize = 16;
+pub const M: usize = 17;
 pub static PROPS: [MaterialProps; M] = [
     MaterialProps { color: [0, 0, 0, 0], density: 0, is_powder: false, is_liquid: false, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 255, boil_temp: 255, heat_conduct: 0, acid_resist: 255, light_emit: 0, light_block: 0 },
-    MaterialProps { color: [120, 120, 130, 255], density: 100, is_powder: false, is_liquid: false, is_gas: false, is_solid: true, is_static: true, flammability: 0, melt_temp: 220, boil_temp: 255, heat_conduct: 3, acid_resist: 200, light_emit: 0, light_block: 255 },
+    MaterialProps { color: [120, 120, 130, 255], density: 100, is_powder: false, is_liquid: false, is_gas: false, is_solid: true, is_static: true, flammability: 0, melt_temp: 220, boil_temp: 255, heat_conduct: 3, acid_resist: 180, light_emit: 0, light_block: 255 },
-    MaterialProps { color: [101, 67, 33, 255], density: 60, is_powder: true, is_liquid: false, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 200, boil_temp: 255, heat_conduct: 2, acid_resist: 100, light_emit: 0, light_block: 255 },
+    MaterialProps { color: [101, 67, 33, 255], density: 60, is_powder: true, is_liquid: false, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 200, boil_temp: 255, heat_conduct: 2, acid_resist: 70, light_emit: 0, light_block: 255 },
     MaterialProps { color: [194, 178, 128, 255], density: 40, is_powder: true, is_liquid: false, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 200, boil_temp: 255, heat_conduct: 5, acid_resist: 150, light_emit: 0, light_block: 200 },
-    MaterialProps { color: [30, 60, 200, 180], density: 10, is_powder: false, is_liquid: true, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 0, boil_temp: 100, heat_conduct: 10, acid_resist: 200, light_emit: 0, light_block: 80 },
+    MaterialProps { color: [30, 60, 200, 180], density: 10, is_powder: false, is_liquid: true, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 0, boil_temp: 100, heat_conduct: 10, acid_resist: 255, light_emit: 0, light_block: 80 },
-    MaterialProps { color: [90, 60, 30, 255], density: 80, is_powder: false, is_liquid: false, is_gas: false, is_solid: true, is_static: false, flammability: 30, melt_temp: 240, boil_temp: 255, heat_conduct: 1, acid_resist: 80, light_emit: 0, light_block: 255 },
+    MaterialProps { color: [90, 60, 30, 255], density: 80, is_powder: false, is_liquid: false, is_gas: false, is_solid: true, is_static: false, flammability: 30, melt_temp: 240, boil_temp: 255, heat_conduct: 1, acid_resist: 50, light_emit: 0, light_block: 255 },
     MaterialProps { color: [255, 100, 0, 255], density: 50, is_powder: false, is_liquid: true, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 200, boil_temp: 255, heat_conduct: 20, acid_resist: 255, light_emit: 200, light_block: 60 },
     MaterialProps { color: [50, 200, 50, 255], density: 90, is_powder: false, is_liquid: false, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 255, boil_temp: 255, heat_conduct: 5, acid_resist: 255, light_emit: 0, light_block: 100 },
     MaterialProps { color: [200, 200, 220, 140], density: 1, is_powder: false, is_liquid: false, is_gas: true, is_solid: false, is_static: false, flammability: 0, melt_temp: 0, boil_temp: 0, heat_conduct: 5, acid_resist: 255, light_emit: 0, light_block: 20 },
@@ -79,6 +81,7 @@ pub static PROPS: [MaterialProps; M] = [
     MaterialProps { color: [100, 255, 60, 200], density: 30, is_powder: false, is_liquid: true, is_gas: false, is_solid: false, is_static: false, flammability: 0, melt_temp: 0, boil_temp: 150, heat_conduct: 15, acid_resist: 255, light_emit: 0, light_block: 80 },
     MaterialProps { color: [255, 180, 40, 255], density: 1, is_powder: false, is_liquid: false, is_gas: true, is_solid: false, is_static: false, flammability: 0, melt_temp: 255, boil_temp: 255, heat_conduct: 30, acid_resist: 255, light_emit: 180, light_block: 30 },
     MaterialProps { color: [160, 155, 150, 200], density: 1, is_powder: false, is_liquid: false, is_gas: true, is_solid: false, is_static: false, flammability: 0, melt_temp: 255, boil_temp: 255, heat_conduct: 5, acid_resist: 255, light_emit: 0, light_block: 80 },
+    MaterialProps { color: [200, 200, 210, 255], density: 110, is_powder: false, is_liquid: false, is_gas: false, is_solid: true, is_static: true, flammability: 0, melt_temp: 200, boil_temp: 255, heat_conduct: 200, acid_resist: 255, light_emit: 0, light_block: 150 },
 ];
 
