From 94f857a6958fb8ad328db6b9389ab06f1d3b860e Mon Sep 17 00:00:00 2001
From: Christian Semmler <mail@csemmler.com>
Date: Sun, 1 Feb 2026 15:53:47 -0800
Subject: [PATCH] Add transparency support to vehicle part rendering

Apply mesh alpha values from WDB to Three.js materials. In the original
game, alpha=0 means opaque while alpha>0 enables transparency. Disable
depthWrite for transparent meshes to prevent z-fighting.
---
 src/core/rendering/VehiclePartRenderer.js | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/core/rendering/VehiclePartRenderer.js b/src/core/rendering/VehiclePartRenderer.js
index 22df995..607d908 100644
--- a/src/core/rendering/VehiclePartRenderer.js
+++ b/src/core/rendering/VehiclePartRenderer.js
@@ -137,13 +137,22 @@ export class VehiclePartRenderer {
 
                 let material;
 
+                // Get alpha from mesh properties
+                // In the original game: alpha = 0 means opaque, alpha > 0 means transparent
+                const meshAlpha = mesh.properties?.alpha || 0;
+                const isTransparent = meshAlpha > 0;
+                const opacity = isTransparent ? meshAlpha : 1;
+
                 if (isColorable) {
                     // Mesh has INH prefix - use the LEGO color
                     material = new THREE.MeshStandardMaterial({
                         color: legoColor,
                         side: THREE.DoubleSide,
                         roughness: 0.7,
-                        metalness: 0.1
+                        metalness: 0.1,
+                        transparent: isTransparent,
+                        opacity: opacity,
+                        depthWrite: !isTransparent
                     });
                     this.colorableMeshes.push(null); // Placeholder, will set after mesh creation
                 } else if (hasUVs && meshTextureName && this.textures.has(meshTextureName)) {
@@ -152,7 +161,10 @@ export class VehiclePartRenderer {
                         map: this.textures.get(meshTextureName),
                         side: THREE.DoubleSide,
                         roughness: 0.8,
-                        metalness: 0.1
+                        metalness: 0.1,
+                        transparent: isTransparent,
+                        opacity: opacity,
+                        depthWrite: !isTransparent
                     });
                 } else {
                     // Fallback to mesh's vertex color
@@ -161,7 +173,10 @@ export class VehiclePartRenderer {
                         color: new THREE.Color(meshColor.r / 255, meshColor.g / 255, meshColor.b / 255),
                         side: THREE.DoubleSide,
                         roughness: 0.8,
-                        metalness: 0.1
+                        metalness: 0.1,
+                        transparent: isTransparent,
+                        opacity: opacity,
+                        depthWrite: !isTransparent
                     });
                 }