feat(npc): 添加NPC交互高亮效果及复合纹理支持

实现NPC交互时的绿色高亮效果，通过InteractionHighlightSprite类实现
重构NpcAnimation支持复合纹理渲染，优化高亮效果的性能
添加ShaderManager获取所有加载Shader的方法，优化渲染器uniform更新逻辑

Frostbite2D/include/frostbite2D/2d/sprite.h

@@ -49,11 +49,13 @@ public:
   void SetOffset(const Vec2& offset);
   void SetOffset(float x, float y);
 
-private:
+protected:
+  virtual void ConfigureShader(Shader* shader) const;
   void updateTransform();
   Shader* getActiveShader() const;
   Quad createQuad() const;
 
+private:
   Ptr<Texture> texture_;
   std::string shaderName_;
   Color color_ = Color(1.0f, 1.0f, 1.0f, 1.0f);
@@ -68,4 +70,3 @@ private:
 };
 
 }
-

Frostbite2D/include/frostbite2D/graphics/shader_manager.h

@@ -18,6 +18,9 @@ public:
   
   Shader* getShader(const std::string& name);
   bool hasShader(const std::string& name) const;
+  const std::unordered_map<std::string, Ptr<Shader>>& getLoadedShaders() const {
+    return shaders_;
+  }
 
   ~ShaderManager() = default;
 

Frostbite2D/src/frostbite2D/2d/sprite.cpp

@@ -58,39 +58,12 @@ void Sprite::Render() {
   }
 
   Renderer& renderer = Renderer::get();
+  Quad quad = createQuad();
 
-  Vec2 size = GetSize();
+  auto* shader = getActiveShader();
-  if (size.x == 0 || size.y == 0) {
-    size = Vec2((float)texture_->getWidth(), (float)texture_->getHeight());
-  }
-  
-  // 使用完整的变换矩阵进行渲染
-  Rect destRect(0, 0, size.x, size.y);
-  Rect srcRect = srcRect_;
-  if (srcRect.empty()) {
-    srcRect = Rect(0, 0, (float)texture_->getWidth(), (float)texture_->getHeight());
-  }
-  
-  float worldOpacity = GetWorldOpacity();
-  Quad quad = Quad::createTextured(
-    destRect, srcRect, 
-    Vec2((float)texture_->getWidth(), (float)texture_->getHeight()),
-    color_.r, color_.g, color_.b, color_.a * worldOpacity,
-    renderer.shouldShrinkSubTextureUVs()
-  );
-  
-  if (flippedX_) {
-    std::swap(quad.vertices[0].texCoord, quad.vertices[1].texCoord);
-    std::swap(quad.vertices[2].texCoord, quad.vertices[3].texCoord);
-  }
-  if (flippedY_) {
-    std::swap(quad.vertices[0].texCoord, quad.vertices[2].texCoord);
-    std::swap(quad.vertices[1].texCoord, quad.vertices[3].texCoord);
-  }
-  
-  auto* shader = renderer.getShaderManager().getShader("sprite");
   if (shader) {
     shader->use();
+    ConfigureShader(shader);
   }
 
   Transform2D worldTransform = GetWorldTransform();
@@ -154,6 +127,10 @@ void Sprite::SetOffset(float x, float y) {
   offset_.y = y;
 }
 
+void Sprite::ConfigureShader(Shader* shader) const {
+  (void)shader;
+}
+
 void Sprite::updateTransform() {
   Vec2 pos = GetPosition();
   float rotation = GetRotation();

Frostbite2D/src/frostbite2D/graphics/renderer.cpp

@@ -503,27 +503,20 @@ void Renderer::setupBlendMode(BlendMode mode) {
 }
 
 void Renderer::updateUniforms() {
-  if (camera_) {
+  if (!camera_) {
-    auto* spriteShader = shaderManager_.getShader("sprite");
+    return;
-    if (spriteShader) {
-      spriteShader->use();
-      spriteShader->setMat4("u_view", camera_->getViewMatrix());
-      spriteShader->setMat4("u_projection", camera_->getProjectionMatrix());
   }
 
-    auto* coloredShader = shaderManager_.getShader("colored_quad");
+  for (const auto& [name, shaderPtr] : shaderManager_.getLoadedShaders()) {
-    if (coloredShader) {
+    (void)name;
-      coloredShader->use();
+    Shader* shader = shaderPtr.Get();
-      coloredShader->setMat4("u_view", camera_->getViewMatrix());
+    if (!shader) {
-      coloredShader->setMat4("u_projection", camera_->getProjectionMatrix());
+      continue;
     }
 
