refactor(render): unify scene rendering paths

Route model, paper, viewport and nested block content through one traversal while preserving leaf renderers. Carry decoded material state into mesh shading and harden solid geometry conversion.

src/shaders/mesh.wgsl

@@ -37,6 +37,11 @@ struct MaterialMaps {
     present0: vec4<u32>,
     blends1:  vec4<f32>,
     present1: vec4<u32>,
+    tiling0: vec4<u32>,
+    tiling1: vec4<u32>,
+    render_modes: vec4<u32>,
+    source_state: vec4<u32>,
+    indirect: vec4<f32>,
 };
 
 @group(1) @binding(0) var diffuse_map: texture_2d<f32>;
@@ -186,8 +191,20 @@ fn vs_edge(
     return out;
 }
 
+fn map_weight(uv: vec2<f32>, tiling: u32) -> f32 {
+    if (tiling == 2u) {
+        return select(
+            0.0,
+            1.0,
+            all(uv >= vec2<f32>(0.0)) && all(uv <= vec2<f32>(1.0)),
+        );
+    }
+    return 1.0;
+}
+
 @fragment
 fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
+    let two_sided = maps.render_modes.x != 0u;
     var n: vec3<f32>;
     if (u.flat_shade > 0.5) {
         // Per-triangle face normal: derivatives of the interpolated
@@ -197,7 +214,6 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
     } else {
         n = normalize(in.normal);
     }
-
     // Build a derivative tangent frame from the generated material UVs. This
     // works for planar/box/cylindrical/spherical AcDbMaterial projections and
     // does not require ACIS to carry explicit texture-coordinate vertices.
@@ -218,7 +234,9 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
         let mapped = normalize(
             tangent * sampled.x + bitangent * sampled.y + n * sampled.z
         );
-        let strength = maps.blends1.z * max(in.advanced.x, 0.0);
+        let strength = maps.blends1.z
+            * map_weight(in.uv_normal, maps.tiling1.z)
+            * max(in.advanced.x, 0.0);
         n = normalize(mix(n, mapped, clamp(strength, 0.0, 1.0)));
     } else if (maps.present1.x != 0u) {
         let height = dot(
@@ -226,7 +244,12 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
             vec3<f32>(0.2126, 0.7152, 0.0722),
         );
         let slope = tangent * dpdx(height) + bitangent * dpdy(height);
-        n = normalize(n - slope * maps.blends1.x * max(in.advanced.y, 0.0) * 4.0);
+        n = normalize(
+            n - slope
+                * maps.blends1.x
+                * map_weight(in.uv_bump, maps.tiling1.x)
+                * 4.0
+        );
     }
 
