Add placeholder fog volume

res/shaders/fog.wgsl

@@ -0,0 +1,46 @@
+#include globals.wgsl
+
+@vertex
+fn vs_main(
+    model: VertexInput,
+    instance: InstanceInput,
+) -> VertexOutput {
+    let model_matrix = mat4x4<f32>(
+        instance.model_matrix_0,
+        instance.model_matrix_1,
+        instance.model_matrix_2,
+        instance.model_matrix_3,
+    );
+    let normal_matrix = mat3x3<f32>(
+        instance.normal_matrix_0,
+        instance.normal_matrix_1,
+        instance.normal_matrix_2,
+    );
+
+    let world_normal = normalize(normal_matrix * model.normal);
+    let world_tangent = normalize(normal_matrix * model.tangent);
+    let world_bitangent = normalize(normal_matrix * model.bitangent);
+    let tangent_matrix = transpose(mat3x3<f32>(
+        world_tangent,
+        world_bitangent,
+        world_normal,
+    ));
+
+    let world_position = model_matrix * vec4<f32>(model.position, 1.0);
+
+    var out: VertexOutput;
+    out.clip_position = camera.proj * camera.view * world_position;
+    out.tex_coords = model.tex_coords;
+    out.tangent_position = tangent_matrix * world_position.xyz;
+    out.tangent_light_position = tangent_matrix * light.position;
+    out.tangent_view_position = tangent_matrix * camera.position.xyz;
+
+    out.world_position = world_position;
+
+    return out;
+}
+
+@fragment
+fn fs_main(vert: VertexOutput) -> @location(0) vec4<f32> {
+    return vec4<f32>(0.5, 0.5, 0.5, 0.1);
+}