Fixed vehicle rendering

assets/blender/scripts/gen_vehicle.py

@@ -275,14 +275,17 @@ for m in used_mats:
         print("gen_vehicle: unpacked texture '%s' -> %s" %
               (img.name, tex_name))
 
-# --- merged single material + ID map (CAR_MODELING.md) ---
-# Every mesh part is re-materialized onto a single material named
-# <base> so blender2ogre emits ONE submesh per part, and the exporter's
-# fixed-function .material is replaced with the VehicleIdMap shader
-# materials after the export.  The ID map texture shares the color
-# atlas UV space (all parts MUST use that one UV space with no texel
-# shared between materials; fix the blend if not) and marks each
-# fragment: red = paint (atlas color), green = bloom (lights),
+# --- merged paint material + separate glass material (CAR_MODELING.md) ---
+# Every mesh part is re-materialized onto TWO materials: <base> for
+# paint/bloom faces and <base>-glass for glass faces, so blender2ogre
+# emits one submesh per part (glass-less parts) or two (glass last).
+# A single merged transparent submesh forced the WHOLE part (interior
+# included) into the transparent render queue, where the depth-writing
+# window glass culled interior parts that sorted behind it ("holes" in
+# the cabin with the road showing through).  The ID map texture shares
+# the color atlas UV space (all parts MUST use that one UV space with
+# no texel shared between materials; fix the blend if not) and marks
+# each fragment: red = paint (atlas color), green = bloom (lights),
 # blue = glass.
 IDMAP_SIZE = 512
 
@@ -367,10 +370,10 @@ def bake_idmap(mesh_datas, path):
 
 
 def move_glass_faces_last():
-    """Re-order each mesh so glass faces export last: with the merged
-    transparent material (depth_write on) the cabin stays visible
-    through the windows only if glass triangles draw after the
-    interior."""
+    """Re-order each mesh so glass faces export last.  With glass on
+    its own material slot (see the consolidation below) blender2ogre
+    groups faces into submeshes by material anyway; the sort just
+    keeps the glass submesh's triangles contiguous at the end."""
     for obj in bpy.data.objects:
         if obj.type != 'MESH':
             continue
@@ -410,13 +413,35 @@ for obj in bpy.data.objects:
 move_glass_faces_last()
 bake_idmap(all_mesh_datas, os.path.join(outdir, base + "-idmap.png"))
 
-merged_mat = bpy.data.materials.new(base)
+merged_mat = bpy.data.materials.get(base)
+if merged_mat is None:
+    merged_mat = bpy.data.materials.new(base)
 merged_mat.use_nodes = True
+# The blend already HAS a "<base>-glass" material (source materials are
+# renamed to <base>-<material>); reuse it — materials.new() would
+# silently create "<base>-glass.001", and the exported submesh material
+# name must match the .material template exactly.
+glass_mat = bpy.data.materials.get(base + "-glass")
+if glass_mat is None:
+    glass_mat = bpy.data.materials.new(base + "-glass")
+glass_mat.use_nodes = True
 for me in all_mesh_datas:
+    # materials.clear() zeroes every polygon's material_index, so
+    # classify faces against the original slots first.
+    glass_face = [
+        p.material_index < len(me.materials) and
+        me.materials[p.material_index] is not None and
+        "glass" in me.materials[p.material_index].name.lower()
+        for p in me.polygons
+    ]
     me.materials.clear()
     me.materials.append(merged_mat)
-print("gen_vehicle: consolidated %d mesh data blocks onto material "
-      "'%s'" % (len(all_mesh_datas), base))
+    if any(glass_face):
+        me.materials.append(glass_mat)
+        for p, g in zip(me.polygons, glass_face):
+            p.material_index = 1 if g else 0
+print("gen_vehicle: consolidated %d mesh data blocks onto materials "
+      "'%s'/'%s-glass'" % (len(all_mesh_datas), base, base))
 
 # --- JSON fragment (Ogre coordinates) ---
 smn, smx = mesh_bbox(root.data)
@@ -664,6 +689,18 @@ bpy.ops.ogre.export(filepath=scene_file,
 IDMAP_MATERIAL_TEMPLATE = """// written by gen_vehicle.py — merged ID-map vehicle material
 // (CAR_MODELING.md).  Not a blender2ogre product; hand edits are
 // overwritten by every export.
+//
+// Three materials per car:
+//   @BASE@              paint/bloom submeshes, fully opaque.
+//   @BASE@-glass        near glass submesh (<10 m): alpha-blended,
+//                       depth_write OFF so it lands in OGRE's
+//                       transparent collection and can never
+//                       depth-block the interior/characters behind it
+//                       (they render first, the glass blends over).
+//   @BASE@-glass-opaque far glass submesh (>=10 m): solid.
+// The demo's SedanGlassLodListener swaps only the -glass submeshes
+// between the near and far variants; paint submeshes always keep
+// @BASE@.
 material @BASE@
 {
 	receive_shadows on
@@ -672,7 +709,42 @@ material @BASE@
 		pass
 		{
 			cull_hardware clockwise
-			depth_write on
+
+			vertex_program_ref VehicleIdMapVP
+			{
+			}
+
+			fragment_program_ref VehicleIdMapFP
+			{
+				param_named glassAlpha float 1.0
+			}
+
+			texture_unit
+			{
+				texture @BASE@-atlas.png
+				tex_address_mode wrap
+				filtering linear linear none
+			}
+
+			texture_unit
+			{
+				texture @BASE@-idmap.png
+				tex_address_mode clamp
+				filtering point point none
+			}
+		}
+	}
+}
+
+material @BASE@-glass
+{
+	receive_shadows on
+	technique
+	{
+		pass
+		{
+			cull_hardware clockwise
+			depth_write off
 			scene_blend alpha_blend
 
 			vertex_program_ref VehicleIdMapVP
@@ -701,7 +773,7 @@ material @BASE@
 	}
 }
 
-material @BASE@-opaque
+material @BASE@-glass-opaque
 {
 	receive_shadows on
 	technique
@@ -742,8 +814,11 @@ with open(mat_path, "w") as f:
     f.write(IDMAP_MATERIAL_TEMPLATE.replace("@BASE@", base))
 print("gen_vehicle: wrote merged material %s" % mat_path)
 
-# Drop the stale split-material files from pre-ID-map exports so the
-# resource dir does not accumulate them.
+# blender2ogre also writes a fixed-function <base>-glass.material for
+# the glass material slot; drop it (and the stale pre-ID-map split
+# files) — the template above defines every <base>* material and a
+# duplicate definition from another script would shadow it depending
+# on resource parse order.
 for suffix in ("-color", "-color-bloom", "-glass"):
     stale = os.path.join(outdir, base + suffix + ".material")
     if os.path.exists(stale):