Proposal: Allow use of WGPU_BUFFER_BINDING_LAYOUT_INIT/etc for defaul…

…ting (#450)
webgpu-native · Dec 9, 2024 · 60ea8a6 · 60ea8a6
1 parent 1d18dcc
commit 60ea8a6
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Showing 5 changed files with 54 additions and 26 deletions.
diff --git a/gen/cheader.tmpl b/gen/cheader.tmpl
@@ -76,13 +76,15 @@
 #define _wgpu_COMMA ,
 #if defined(__cplusplus)
 #  define _wgpu_ENUM_ZERO_INIT(type) type(0)
+#  define _wgpu_STRUCT_ZERO_INIT {}
 #  if __cplusplus >= 201103L
 #    define _wgpu_MAKE_INIT_STRUCT(type, value) (type value)
 #  else
 #    define _wgpu_MAKE_INIT_STRUCT(type, value) value
 #  endif
 #else
 #  define _wgpu_ENUM_ZERO_INIT(type) (type)0
+#  define _wgpu_STRUCT_ZERO_INIT {0}
 #  if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
 #    define _wgpu_MAKE_INIT_STRUCT(type, value) ((type) value)
 #  else

diff --git a/gen/gen.go b/gen/gen.go
@@ -581,17 +581,25 @@ func (g *Generator) DefaultValue(member ParameterType, isDocString bool) string
 		} else {
 			return *member.Default
 		}
-	case member.Default != nil:
-		panic(fmt.Errorf("type %s should not have a default", member.Type))
-
-	// Cases that should not have member.Default
 	case strings.HasPrefix(member.Type, "struct."):
 		if member.Optional {
 			return literal("NULL")
-		} else {
+		} else if member.Default == nil {
 			typ := strings.TrimPrefix(member.Type, "struct.")
 			return ref("WGPU_" + ConstantCase(typ) + g.ConstantExtSuffix() + "_INIT")
+		} else if *member.Default == "zero" {
+			if isDocString {
+				return "zero (which sets the entry to `BindingNotUsed`)"
+			} else {
+				return literal("_wgpu_STRUCT_ZERO_INIT")
+			}
+		} else {
+			panic("unknown default for struct type")
 		}
+	case member.Default != nil:
+		panic(fmt.Errorf("type %s should not have a default", member.Type))
+
+	// Cases that should not have member.Default
 	case strings.HasPrefix(member.Type, "callback."):
 		typ := strings.TrimPrefix(member.Type, "callback.")
 		return ref("WGPU_" + ConstantCase(typ) + "_CALLBACK_INFO" + g.ConstantExtSuffix() + "_INIT")

diff --git a/schema.json b/schema.json
@@ -160,7 +160,7 @@
                         "number",
                         "boolean"
                     ],
-                    "description": "Default value assigned to this parameter when using initializer macro"
+                    "description": "Default value assigned to this parameter when using initializer macro. Special context-dependent values include constant names (`constant.*`), bitflag names (unprefixed), and `zero` for struct-zero-init (where zero-init is known to have the desired result)."
                 }
             },
             "required": [

diff --git a/webgpu.h b/webgpu.h
@@ -65,13 +65,15 @@
 #define _wgpu_COMMA ,
 #if defined(__cplusplus)
 #  define _wgpu_ENUM_ZERO_INIT(type) type(0)
+#  define _wgpu_STRUCT_ZERO_INIT {}
 #  if __cplusplus >= 201103L
 #    define _wgpu_MAKE_INIT_STRUCT(type, value) (type value)
 #  else
 #    define _wgpu_MAKE_INIT_STRUCT(type, value) value
 #  endif
 #else
 #  define _wgpu_ENUM_ZERO_INIT(type) (type)0
+#  define _wgpu_STRUCT_ZERO_INIT {0}
 #  if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
 #    define _wgpu_MAKE_INIT_STRUCT(type, value) ((type) value)
 #  else
@@ -1679,7 +1681,7 @@ typedef struct WGPUBufferBindingLayout {
      * If set to @ref WGPUBufferBindingType_Undefined,
      * [defaults](@ref SentinelValues) to @ref WGPUBufferBindingType_Uniform.
      *
-     * The `INIT` macro sets this to @ref WGPUBufferBindingType_BindingNotUsed.
+     * The `INIT` macro sets this to @ref WGPUBufferBindingType_Undefined.
      */
     WGPUBufferBindingType type;
     /**
@@ -1697,7 +1699,7 @@ typedef struct WGPUBufferBindingLayout {
  */
 #define WGPU_BUFFER_BINDING_LAYOUT_INIT _wgpu_MAKE_INIT_STRUCT(WGPUBufferBindingLayout, { \
     /*.nextInChain=*/NULL _wgpu_COMMA \
-    /*.type=*/WGPUBufferBindingType_BindingNotUsed _wgpu_COMMA \
+    /*.type=*/WGPUBufferBindingType_Undefined _wgpu_COMMA \
     /*.hasDynamicOffset=*/0 _wgpu_COMMA \
     /*.minBindingSize=*/0 _wgpu_COMMA \
 })
@@ -2580,7 +2582,7 @@ typedef struct WGPUSamplerBindingLayout {
      * If set to @ref WGPUSamplerBindingType_Undefined,
      * [defaults](@ref SentinelValues) to @ref WGPUSamplerBindingType_Filtering.
      *
-     * The `INIT` macro sets this to @ref WGPUSamplerBindingType_BindingNotUsed.
+     * The `INIT` macro sets this to @ref WGPUSamplerBindingType_Undefined.
      */
     WGPUSamplerBindingType type;
 } WGPUSamplerBindingLayout WGPU_STRUCTURE_ATTRIBUTE;
@@ -2590,7 +2592,7 @@ typedef struct WGPUSamplerBindingLayout {
  */
 #define WGPU_SAMPLER_BINDING_LAYOUT_INIT _wgpu_MAKE_INIT_STRUCT(WGPUSamplerBindingLayout, { \
     /*.nextInChain=*/NULL _wgpu_COMMA \
-    /*.type=*/WGPUSamplerBindingType_BindingNotUsed _wgpu_COMMA \
+    /*.type=*/WGPUSamplerBindingType_Undefined _wgpu_COMMA \
 })
 
