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

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

gpu/src/bind_group.zig

@@ -9,7 +9,7 @@ pub const BindGroup = *opaque {};
 pub const BindGroupEntry = extern struct {
     next_in_chain: *const ChainedStruct,
     binding: u32,
-    buffer: Buffer = Buffer.none, // nullable
+    buffer: ?Buffer,
     offset: u64,
     size: u64,
     sampler: Sampler = Sampler.none, // nullable

gpu/src/bind_group_layout.zig

@@ -1,6 +1,7 @@
 const ChainedStruct = @import("types.zig").ChainedStruct;
 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 Texture = @import("texture.zig").Texture;
 const StorageTextureBindingLayout = @import("types.zig").StorageTextureBindingLayout;
@@ -11,7 +12,7 @@ pub const BindGroupLayoutEntry = extern struct {
     next_in_chain: *const ChainedStruct,
     binding: u32,
     visibility: ShaderStageFlags,
-    buffer: Buffer.BindingLayout,
+    buffer: BufferBindingLayout,
     sampler: Sampler.BindingLayout,
     texture: Texture.BindingLayout,
     storage_texture: StorageTextureBindingLayout,

gpu/src/buffer.zig

@@ -1,67 +1,63 @@
 const std = @import("std");
 const ChainedStruct = @import("types.zig").ChainedStruct;
 
-pub const Buffer = enum(usize) {
-    _,
+pub const Buffer = *opaque {};
 
-    pub const none: Buffer = @intToEnum(Buffer, 0);
-
-    pub const BindingType = enum(u32) {
-        undef = 0x00000000,
-        uniform = 0x00000001,
-        storage = 0x00000002,
-        read_only_storage = 0x00000003,
-    };
-
-    pub const MapAsyncStatus = enum(u32) {
-        success = 0x00000000,
-        err = 0x00000001,
-        unknown = 0x00000002,
-        device_lost = 0x00000003,
-        destroyed_before_callback = 0x00000004,
-        unmapped_before_callback = 0x00000005,
-    };
-
-    pub const Usage = packed struct {
-        map_read: bool = false,
-        map_write: bool = false,
-        copy_src: bool = false,
-        copy_dst: bool = false,
-        index: bool = false,
-        vertex: bool = false,
-        uniform: bool = false,
-        storage: bool = false,
-        indirect: bool = false,
-        query_resolve: bool = false,
-
-        _padding: u22 = 0,
-
-        comptime {
-            std.debug.assert(
-                @sizeOf(@This()) == @sizeOf(u32) and
-                    @bitSizeOf(@This()) == @bitSizeOf(u32),
-            );
-        }
-
-        pub const none = Usage{};
-
-        pub fn equal(a: Usage, b: Usage) bool {
-            return @truncate(u10, @bitCast(u32, a)) == @truncate(u10, @bitCast(u32, b));
-        }
-    };
-
-    pub const BindingLayout = extern struct {
-        next_in_chain: *const ChainedStruct,
-        type: BindingType,
-        has_dynamic_offset: bool = false,
-        min_binding_size: u64 = 0,
-    };
-
-    pub const Descriptor = extern struct {
-        next_in_chain: *const ChainedStruct,
-        label: ?[*:0]const u8 = null,
-        usage: Usage,
-        size: u64,
-        mapped_at_creation: bool,
-    };
+pub const BufferBindingType = enum(u32) {
+    undef = 0x00000000,
+    uniform = 0x00000001,
+    storage = 0x00000002,
+    read_only_storage = 0x00000003,
+};
+
+pub const BufferMapAsyncStatus = enum(u32) {
+    success = 0x00000000,
+    err = 0x00000001,
+    unknown = 0x00000002,
+    device_lost = 0x00000003,
+    destroyed_before_callback = 0x00000004,
+    unmapped_before_callback = 0x00000005,
+};
+
+pub const BufferUsage = packed struct {
+    map_read: bool = false,
+    map_write: bool = false,
+    copy_src: bool = false,
+    copy_dst: bool = false,
+    index: bool = false,
+    vertex: bool = false,
+    uniform: bool = false,
+    storage: bool = false,
+    indirect: bool = false,
+    query_resolve: bool = false,
+
+    _padding: u22 = 0,
+
+    comptime {
+        std.debug.assert(
+            @sizeOf(@This()) == @sizeOf(u32) and
+                @bitSizeOf(@This()) == @bitSizeOf(u32),
+        );
+    }
+
+    pub const none = BufferUsage{};
+
+    pub fn equal(a: BufferUsage, b: BufferUsage) bool {
+        return @truncate(u10, @bitCast(u32, a)) == @truncate(u10, @bitCast(u32, b));
+    }
+};
+
+pub const BufferBindingLayout = extern struct {
+    next_in_chain: *const ChainedStruct,
+    type: BufferBindingType,
+    has_dynamic_offset: bool = false,
+    min_binding_size: u64 = 0,
+};
+
+pub const BufferDescriptor = extern struct {
+    next_in_chain: *const ChainedStruct,
+    label: ?[*:0]const u8 = null,
+    usage: BufferUsage,
+    size: u64,
+    mapped_at_creation: bool,
 };