-    auto* textShader = shaderManager_.getShader("text");
+    shader->use();
-    if (textShader) {
+    shader->setMat4("u_view", camera_->getViewMatrix());
-      textShader->use();
+    shader->setMat4("u_projection", camera_->getProjectionMatrix());
-      textShader->setMat4("u_view", camera_->getViewMatrix());
-      textShader->setMat4("u_projection", camera_->getProjectionMatrix());
-    }
   }
 }
 

Game/include/common/InteractionHighlightSprite.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <frostbite2D/2d/sprite.h>
+
+namespace frostbite2D {
+
+class InteractionHighlightSprite : public Sprite {
+public:
+  InteractionHighlightSprite();
+
+  void SetGroundAnchorInTexture(const Vec2& groundAnchorInTexture);
+
+protected:
+  void ConfigureShader(Shader* shader) const override;
+
+private:
+  Vec2 texelSize_ = Vec2::One();
+};
+
+} // namespace frostbite2D

Game/include/npc/NpcAnimation.h

@@ -2,6 +2,7 @@
 
 #include "npc/NpcDataLoader.h"
 #include <frostbite2D/2d/actor.h>
+#include <frostbite2D/2d/canvas_actor.h>
 #include <frostbite2D/animation/animation.h>
 #include <string>
 
@@ -9,17 +10,47 @@ namespace frostbite2D {
 
 class NpcAnimation : public Actor {
 public:
+  struct CompositeFrameInfo {
+    bool valid = false;
+    Rect localBounds;
+    Vec2 originInTexture = Vec2::Zero();
+    Vec2 groundAnchorInTexture = Vec2::Zero();
+    int width = 1;
+    int height = 1;
+  };
+
   bool Init(const npc::NpcConfig& config);
+  void Update(float deltaTime) override;
+  void Render() override;
   void SetDirection(int direction);
   bool IsReady() const { return displayAnimation_ != nullptr; }
   bool IsAnimationFinished() const;
   const std::string& GetAnimationPath() const { return animationPath_; }
   bool GetDisplayLocalBounds(Rect& outBounds) const;
+  bool EnsureCompositeTextureReady();
+  bool HasCompositeTexture() const;
+  Ptr<Texture> GetCompositeTexture() const;
+  Vec2 GetCompositeTextureSize() const;
+  Vec2 GetCompositeGroundAnchorInTexture() const;
+  uint64 GetCompositeVersion() const { return compositeVersion_; }
 
 private:
+  CompositeFrameInfo ComputeCompositeFrameInfo(int direction) const;
+  CompositeFrameInfo GetCurrentCompositeFrameInfo() const { return compositeFrameInfo_; }
+  uint64 CaptureCurrentRenderSignature() const;
+  void MarkCompositeDirty();
+  void UpdateCompositeCamera();
+  void RefreshCompositeTextureIfNeeded();
+  void RenderCurrentAnimationToCompositeCanvas();
+
   RefPtr<Animation> displayAnimation_ = nullptr;
+  RefPtr<CanvasActor> compositeCanvas_ = nullptr;
+  CompositeFrameInfo compositeFrameInfo_;
   std::string animationPath_;
   int direction_ = 1;
+  bool compositeDirty_ = true;
+  uint64 compositeVersion_ = 0;
+  uint64 lastCompositeSignature_ = 0;
 };
 
 } // namespace frostbite2D

Game/include/npc/NpcObject.h

@@ -1,9 +1,10 @@
 #pragma once
 
 #include "character/CharacterActionTypes.h"
+#include "common/InteractionHighlightSprite.h"
 #include "npc/NpcAnimation.h"
-#include <frostbite2D/2d/text_sprite.h>
 #include <frostbite2D/2d/actor.h>
+#include <frostbite2D/2d/text_sprite.h>
 #include <array>
 #include <optional>
 #include <string>
@@ -21,11 +22,13 @@ public:
   void SetNpcPosition(const Vec2& pos);
   void SetWorldPosition(const CharacterWorldPosition& pos);
   void SetInteractable(bool interactable);
+  void SetInteractionHighlighted(bool highlighted);
   void BeginInteract();
   void EndInteract();
 
   bool CanInteract() const;
   bool IsInteracting() const { return interacting_; }
+  bool IsInteractionHighlighted() const { return interactionHighlighted_; }
   int GetNpcId() const { return npcId_; }
   int GetDirection() const { return direction_; }
   const std::string& GetName() const;
@@ -41,8 +44,10 @@ public:
   void Update(float deltaTime) override;
 
