refactor: extract ResourceId utils, split diff.cpp, replace magic numbers

- Create resource_id.h with shared toResourceId/fromResourceId inline
  functions, eliminating duplicate definitions across 13 source files
- Create constants.h defining kMaxRenderTargets, kDefaultDrawLimit,
  kDefaultShaderSearchLimit, kHistogramBucketCount, kMaxDebugVarComponents
- Split monolithic diff.cpp (1122 lines) into 4 focused modules:
  diff_alignment.cpp, diff_structure.cpp, diff_pipeline.cpp, diff_summary.cpp
  with diff_internal.h for shared helpers

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: JiaboLi-GitHub

CMakeLists.txt

@@ -44,7 +44,10 @@ if(RENDERDOC_DIR)
         src/core/usage.cpp
         src/core/assertions.cpp
         src/core/diff_session.cpp
-        src/core/diff.cpp
+        src/core/diff_alignment.cpp
+        src/core/diff_structure.cpp
+        src/core/diff_pipeline.cpp
+        src/core/diff_summary.cpp
         src/core/pass_analysis.cpp
     )
     target_include_directories(renderdoc-core PUBLIC

src/core/constants.h

@@ -0,0 +1,12 @@
+#pragma once
+#include <cstdint>
+
+namespace renderdoc::core {
+
+constexpr int kMaxRenderTargets = 8;
+constexpr uint32_t kDefaultDrawLimit = 1000;
+constexpr uint32_t kDefaultShaderSearchLimit = 50;
+constexpr uint32_t kHistogramBucketCount = 256;
+constexpr uint32_t kMaxDebugVarComponents = 16;
+
+} // namespace renderdoc::core

src/core/debug.cpp

@@ -1,4 +1,5 @@
 #include "core/debug.h"
+#include "core/constants.h"
 #include "core/errors.h"
 #include <renderdoc_replay.h>
 #include <cstring>
@@ -67,15 +68,15 @@ DebugVariable convertVariable(const ShaderVariable& sv) {
 
     if (isFloatType(sv.type)) {
         dv.floatValues.resize(count);
-        for (uint32_t i = 0; i < count && i < 16; i++)
+        for (uint32_t i = 0; i < count && i < kMaxDebugVarComponents; i++)
             dv.floatValues[i] = sv.value.f32v[i];
     } else if (isSignedIntType(sv.type)) {
         dv.intValues.resize(count);
-        for (uint32_t i = 0; i < count && i < 16; i++)
+        for (uint32_t i = 0; i < count && i < kMaxDebugVarComponents; i++)
             dv.intValues[i] = sv.value.s32v[i];
     } else {
         dv.uintValues.resize(count);
-        for (uint32_t i = 0; i < count && i < 16; i++)
+        for (uint32_t i = 0; i < count && i < kMaxDebugVarComponents; i++)
             dv.uintValues[i] = sv.value.u32v[i];
     }