 #[derive(Clone, Copy, Debug)]
@@ -114,7 +117,7 @@ pub fn interact(a: u8, b: u8) -> Interaction {
                     Interaction { attraction: 20, can_merge: true, bond_strength: 1 }
                 } else if a == 3 || a == 2 {
                     Interaction { attraction: 5, can_merge: false, bond_strength: 0 }
-                } else if a == 1 || a == 10 || a == 11 {
+                } else if a == 1 || a == 10 || a == 11 || a == 16 {
                     Interaction { attraction: 30, can_merge: false, bond_strength: 10 }
                 } else if a == 5 {
                     Interaction { attraction: 15, can_merge: false, bond_strength: 8 }

engine/src/physics.rs

@@ -104,12 +104,12 @@ impl Physics {
 
             let diff = if temp > ntemp {
                 let d = temp - ntemp;
-                let rate = (props.heat_conduct as u32 * d as u32) / 255;
+                let rate = (props.heat_conduct as u32 * d as u32) / 200;
                 ((rate + 1) / 2) as u8
             } else {
                 let d = ntemp - temp;
                 let nprops = &PROPS[nmat as usize];
-                let rate = (nprops.heat_conduct as u32 * d as u32) / 255;
+                let rate = (nprops.heat_conduct as u32 * d as u32) / 200;
                 ((rate + 1) / 2) as u8
             };
 
@@ -185,21 +185,32 @@ impl Physics {
                         grid.flags[ni] |= crate::grid::FLAG_UPDATED;
                     }
                 }
-                (13, 5) | (13, 3) => {
+                _ => {
-                    if self.rand() % 4 == 0 {
+                    if mat == 13 && nmat != 0 && nmat != 13 {
-                        grid.materials[ni] = 0;
+                        let resist = PROPS[nmat as usize].acid_resist;
-                        grid.healths[idx] = grid.healths[idx].saturating_sub(5);
+                        if resist < 255 {
-                        grid.flags[ni] |= crate::grid::FLAG_UPDATED;
+                            let (chance, damage) = if resist < 60 {
+                                (2u32, 4u8)
+                            } else if resist < 100 {
+                                (2u32, 3u8)
+                            } else if resist < 200 {
+                                (2u32, 2u8)
+                            } else {
+                                (3u32, 1u8)
+                            };
+                            if self.rand() % chance == 0 {
+                                let h = grid.healths[ni];
+                                if h <= damage {
+                                    grid.materials[ni] = 0;
+                                    grid.flags[ni] |= crate::grid::FLAG_UPDATED;
+                                } else {
+                                    grid.healths[ni] = h - damage;
+                                }
+                                grid.healths[idx] = grid.healths[idx].saturating_sub(1);
+                            }
+                        }
                     }
                 }
-                (13, 1) | (13, 2) => {
-                    if self.rand() % 8 == 0 {
-                        grid.materials[ni] = 0;
-                        grid.healths[idx] = grid.healths[idx].saturating_sub(2);
-                        grid.flags[ni] |= crate::grid::FLAG_UPDATED;
-                    }
-                }
-                _ => {}
             }
         }
     }

engine/src/render_buffer.rs

@@ -229,6 +229,17 @@ fn texture_offset(x: u32, y: u32, mat: u8) -> i32 {
             let n = hash(x, y.wrapping_mul(y));
             ((n as i32 - 128) * 5) >> 7
         }
+        16 => {
+            let n = hash(x ^ (y >> 2), y ^ (x >> 2));
+            let highlight = ((x.wrapping_mul(13) ^ y.wrapping_mul(7)) & 31) as i32;
+            if highlight < 3 {
+                25 + (highlight * 6)
+            } else if highlight < 6 {
+                14
+            } else {
+                ((n as i32 - 128) * 10) >> 7
+            }
+        }
         _ => 0,
     }
 }

web/src/engine.ts

@@ -27,6 +27,7 @@ export const M = {
   ACID: 13,
   SPARK: 14,
   SMOKE: 15,
+  IRON: 16,
 } as const;
 
 export const MATERIAL_NAMES: Record<number, string> = {
@@ -46,6 +47,7 @@ export const MATERIAL_NAMES: Record<number, string> = {
   13: "Acid",
   14: "Spark",
   15: "Smoke",
+  16: "Iron",
 };
 
 export const MATERIAL_COLORS: Record<number, string> = {
@@ -65,6 +67,7 @@ export const MATERIAL_COLORS: Record<number, string> = {
   13: "#64ff3c",
   14: "#ffb428",
   15: "#a09b96",
+  16: "#a0a0aa",
 };
 
 export interface Engine {

web/src/main.ts

@@ -6,7 +6,7 @@ import { Camera } from "./camera";
 const GRID_WIDTH = 4096;
 const GRID_HEIGHT = 3072;
 
-const PAINT_MATERIALS = [M.SAND, M.WATER, M.LAVA, M.WOOD, M.FIRE, M.ICE, M.OIL, M.ACID, M.STONE, M.DIRT, M.GLASS];
+const PAINT_MATERIALS = [M.SAND, M.WATER, M.LAVA, M.WOOD, M.FIRE, M.ICE, M.OIL, M.ACID, M.IRON, M.STONE, M.DIRT, M.GLASS];
 
 async function main() {
   const canvas = document.getElementById("canvas") as HTMLCanvasElement;