 private:
+  void EnsureInteractionHighlight();
   void EnsureNameLabel();
   void RefreshNameLabel();
+  void SyncInteractionHighlight();
   void SyncActorPositionFromWorld();
 
   int npcId_ = -1;
@@ -50,10 +55,13 @@ private:
   CharacterWorldPosition worldPosition_;
   std::optional<npc::NpcConfig> config_;
   RefPtr<NpcAnimation> animation_ = nullptr;
+  RefPtr<InteractionHighlightSprite> interactionHighlight_ = nullptr;
   std::array<RefPtr<TextSprite>, 8> nameOutlineLabels_;
   RefPtr<TextSprite> nameLabel_ = nullptr;
   bool interactable_ = true;
   bool interacting_ = false;
+  bool interactionHighlighted_ = false;
+  uint64 syncedHighlightCompositeVersion_ = 0;
 };
 
 } // namespace frostbite2D

Game/src/common/InteractionHighlightSprite.cpp

@@ -0,0 +1,35 @@
+#include "common/InteractionHighlightSprite.h"
+
+namespace frostbite2D {
+
+InteractionHighlightSprite::InteractionHighlightSprite() {
+  SetName("interactionHighlight");
+  SetShader("outline_sprite");
+  SetColor(Colors::Green);
+  SetVisible(false);
+}
+
+void InteractionHighlightSprite::SetGroundAnchorInTexture(
+    const Vec2& groundAnchorInTexture) {
+  Vec2 textureSize = GetSize();
+  if (textureSize.x <= 0.0f || textureSize.y <= 0.0f) {
+    SetAnchor(0.5f, 1.0f);
+    texelSize_ = Vec2::One();
+    return;
+  }
+
+  SetAnchor(groundAnchorInTexture.x / textureSize.x,
+            groundAnchorInTexture.y / textureSize.y);
+  texelSize_ = Vec2(1.0f / textureSize.x, 1.0f / textureSize.y);
+}
+
+void InteractionHighlightSprite::ConfigureShader(Shader* shader) const {
+  Sprite::ConfigureShader(shader);
+  if (!shader) {
+    return;
+  }
+
+  shader->setVec2("u_texelSize", texelSize_);
+}
+
+} // namespace frostbite2D

Game/src/npc/NpcAnimation.cpp

@@ -1,13 +1,74 @@
 #include "npc/NpcAnimation.h"
+#include <frostbite2D/graphics/renderer.h>
 #include <SDL2/SDL.h>
+#include <algorithm>
+#include <cmath>
 
 namespace frostbite2D {
+namespace {
+
+constexpr float kCompositePadding = 1.0f;
+
+Rect transformRectBounds(const Rect& rect, const Transform2D& transform) {
+  Vec2 p0 = transform.transformPoint(Vec2(rect.left(), rect.top()));
+  Vec2 p1 = transform.transformPoint(Vec2(rect.right(), rect.top()));
+  Vec2 p2 = transform.transformPoint(Vec2(rect.left(), rect.bottom()));
+  Vec2 p3 = transform.transformPoint(Vec2(rect.right(), rect.bottom()));
+
+  float minX = std::min(std::min(p0.x, p1.x), std::min(p2.x, p3.x));
+  float minY = std::min(std::min(p0.y, p1.y), std::min(p2.y, p3.y));
+  float maxX = std::max(std::max(p0.x, p1.x), std::max(p2.x, p3.x));
+  float maxY = std::max(std::max(p0.y, p1.y), std::max(p2.y, p3.y));
+  return Rect(minX, minY, maxX - minX, maxY - minY);
+}
+
+void combineHash(uint64& seed, uint64 value) {
+  constexpr uint64 kOffset = 0x9e3779b97f4a7c15ULL;
+  seed ^= value + kOffset + (seed << 6) + (seed >> 2);
+}
+
+NpcAnimation::CompositeFrameInfo combineCompositeFrameInfo(
+    const NpcAnimation::CompositeFrameInfo& lhs,
+    const NpcAnimation::CompositeFrameInfo& rhs) {
+  if (!lhs.valid) {
+    return rhs;
+  }
+  if (!rhs.valid) {
+    return lhs;
+  }
+
+  float left = std::floor(std::min(lhs.localBounds.left(), rhs.localBounds.left()));
+  float top = std::floor(std::min(lhs.localBounds.top(), rhs.localBounds.top()));
+  float right = std::ceil(std::max(lhs.localBounds.right(), rhs.localBounds.right()));
+  float bottom =
+      std::ceil(std::max(lhs.localBounds.bottom(), rhs.localBounds.bottom()));
+
+  NpcAnimation::CompositeFrameInfo result;
+  result.valid = true;
+  result.localBounds =
+      Rect(left, top, std::max(right - left, 1.0f), std::max(bottom - top, 1.0f));
+  result.width =
+      std::max(static_cast<int>(std::lround(result.localBounds.width())), 1);
+  result.height =
+      std::max(static_cast<int>(std::lround(result.localBounds.height())), 1);
+  result.originInTexture =
+      Vec2(-result.localBounds.left(), -result.localBounds.top());
+  result.groundAnchorInTexture = result.originInTexture;
+  return result;
+}
+
+} // namespace
 
