gpu: add BindGroup.Entry

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

gpu/TODO-webgpu.h

@@ -1,13 +1,3 @@
-typedef struct WGPUBindGroupEntry {
-    WGPUChainedStruct const * nextInChain;
-    uint32_t binding;
-    WGPUBuffer buffer; // nullable
-    uint64_t offset;
-    uint64_t size;
-    WGPUSampler sampler; // nullable
-    WGPUTextureView textureView; // nullable
-} WGPUBindGroupEntry;
-
 typedef struct WGPUBlendComponent {
     WGPUBlendOperation operation;
     WGPUBlendFactor srcFactor;

gpu/src/Buffer.zig

@@ -3,7 +3,6 @@ const std = @import("std");
 pub const Buffer = enum(usize) {
     _,
 
-    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Buffer = @intToEnum(Buffer, 0);
 
     pub const BindingType = enum(u32) {

gpu/src/Sampler.zig

@@ -1,7 +1,6 @@
 pub const Sampler = enum(usize) {
     _,
 
-    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Sampler = @intToEnum(Sampler, 0);
 
     pub const AddressMode = enum(u32) {

gpu/src/bind_group.zig

@@ -1,6 +1,21 @@
+const Buffer = @import("buffer.zig").Buffer;
+const Sampler = @import("sampler.zig").Sampler;
+const TextureView = @import("texture_view.zig").TextureView;
+const ChainedStruct = @import("types.zig").ChainedStruct;
+
 pub const BindGroup = enum(usize) {
     _,
 
     // TODO: verify there is a use case for nullable value of this type.
     pub const none: BindGroup = @intToEnum(BindGroup, 0);
+
+    pub const Entry = extern struct {
+        next_in_chain: *const ChainedStruct,
+        binding: u32,
+        buffer: Buffer = Buffer.none, // nullable
+        offset: u64,
+        size: u64,
+        sampler: Sampler = Sampler.none, // nullable
+        texture_view: TextureView = TextureView.none, // nullable
+    };
 };

gpu/src/texture_view.zig

@@ -1,7 +1,6 @@
 pub const TextureView = enum(usize) {
     _,
 
-    // TODO: verify there is a use case for nullable value of this type.
     pub const none: TextureView = @intToEnum(TextureView, 0);
 
     pub const Dimension = enum(u32) {