gpu: convert TextureView from enum(usize) to *opaque

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

gpu/src/bind_group.zig

@@ -13,7 +13,7 @@ pub const BindGroupEntry = extern struct {
     offset: u64,
     size: u64,
     sampler: ?Sampler,
-    texture_view: TextureView = TextureView.none, // nullable
+    texture_view: ?TextureView,
 };
 
 pub const BindGroupDescriptor = extern struct {

gpu/src/external_texture.zig

@@ -16,7 +16,7 @@ pub const ExternalTextureDescriptor = extern struct {
     next_in_chain: *const ChainedStruct,
     label: ?[*:0]const u8 = null,
     plane0: TextureView,
-    plane1: TextureView = TextureView.none, // nullable
+    plane1: ?TextureView,
     do_yuv_to_rgb_conversion_only: bool,
     yuv_to_rgb_conversion_matrix: ?[*]const f32 = null, // nullable
     src_transform_function_parameters: [*]const f32,

gpu/src/texture.zig

@@ -1,6 +1,7 @@
 const std = @import("std");
 const ChainedStruct = @import("types.zig").ChainedStruct;
 const TextureView = @import("texture_view.zig").TextureView;
+const TextureViewDimension = @import("texture_view.zig").TextureViewDimension;
 const Extent3D = @import("types.zig").Extent3D;
 
 pub const Texture = enum(usize) {
@@ -165,7 +166,7 @@ pub const Texture = enum(usize) {
     pub const BindingLayout = extern struct {
         next_in_chain: *const ChainedStruct,
         sample_type: SampleType,
-        view_dimension: TextureView.Dimension,
+        view_dimension: TextureViewDimension,
         multisampled: bool,
     };
 

gpu/src/texture_view.zig

@@ -1,30 +1,26 @@
 const ChainedStruct = @import("types.zig").ChainedStruct;
 const Texture = @import("texture.zig").Texture;
 
-pub const TextureView = enum(usize) {
-    _,
+pub const TextureView = *opaque {};
 
-    pub const none: TextureView = @intToEnum(TextureView, 0);
-
-    pub const Dimension = enum(u32) {
-        dimension_undef = 0x00000000,
-        dimension_1d = 0x00000001,
-        dimension_2d = 0x00000002,
-        dimension_2d_array = 0x00000003,
-        dimension_cube = 0x00000004,
-        dimension_cube_array = 0x00000005,
-        dimension_3d = 0x00000006,
-    };
-
-    pub const Descriptor = extern struct {
-        next_in_chain: *const ChainedStruct,
-        label: ?[*:0]const u8 = null,
-        format: Texture.Format,
-        dimension: Dimension,
-        base_mip_level: u32,
-        mip_level_count: u32,
-        base_array_layer: u32,
-        array_layer_count: u32,
-        aspect: Texture.Aspect,
-    };
+pub const TextureViewDimension = enum(u32) {
+    dimension_undef = 0x00000000,
+    dimension_1d = 0x00000001,
+    dimension_2d = 0x00000002,
+    dimension_2d_array = 0x00000003,
+    dimension_cube = 0x00000004,
+    dimension_cube_array = 0x00000005,
+    dimension_3d = 0x00000006,
+};
+
+pub const TextureViewDescriptor = extern struct {
+    next_in_chain: *const ChainedStruct,
+    label: ?[*:0]const u8 = null,
+    format: Texture.Format,
+    dimension: TextureViewDimension,
+    base_mip_level: u32,
+    mip_level_count: u32,
+    base_array_layer: u32,
+    array_layer_count: u32,
+    aspect: Texture.Aspect,
 };

gpu/src/types.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 const testing = std.testing;
 const Texture = @import("texture.zig").Texture;
 const TextureView = @import("texture_view.zig").TextureView;
+const TextureViewDimension = @import("texture_view.zig").TextureViewDimension;
 const Buffer = @import("buffer.zig").Buffer;
 const ShaderModule = @import("shader_module.zig").ShaderModule;
 
@@ -502,7 +503,7 @@ pub const StorageTextureBindingLayout = extern struct {
     next_in_chain: *const ChainedStruct,
     access: StorageTextureAccess,
     format: Texture.Format,
-    view_dimension: TextureView.Dimension,
+    view_dimension: TextureViewDimension,
 };
 
 pub const VertexAttribute = extern struct {
@@ -559,8 +560,8 @@ pub const ProgrammableStageDescriptor = extern struct {
 };
 
 pub const RenderPassColorAttachment = extern struct {
-    view: TextureView = TextureView.none, // nullable
-    resolve_target: TextureView = TextureView.none, // nullable
+    view: ?TextureView,
+    resolve_target: ?TextureView,
     load_op: LoadOp,
     store_op: StoreOp,
     clear_color: Color,