 bool NpcAnimation::Init(const npc::NpcConfig& config) {
   RemoveAllChildren();
   displayAnimation_ = nullptr;
+  compositeCanvas_ = nullptr;
+  compositeFrameInfo_ = CompositeFrameInfo();
   animationPath_.clear();
   direction_ = 1;
+  compositeDirty_ = true;
+  compositeVersion_ = 0;
+  lastCompositeSignature_ = 0;
 
   if (config.fieldAnimationPath.empty()) {
     SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
@@ -15,6 +76,18 @@ bool NpcAnimation::Init(const npc::NpcConfig& config) {
     return false;
   }
 
+  compositeCanvas_ = MakePtr<CanvasActor>();
+  if (!compositeCanvas_ || !compositeCanvas_->Init(1, 1)) {
+    SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                "NpcAnimation: failed to initialize composite canvas for npc %d",
+                config.id);
+    compositeCanvas_.Reset();
+  } else {
+    compositeCanvas_->SetCustomDrawCallback([this]() {
+      RenderCurrentAnimationToCompositeCanvas();
+    });
+  }
+
   auto animation = MakePtr<Animation>(config.fieldAnimationPath);
   if (!animation || !animation->IsUsable()) {
     SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
@@ -33,14 +106,37 @@ bool NpcAnimation::Init(const npc::NpcConfig& config) {
   SetDirection(1);
   displayAnimation_->Reset();
   SetDirection(direction_);
+
+  CompositeFrameInfo rightInfo = ComputeCompositeFrameInfo(1);
+  CompositeFrameInfo leftInfo = ComputeCompositeFrameInfo(-1);
+  compositeFrameInfo_ = combineCompositeFrameInfo(rightInfo, leftInfo);
+  lastCompositeSignature_ = CaptureCurrentRenderSignature();
   return true;
 }
 
+void NpcAnimation::Update(float deltaTime) {
+  Actor::Update(deltaTime);
+
+  uint64 renderSignature = CaptureCurrentRenderSignature();
+  if (renderSignature != lastCompositeSignature_) {
+    compositeDirty_ = true;
+  }
+}
+
+void NpcAnimation::Render() {
+  if (compositeDirty_ && compositeCanvas_ && Renderer::get().isFrameActive()) {
+    RefreshCompositeTextureIfNeeded();
+  }
+
+  Actor::Render();
+}
+
 void NpcAnimation::SetDirection(int direction) {
   direction_ = direction >= 0 ? 1 : -1;
   if (displayAnimation_) {
     displayAnimation_->SetDirection(direction_);
   }
+  MarkCompositeDirty();
 }
 
 bool NpcAnimation::IsAnimationFinished() const {
@@ -55,4 +151,125 @@ bool NpcAnimation::GetDisplayLocalBounds(Rect& outBounds) const {
   return displayAnimation_->GetStaticLocalBounds(outBounds);
 }
 
