syntax = "proto3";
 
package shading;
 
import "google/protobuf/any.proto";
 
// -------------------------------------------------
// Semantic versioning message
// -------------------------------------------------
message Version {
  uint32 major = 1;
  uint32 minor = 2;
  uint32 patch = 3;
}
 
// -------------------------------------------------
// Version 1 of ShaderInput
// -------------------------------------------------
message ShaderInputV1 {
  Version schema_version = 1; // semantic version of this message
 
  optional string name = 2;
  string type = 3;
  string default_value = 4;
 
  repeated string connections = 5;
 
  oneof value {
float float_value = 6;
repeated float color3_value = 7;
  }
 
  google.protobuf.Any metadata = 8;
 
  // Reserved fields from v1 (to prevent reuse)
  reserved 9, 10;
  reserved "deprecated_field_name";
}
 
// -------------------------------------------------
// Version 2 of ShaderInput (evolved)
// -------------------------------------------------
message ShaderInputV2 {
  Version schema_version = 1; // still semantic versioned (e.g., 2.0.0)
 
  optional string name = 2;
  string type = 3;
  string default_value = 4;
 
  repeated string connections = 5;
 
  // Oneof extended to include int value
  oneof value {
float float_value = 6;
repeated float color3_value = 7;
int32 int_value = 11; // new field
  }
 
  // Optional new description field
  optional string description = 12;
 
  google.protobuf.Any metadata = 8;
 
  // Reserved fields carry over
  reserved 9, 10;
  reserved "deprecated_field_name";
}
 
// -------------------------------------------------
// Container for multiple shader inputs (nodes)
// -------------------------------------------------
message ShaderNode {
  string name = 1;
 
  Version schema_version = 2; // version of the node definition
 
  repeated ShaderInputV2 inputs = 3;
 
  google.protobuf.Any extensions = 4;
}

Feature	Example	Purpose
`Version`	`Version schema_version`	Semantic versioning of message schema (major.minor.patch)
`optional`	`optional string name = 2;`	Field may be omitted, safe for forward/backward compatibility
`repeated`	`repeated string connections = 5;`	Supports multiple inputs or multi-connections
`oneof`	`oneof value { ... }`	Only one of these fields may be set at a time; new values can be added safely in later versions
`reserved`	`reserved 9,10; reserved "deprecated_field_name";`	Prevents reuse of field numbers or names from older versions, preserving compatibility
`Any`	`google.protobuf.Any metadata = 8;`	Embeds arbitrary messages; allows future extensions without changing the core schema
Schema evolution	`ShaderInputV1 → ShaderInputV2`	Added `description` and `int_value` fields without breaking backward compatibility

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