     // Native AcDbLight / Sun lighting. When a drawing has no active lights,
@@ -236,9 +259,9 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
     let l1 = normalize(vec3<f32>(-0.7,  0.3,  0.4)); // fill (left)
     let l2 = normalize(vec3<f32>( 0.2, -0.6, -0.8)); // back/under
     var direct_light = vec3<f32>(
-        0.45 * abs(dot(n, l0))
-            + 0.30 * abs(dot(n, l1))
-            + 0.25 * abs(dot(n, l2))
+        0.45 * select(max(dot(n, l0), 0.0), abs(dot(n, l0)), two_sided)
+            + 0.30 * select(max(dot(n, l1), 0.0), abs(dot(n, l1)), two_sided)
+            + 0.25 * select(max(dot(n, l2), 0.0), abs(dot(n, l2)), two_sided)
     );
     var key_light = l0;
     if (u.lighting.x > 0.5) {
@@ -281,9 +304,12 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
                 }
             }
             let strength = max(direction_intensity.w, 0.0) * attenuation;
-            direct_light += color_hotspot.rgb
-                * max(dot(n, light_vector), 0.0)
-                * strength;
+            let response = select(
+                max(dot(n, light_vector), 0.0),
+                abs(dot(n, light_vector)),
+                two_sided,
+            );
+            direct_light += color_hotspot.rgb * response * strength;
             if (index == 0u) {
                 key_light = light_vector;
             }
@@ -298,26 +324,36 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
     );
     let fresnel = fresnel0
         + (1.0 - fresnel0) * pow(1.0 - abs(dot(n, view)), 5.0);
-    let specular_strength = clamp(0.08 + in.material.y + fresnel, 0.0, 1.5);
-    var specular_color = in.specular.rgb;
+    let specular_strength = clamp(1.0 + in.material.y + fresnel, 0.0, 1.5);
+    var albedo = in.color.rgb;
+    if (maps.present0.x != 0u) {
+        let texel = textureSample(diffuse_map, diffuse_sampler, in.uv_diffuse).rgb;
+        let blend = clamp(
+            maps.blends0.x * map_weight(in.uv_diffuse, maps.tiling0.x),
+            0.0,
+            1.0,
+        );
+        albedo = mix(albedo, texel, blend);
+    }
+    var specular_color = select(in.specular.rgb, albedo, in.flags.x == 1u);
     if (maps.present0.y != 0u) {
         let texel = textureSample(specular_map, specular_sampler, in.uv_specular).rgb;
-        specular_color = mix(specular_color, texel, clamp(maps.blends0.y, 0.0, 1.0));
+        let blend = clamp(
+            maps.blends0.y * map_weight(in.uv_specular, maps.tiling0.y),
+            0.0,
+            1.0,
+        );
+        specular_color = mix(specular_color, texel, blend);
     }
     let half_response = select(
-        abs(dot(n, half_vec)),
         max(dot(n, half_vec), 0.0),
-        u.lighting.x > 0.5,
+        abs(dot(n, half_vec)),
+        two_sided,
     );
     let specular = specular_color
         * pow(half_response, gloss_exp)
         * specular_strength
         * max(in.advanced.z, 0.0);
-    var albedo = in.color.rgb;
-    if (maps.present0.x != 0u) {
-        let texel = textureSample(diffuse_map, diffuse_sampler, in.uv_diffuse).rgb;
-        albedo = mix(albedo, texel, clamp(maps.blends0.x, 0.0, 1.0));
-    }
     let ambient_light = albedo * clamp(in.ambient.rgb, vec3<f32>(0.0), vec3<f32>(1.0));
     var lit = ambient_light + albedo * clamp(direct_light, vec3<f32>(0.0), vec3<f32>(2.0)) + specular;
     if (maps.present0.z != 0u) {
@@ -329,7 +365,14 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
         lit = mix(
             lit,
             reflected,
-            clamp(maps.blends0.z * in.material.y * max(in.advanced.z, 0.0), 0.0, 1.0),
+            clamp(
+                maps.blends0.z
+                    * map_weight(in.uv_reflection, maps.tiling0.z)
+                    * in.material.y
+                    * max(in.advanced.z, 0.0),
+                0.0,
+                1.0,
+            ),
         );
     }
     if (maps.present1.y != 0u) {
@@ -341,15 +384,29 @@ fn fs_main(in: VertexOut) -> @location(0) vec4<f32> {
         lit = mix(
             lit,
             transmitted,
-            clamp(maps.blends1.y * in.ambient.a * max(in.advanced.w, 0.0), 0.0, 1.0),
+            clamp(
+                maps.blends1.y
+                    * map_weight(in.uv_refraction, maps.tiling1.y)
+                    * in.ambient.a
+                    * max(in.advanced.w, 0.0),
+                0.0,
+                1.0,
+            ),
         );
     }
-    let emission = clamp(in.material.z + in.material.w, 0.0, 1.0);
-    let rgb = mix(lit, albedo, emission);
+    var rgb = mix(lit, albedo, clamp(in.material.z, 0.0, 1.0));
+    if (in.flags.w == 1u) {
+        rgb = lit + albedo * max(in.material.w, 0.0);
+    }
     var material_alpha = in.color.a;
     if (maps.present0.w != 0u) {
         let opacity = textureSample(opacity_map, opacity_sampler, in.uv_opacity).r;
-        material_alpha *= mix(1.0, opacity, clamp(maps.blends0.w, 0.0, 1.0));
+        let blend = clamp(
+            maps.blends0.w * map_weight(in.uv_opacity, maps.tiling0.w),
+            0.0,
+            1.0,
+        );
+        material_alpha *= mix(1.0, opacity, blend);
     }
     material_alpha *= 1.0 - clamp(in.ambient.a * max(in.advanced.w, 0.0), 0.0, 0.95);
     let alpha = select(1.0, material_alpha, u.transparency_enable > 0.5);