+bool NpcAnimation::EnsureCompositeTextureReady() {
+  RefreshCompositeTextureIfNeeded();
+  return HasCompositeTexture();
+}
+
+bool NpcAnimation::HasCompositeTexture() const {
+  return compositeCanvas_ && compositeCanvas_->IsCanvasReady() &&
+         GetCurrentCompositeFrameInfo().valid;
+}
+
+Ptr<Texture> NpcAnimation::GetCompositeTexture() const {
+  return compositeCanvas_ ? compositeCanvas_->GetOutputTexture() : nullptr;
+}
+
+Vec2 NpcAnimation::GetCompositeTextureSize() const {
+  CompositeFrameInfo info = GetCurrentCompositeFrameInfo();
+  return Vec2(static_cast<float>(info.width), static_cast<float>(info.height));
+}
+
+Vec2 NpcAnimation::GetCompositeGroundAnchorInTexture() const {
+  return GetCurrentCompositeFrameInfo().groundAnchorInTexture;
+}
+
+NpcAnimation::CompositeFrameInfo NpcAnimation::ComputeCompositeFrameInfo(
+    int direction) const {
+  CompositeFrameInfo info;
+  if (!displayAnimation_) {
+    return info;
+  }
+
+  Rect animationBounds;
+  if (!displayAnimation_->GetStaticLocalBounds(direction, animationBounds)) {
+    return info;
+  }
+
+  Rect bounds =
+      transformRectBounds(animationBounds, displayAnimation_->GetLocalTransform());
+  if (bounds.empty()) {
+    return info;
+  }
+
+  float left = std::floor(bounds.left() - kCompositePadding);
+  float top = std::floor(bounds.top() - kCompositePadding);
+  float right = std::ceil(bounds.right() + kCompositePadding);
+  float bottom = std::ceil(bounds.bottom() + kCompositePadding);
+
+  info.valid = true;
+  info.localBounds = Rect(left, top, std::max(right - left, 1.0f),
+                          std::max(bottom - top, 1.0f));
+  info.width = std::max(static_cast<int>(std::lround(info.localBounds.width())), 1);
+  info.height = std::max(static_cast<int>(std::lround(info.localBounds.height())), 1);
+  info.originInTexture = Vec2(-info.localBounds.left(), -info.localBounds.top());
+  info.groundAnchorInTexture = info.originInTexture;
+  return info;
+}
+
+uint64 NpcAnimation::CaptureCurrentRenderSignature() const {
+  uint64 signature = 1469598103934665603ULL;
+  combineHash(signature, static_cast<uint64>(direction_ >= 0 ? 1 : 0));
+  if (displayAnimation_) {
+    combineHash(signature, displayAnimation_->GetRenderSignature());
+  }
+  return signature;
+}
+
+void NpcAnimation::MarkCompositeDirty() {
+  compositeDirty_ = true;
+  if (compositeCanvas_) {
+    compositeCanvas_->SetDirty();
+  }
+}
+
+void NpcAnimation::UpdateCompositeCamera() {
+  if (!compositeCanvas_) {
+    return;
+  }
+
+  CompositeFrameInfo info = GetCurrentCompositeFrameInfo();
+  Camera& camera = compositeCanvas_->GetCanvasCamera();
+  camera.setViewport(std::max(info.width, 1), std::max(info.height, 1));
+  camera.setZoom(1.0f);
+  Vec2 cameraOrigin = GetWorldTransform().transformPoint(
+      Vec2(info.localBounds.left(), info.localBounds.top()));
+  camera.setPosition(cameraOrigin);
+}
+
+void NpcAnimation::RefreshCompositeTextureIfNeeded() {
+  if (!compositeDirty_ || !compositeCanvas_) {
+    return;
+  }
+
+  CompositeFrameInfo info = GetCurrentCompositeFrameInfo();
+  if (!info.valid) {
+    compositeDirty_ = false;
+    lastCompositeSignature_ = CaptureCurrentRenderSignature();
+    return;
+  }
+
+  if (!compositeCanvas_->SetCanvasSize(std::max(info.width, 1),
+                                       std::max(info.height, 1))) {
+    return;
+  }
+
+  UpdateCompositeCamera();
+  if (!compositeCanvas_->Redraw()) {
+    return;
+  }
+
+  compositeDirty_ = false;
+  lastCompositeSignature_ = CaptureCurrentRenderSignature();
+  ++compositeVersion_;
+}
+
+void NpcAnimation::RenderCurrentAnimationToCompositeCanvas() {
+  if (!displayAnimation_) {
+    return;
+  }
+
+  RenderChildren();
+}
+
 } // namespace frostbite2D

Game/src/npc/NpcObject.cpp

@@ -42,10 +42,13 @@ bool NpcObject::Construction(int npcId) {
   worldPosition_ = CharacterWorldPosition();
   config_.reset();
   animation_ = nullptr;
+  interactionHighlight_ = nullptr;
   nameOutlineLabels_.fill(nullptr);
   nameLabel_ = nullptr;
   interactable_ = true;
   interacting_ = false;
+  interactionHighlighted_ = false;
+  syncedHighlightCompositeVersion_ = 0;
 
   auto config = npc::loadNpcConfig(npcId);
   if (!config) {
@@ -68,11 +71,13 @@ bool NpcObject::Construction(int npcId) {
   config_ = *config;
   npcId_ = npcId;
   animation_ = animation;
+  EnsureInteractionHighlight();
   AddChild(animation_);
   EnsureNameLabel();
 
