allow overlay texture

src/webview/mesh/webview_extend_standard_material.wgsl

@@ -11,6 +11,7 @@
 }
 #import webview::util::{
     surface_color,
+    overlay_color,
 }
 
 @fragment
@@ -21,11 +22,18 @@ fn fragment(
     var out: FragmentOutput;
     var pbr_input = pbr_input_from_standard_material(in, is_front);
     
-    var alpha = pbr_input.material.base_color.a;
-    pbr_input.material.base_color *= surface_color(in.uv);
-    // pbr_input.material.base_color = alpha_discard(pbr_input.material, pbr_input.material.base_color);
+    // var alpha = pbr_input.material.base_color.a;
     
-    out.color = pbr_input.material.base_color * alpha;
+    if overlay_color(in.uv).a > 0.0 {
+        pbr_input.material.base_color *= surface_color(in.uv);
+        pbr_input.material.base_color *= overlay_color(in.uv);
+    } else {
+        pbr_input.material.base_color *= surface_color(in.uv);
+    }
+    
+    pbr_input.material.base_color = alpha_discard(pbr_input.material, pbr_input.material.base_color);
+    
+    out.color = pbr_input.material.base_color;
     // out.color.a *= alpha;
 
     return out;

src/webview/mesh/webview_material.rs

@@ -30,6 +30,9 @@ pub struct WebviewMaterial {
     #[texture(101)]
     #[sampler(102)]
     pub surface: Option<Handle<Image>>,
+    #[texture(103)]
+    #[sampler(104)]
+    pub overlay: Option<Handle<Image>>,
 }
 
 impl Material for WebviewMaterial {}

src/webview/mesh/webview_util.wgsl

@@ -8,7 +8,13 @@
 @group(#{MATERIAL_BIND_GROUP}) @binding(101) var surface_texture: texture_2d<f32>;
 @group(#{MATERIAL_BIND_GROUP}) @binding(102) var surface_sampler: sampler;
 
+@group(#{MATERIAL_BIND_GROUP}) @binding(103) var overlay_texture: texture_2d<f32>;
+@group(#{MATERIAL_BIND_GROUP}) @binding(104) var overlay_sampler: sampler;
+
 fn surface_color(uv: vec2<f32>) -> vec4<f32> {
-    // let flip = vec2(1.0 - uv.x, uv.y);
     return textureSampleBias(surface_texture, surface_sampler, uv, view.mip_bias);
 }
+
+fn overlay_color(uv: vec2<f32>) -> vec4<f32> {
+    return textureSampleBias(overlay_texture, overlay_sampler, uv, view.mip_bias);
+}