gpu: add BindGroupLayout.Entry

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

gpu/TODO-webgpu.h

@@ -1,13 +1,3 @@
-pub const WGPUBindGroupLayoutEntry = extern struct {
-    next_in_chain: *const ChainedStruct,
-    binding: u32,
-    visibility: ShaderStageFlags,
-    buffer: BufferBindingLayout,
-    sampler: SamplerBindingLayout,
-    texture: TextureBindingLayout,
-    storage_texture: StorageTextureBindingLayout,
-};
-
 pub const BlendState = extern struct {
     color: BlendComponent,
     alpha: BlendComponent,

gpu/src/bind_group_layout.zig

@@ -1,6 +1,23 @@
+const ChainedStruct = @import("types.zig").ChainedStruct;
+const ShaderStageFlags = @import("types.zig").ShaderStageFlags;
+const Buffer = @import("buffer.zig").Buffer;
+const Sampler = @import("sampler.zig").Sampler;
+const Texture = @import("texture.zig").Texture;
+const StorageTextureBindingLayout = @import("types.zig").StorageTextureBindingLayout;
+
 pub const BindGroupLayout = enum(usize) {
     _,
 
     // TODO: verify there is a use case for nullable value of this type.
     pub const none: BindGroupLayout = @intToEnum(BindGroupLayout, 0);
+
+    pub const Entry = extern struct {
+        next_in_chain: *const ChainedStruct,
+        binding: u32,
+        visibility: ShaderStageFlags,
+        buffer: Buffer.BindingLayout,
+        sampler: Sampler.BindingLayout,
+        texture: Texture.BindingLayout,
+        storage_texture: StorageTextureBindingLayout,
+    };
 };

gpu/src/types.zig

@@ -345,7 +345,7 @@ pub const MapMode = packed struct {
     }
 };
 
-pub const ShaderStage = packed struct {
+pub const ShaderStageFlags = packed struct {
     vertex: bool = false,
     fragment: bool = false,
     compute: bool = false,
@@ -359,9 +359,9 @@ pub const ShaderStage = packed struct {
         );
     }
 
-    pub const none = ShaderStage{};
+    pub const none = ShaderStageFlags{};
 
-    pub fn equal(a: ShaderStage, b: ShaderStage) bool {
+    pub fn equal(a: ShaderStageFlags, b: ShaderStageFlags) bool {
         return @truncate(u3, @bitCast(u32, a)) == @truncate(u3, @bitCast(u32, b));
     }
 };