feat(renderer): add ORM and emissive texture map support to PBR pipeline

- Extended bind group 1: albedo + normal + ORM + emissive (8 bindings)
- pbr_shader.wgsl: ORM sampling (R=AO, G=roughness, B=metallic) + emissive
- deferred_gbuffer.wgsl: ORM + emissive luminance in material_data.w
- deferred_lighting.wgsl: emissive contribution from G-Buffer
- All 5 PBR examples updated with default ORM/emissive textures
- Backward compatible: old 4-binding layout preserved

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

examples/deferred_demo/src/main.rs

@@ -16,7 +16,7 @@ use voltex_renderer::{
     gbuffer_camera_bind_group_layout,
     lighting_gbuffer_bind_group_layout, lighting_lights_bind_group_layout,
     lighting_shadow_bind_group_layout,
-    pbr_texture_bind_group_layout, create_pbr_texture_bind_group,
+    pbr_full_texture_bind_group_layout, create_pbr_full_texture_bind_group,
     SsgiResources, SsgiUniform,
     ssgi_gbuffer_bind_group_layout, ssgi_data_bind_group_layout, create_ssgi_pipeline,
     RtAccel, RtInstance, BlasMeshData, RtShadowResources, RtShadowUniform,
@@ -119,6 +119,8 @@ struct AppState {
     // Keep textures alive
     _albedo_tex: GpuTexture,
     _normal_tex: (wgpu::Texture, wgpu::TextureView, wgpu::Sampler),
+    _orm_tex: GpuTexture,
+    _emissive_tex: GpuTexture,
     _shadow_map: ShadowMap,
     _ibl: IblResources,
     _shadow_uniform_buffer: wgpu::Buffer,
@@ -171,7 +173,7 @@ impl ApplicationHandler for DeferredDemoApp {
         // G-Buffer pass bind group layouts
         // ---------------------------------------------------------------
         let gbuf_cam_layout = gbuffer_camera_bind_group_layout(&gpu.device);
-        let pbr_tex_layout = pbr_texture_bind_group_layout(&gpu.device);
+        let pbr_tex_layout = pbr_full_texture_bind_group_layout(&gpu.device);
         let mat_layout = MaterialUniform::bind_group_layout(&gpu.device);
 
         // Camera dynamic uniform buffer (one CameraUniform per sphere)
@@ -204,17 +206,23 @@ impl ApplicationHandler for DeferredDemoApp {
             }],
         });
 
-        // PBR textures: white albedo + flat normal
+        // PBR textures: white albedo + flat normal + ORM + emissive
         let old_tex_layout = GpuTexture::bind_group_layout(&gpu.device);
         let albedo_tex = GpuTexture::white_1x1(&gpu.device, &gpu.queue, &old_tex_layout);
         let normal_tex = GpuTexture::flat_normal_1x1(&gpu.device, &gpu.queue);
-        let pbr_texture_bind_group = create_pbr_texture_bind_group(
+        let orm_tex = GpuTexture::white_1x1(&gpu.device, &gpu.queue, &old_tex_layout);
+        let emissive_tex = GpuTexture::black_1x1(&gpu.device, &gpu.queue, &old_tex_layout);
+        let pbr_texture_bind_group = create_pbr_full_texture_bind_group(
             &gpu.device,
             &pbr_tex_layout,
             &albedo_tex.view,
             &albedo_tex.sampler,
             &normal_tex.1,
             &normal_tex.2,
+            &orm_tex.view,
+            &orm_tex.sampler,
+            &emissive_tex.view,
+            &emissive_tex.sampler,
         );
 
         // Material bind group (dynamic offset, group 2)
@@ -581,6 +589,8 @@ impl ApplicationHandler for DeferredDemoApp {
             shadow_layout,
             _albedo_tex: albedo_tex,
             _normal_tex: normal_tex,
+            _orm_tex: orm_tex,
+            _emissive_tex: emissive_tex,
             _shadow_map: shadow_map,
             _ibl: ibl,
             _shadow_uniform_buffer: shadow_uniform_buffer,