 /**
@@ -2807,7 +2809,7 @@ typedef struct WGPUStorageTextureBindingLayout {
      * If set to @ref WGPUStorageTextureAccess_Undefined,
      * [defaults](@ref SentinelValues) to @ref WGPUStorageTextureAccess_WriteOnly.
      *
-     * The `INIT` macro sets this to @ref WGPUStorageTextureAccess_BindingNotUsed.
+     * The `INIT` macro sets this to @ref WGPUStorageTextureAccess_Undefined.
      */
     WGPUStorageTextureAccess access;
     /**
@@ -2828,7 +2830,7 @@ typedef struct WGPUStorageTextureBindingLayout {
  */
 #define WGPU_STORAGE_TEXTURE_BINDING_LAYOUT_INIT _wgpu_MAKE_INIT_STRUCT(WGPUStorageTextureBindingLayout, { \
     /*.nextInChain=*/NULL _wgpu_COMMA \
-    /*.access=*/WGPUStorageTextureAccess_BindingNotUsed _wgpu_COMMA \
+    /*.access=*/WGPUStorageTextureAccess_Undefined _wgpu_COMMA \
     /*.format=*/WGPUTextureFormat_Undefined _wgpu_COMMA \
     /*.viewDimension=*/WGPUTextureViewDimension_Undefined _wgpu_COMMA \
 })
@@ -3304,7 +3306,7 @@ typedef struct WGPUTextureBindingLayout {
      * If set to @ref WGPUTextureSampleType_Undefined,
      * [defaults](@ref SentinelValues) to @ref WGPUTextureSampleType_Float.
      *
-     * The `INIT` macro sets this to @ref WGPUTextureSampleType_BindingNotUsed.
+     * The `INIT` macro sets this to @ref WGPUTextureSampleType_Undefined.
      */
     WGPUTextureSampleType sampleType;
     /**
@@ -3325,7 +3327,7 @@ typedef struct WGPUTextureBindingLayout {
  */
 #define WGPU_TEXTURE_BINDING_LAYOUT_INIT _wgpu_MAKE_INIT_STRUCT(WGPUTextureBindingLayout, { \
     /*.nextInChain=*/NULL _wgpu_COMMA \
-    /*.sampleType=*/WGPUTextureSampleType_BindingNotUsed _wgpu_COMMA \
+    /*.sampleType=*/WGPUTextureSampleType_Undefined _wgpu_COMMA \
     /*.viewDimension=*/WGPUTextureViewDimension_Undefined _wgpu_COMMA \
     /*.multisampled=*/0 _wgpu_COMMA \
 })
@@ -3473,19 +3475,19 @@ typedef struct WGPUBindGroupLayoutEntry {
      */
     WGPUShaderStage visibility;
     /**
-     * The `INIT` macro sets this to @ref WGPU_BUFFER_BINDING_LAYOUT_INIT.
+     * The `INIT` macro sets this to zero (which sets the entry to `BindingNotUsed`).
      */
     WGPUBufferBindingLayout buffer;
     /**
-     * The `INIT` macro sets this to @ref WGPU_SAMPLER_BINDING_LAYOUT_INIT.
+     * The `INIT` macro sets this to zero (which sets the entry to `BindingNotUsed`).
      */
     WGPUSamplerBindingLayout sampler;
     /**
-     * The `INIT` macro sets this to @ref WGPU_TEXTURE_BINDING_LAYOUT_INIT.
+     * The `INIT` macro sets this to zero (which sets the entry to `BindingNotUsed`).
      */
     WGPUTextureBindingLayout texture;
     /**
-     * The `INIT` macro sets this to @ref WGPU_STORAGE_TEXTURE_BINDING_LAYOUT_INIT.
+     * The `INIT` macro sets this to zero (which sets the entry to `BindingNotUsed`).
      */
     WGPUStorageTextureBindingLayout storageTexture;
 } WGPUBindGroupLayoutEntry WGPU_STRUCTURE_ATTRIBUTE;
@@ -3497,10 +3499,10 @@ typedef struct WGPUBindGroupLayoutEntry {
     /*.nextInChain=*/NULL _wgpu_COMMA \
     /*.binding=*/0 _wgpu_COMMA \
     /*.visibility=*/WGPUShaderStage_None _wgpu_COMMA \
-    /*.buffer=*/WGPU_BUFFER_BINDING_LAYOUT_INIT _wgpu_COMMA \
-    /*.sampler=*/WGPU_SAMPLER_BINDING_LAYOUT_INIT _wgpu_COMMA \
-    /*.texture=*/WGPU_TEXTURE_BINDING_LAYOUT_INIT _wgpu_COMMA \
-    /*.storageTexture=*/WGPU_STORAGE_TEXTURE_BINDING_LAYOUT_INIT _wgpu_COMMA \
+    /*.buffer=*/_wgpu_STRUCT_ZERO_INIT _wgpu_COMMA \
+    /*.sampler=*/_wgpu_STRUCT_ZERO_INIT _wgpu_COMMA \
+    /*.texture=*/_wgpu_STRUCT_ZERO_INIT _wgpu_COMMA \
+    /*.storageTexture=*/_wgpu_STRUCT_ZERO_INIT _wgpu_COMMA \
 })
 
