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

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

gpu/src/bind_group.zig

@@ -12,7 +12,7 @@ pub const BindGroupEntry = extern struct {
     buffer: ?Buffer,
     offset: u64,
     size: u64,
-    sampler: Sampler = Sampler.none, // nullable
+    sampler: ?Sampler,
     texture_view: TextureView = TextureView.none, // nullable
 };
 

gpu/src/bind_group_layout.zig

@@ -3,6 +3,7 @@ const ShaderStageFlags = @import("types.zig").ShaderStageFlags;
 const Buffer = @import("buffer.zig").Buffer;
 const BufferBindingLayout = @import("buffer.zig").BufferBindingLayout;
 const Sampler = @import("sampler.zig").Sampler;
+const SamplerBindingLayout = @import("sampler.zig").SamplerBindingLayout;
 const Texture = @import("texture.zig").Texture;
 const StorageTextureBindingLayout = @import("types.zig").StorageTextureBindingLayout;
 
@@ -13,7 +14,7 @@ pub const BindGroupLayoutEntry = extern struct {
     binding: u32,
     visibility: ShaderStageFlags,
     buffer: BufferBindingLayout,
-    sampler: Sampler.BindingLayout,
+    sampler: SamplerBindingLayout,
     texture: Texture.BindingLayout,
     storage_texture: StorageTextureBindingLayout,
 };

gpu/src/sampler.zig

@@ -2,41 +2,37 @@ const ChainedStruct = @import("types.zig").ChainedStruct;
 const FilterMode = @import("types.zig").FilterMode;
 const CompareFunction = @import("types.zig").CompareFunction;
 
-pub const Sampler = enum(usize) {
-    _,
+pub const Sampler = *opaque {};
 
-    pub const none: Sampler = @intToEnum(Sampler, 0);
-
-    pub const AddressMode = enum(u32) {
-        repeat = 0x00000000,
-        mirror_repeat = 0x00000001,
-        clamp_to_edge = 0x00000002,
-    };
-
-    pub const BindingType = enum(u32) {
-        undef = 0x00000000,
-        filtering = 0x00000001,
-        non_filtering = 0x00000002,
-        comparison = 0x00000003,
-    };
-
-    pub const BindingLayout = extern struct {
-        next_in_chain: *const ChainedStruct,
-        type: BindingType,
-    };
-
-    pub const Descriptor = extern struct {
-        next_in_chain: *const ChainedStruct,
-        label: ?[*:0]const u8 = null,
-        address_mode_u: AddressMode,
-        address_mode_v: AddressMode,
-        address_mode_w: AddressMode,
-        mag_filter: FilterMode,
-        min_filter: FilterMode,
-        mipmap_filter: FilterMode,
-        lod_min_clamp: f32,
-        lod_max_clamp: f32,
-        compare: CompareFunction,
-        max_anisotropy: u16,
-    };
+pub const SamplerAddressMode = enum(u32) {
+    repeat = 0x00000000,
+    mirror_repeat = 0x00000001,
+    clamp_to_edge = 0x00000002,
+};
+
+pub const SamplerBindingType = enum(u32) {
+    undef = 0x00000000,
+    filtering = 0x00000001,
+    non_filtering = 0x00000002,
+    comparison = 0x00000003,
+};
+
+pub const SamplerBindingLayout = extern struct {
+    next_in_chain: *const ChainedStruct,
+    type: SamplerBindingType,
+};
+
+pub const SamplerDescriptor = extern struct {
+    next_in_chain: *const ChainedStruct,
+    label: ?[*:0]const u8 = null,
+    address_mode_u: SamplerAddressMode,
+    address_mode_v: SamplerAddressMode,
+    address_mode_w: SamplerAddressMode,
+    mag_filter: FilterMode,
+    min_filter: FilterMode,
+    mipmap_filter: FilterMode,
+    lod_min_clamp: f32,
+    lod_max_clamp: f32,
+    compare: CompareFunction,
+    max_anisotropy: u16,
 };