 /**

diff --git a/webgpu.yml b/webgpu.yml
@@ -1614,18 +1614,34 @@ structs:
         doc: |
           TODO
         type: struct.buffer_binding_layout
+        # Use struct-zero-init here to get .type=BindingNotUsed (0), instead of
+        # Undefined which is the default in WGPU_BUFFER_BINDING_LAYOUT_INIT.
+        # Zero-init is conveniently correct for the rest of the fields, too.
+        default: zero
       - name: sampler
         doc: |
           TODO
         type: struct.sampler_binding_layout
+        # Use struct-zero-init here to get .type=BindingNotUsed (0), instead of
+        # Undefined which is the default in WGPU_SAMPLER_BINDING_LAYOUT_INIT.
+        # Zero-init is conveniently correct for the rest of the fields, too.
+        default: zero
       - name: texture
         doc: |
           TODO
         type: struct.texture_binding_layout
+        # Use struct-zero-init here to get .sampleType=BindingNotUsed (0), instead of
+        # Undefined which is the default in WGPU_TEXTURE_BINDING_LAYOUT_INIT.
+        # Zero-init is conveniently correct for the rest of the fields, too.
+        default: zero
       - name: storage_texture
         doc: |
           TODO
         type: struct.storage_texture_binding_layout
+        # Use struct-zero-init here to get .access=BindingNotUsed (0), instead of
+        # Undefined which is the default in WGPU_STORAGE_TEXTURE_BINDING_LAYOUT_INIT.
+        # Zero-init is conveniently correct for the rest of the fields, too.
+        default: zero
   - name: blend_component
     doc: |
       TODO
@@ -1672,7 +1688,7 @@ structs:
           If set to @ref WGPUBufferBindingType_Undefined,
           [defaults](@ref SentinelValues) to @ref WGPUBufferBindingType_Uniform.
         type: enum.buffer_binding_type
-        default: binding_not_used
+        default: undefined
       - name: has_dynamic_offset
         doc: |
           TODO
@@ -2577,7 +2593,7 @@ structs:
           If set to @ref WGPUSamplerBindingType_Undefined,
           [defaults](@ref SentinelValues) to @ref WGPUSamplerBindingType_Filtering.
         type: enum.sampler_binding_type
-        default: binding_not_used
+        default: undefined
   - name: sampler_descriptor
     doc: |
       TODO
@@ -2719,7 +2735,7 @@ structs:
           If set to @ref WGPUStorageTextureAccess_Undefined,
           [defaults](@ref SentinelValues) to @ref WGPUStorageTextureAccess_WriteOnly.
         type: enum.storage_texture_access
-        default: binding_not_used
+        default: undefined
       - name: format
         doc: |
           TODO
@@ -2990,7 +3006,7 @@ structs:
           If set to @ref WGPUTextureSampleType_Undefined,
           [defaults](@ref SentinelValues) to @ref WGPUTextureSampleType_Float.
         type: enum.texture_sample_type
-        default: binding_not_used
+        default: undefined
       - name: view_dimension
         doc: |
           If set to @ref WGPUTextureViewDimension_Undefined,