   SetWorldPosition({});
   SetDirection(1);
+  SetInteractionHighlighted(false);
   RefreshNameLabel();
   SDL_Log("NpcObject: npc %d construction complete", npcId_);
   return true;
@@ -84,6 +89,7 @@ void NpcObject::SetDirection(int direction) {
     animation_->SetDirection(direction_);
   }
   RefreshNameLabel();
+  SyncInteractionHighlight();
 }
 
 void NpcObject::SetNpcPosition(const Vec2& pos) {
@@ -108,6 +114,19 @@ void NpcObject::SetInteractable(bool interactable) {
   }
 }
 
+void NpcObject::SetInteractionHighlighted(bool highlighted) {
+  if (interactionHighlighted_ == highlighted) {
+    SyncInteractionHighlight();
+    return;
+  }
+
+  interactionHighlighted_ = highlighted;
+  if (!interactionHighlighted_) {
+    syncedHighlightCompositeVersion_ = 0;
+  }
+  SyncInteractionHighlight();
+}
+
 void NpcObject::BeginInteract() {
   if (CanInteract()) {
     interacting_ = true;
@@ -144,6 +163,19 @@ bool NpcObject::IsAnimationFinished() const {
 
 void NpcObject::Update(float deltaTime) {
   Actor::Update(deltaTime);
+  SyncInteractionHighlight();
+}
+
+void NpcObject::EnsureInteractionHighlight() {
+  if (interactionHighlight_) {
+    return;
+  }
+
+  interactionHighlight_ = MakePtr<InteractionHighlightSprite>();
+  interactionHighlight_->SetZOrder(-1);
+  interactionHighlight_->SetPosition(0.0f, 0.0f);
+  interactionHighlight_->SetVisible(false);
+  AddChild(interactionHighlight_);
 }
 
 void NpcObject::EnsureNameLabel() {
@@ -206,6 +238,38 @@ void NpcObject::RefreshNameLabel() {
   }
 }
 
+void NpcObject::SyncInteractionHighlight() {
+  if (!interactionHighlight_) {
+    return;
+  }
+
+  if (!interactionHighlighted_ || !animation_ ||
+      !animation_->EnsureCompositeTextureReady() ||
+      !animation_->HasCompositeTexture()) {
+    interactionHighlight_->SetVisible(false);
+    return;
+  }
+
+  uint64 compositeVersion = animation_->GetCompositeVersion();
+  if (syncedHighlightCompositeVersion_ != compositeVersion) {
+    Ptr<Texture> compositeTexture = animation_->GetCompositeTexture();
+    Vec2 compositeSize = animation_->GetCompositeTextureSize();
+    if (!compositeTexture || compositeSize.x <= 0.0f || compositeSize.y <= 0.0f) {
+      interactionHighlight_->SetVisible(false);
+      return;
+    }
+
+    interactionHighlight_->SetTexture(compositeTexture);
+    interactionHighlight_->SetSize(compositeSize);
+    interactionHighlight_->SetGroundAnchorInTexture(
+        animation_->GetCompositeGroundAnchorInTexture());
+    interactionHighlight_->SetPosition(0.0f, 0.0f);
+    syncedHighlightCompositeVersion_ = compositeVersion;
+  }
+
+  interactionHighlight_->SetVisible(true);
+}
+
 void NpcObject::SyncActorPositionFromWorld() {
   SetPosition(worldPosition_.ToScreenPosition());
   SetZOrder(worldPosition_.y);

Game/src/scene/GameMapTestScene.cpp

@@ -11,6 +11,7 @@ constexpr char kTestMapPath[] = "map/elvengard/d_elvengard.map";
 constexpr int kTestNpcId = 2;
 constexpr float kTestNpcOffsetX = 180.0f;
 constexpr float kTestNpcOffsetY = -24.0f;
+constexpr float kNpcInteractionHighlightRadius = 40.0f;
 
 } // namespace
 
@@ -111,6 +112,18 @@ void GameMapTestScene::onExit() {
 
 void GameMapTestScene::Update(float deltaTime) {
   Scene::Update(deltaTime);
+
+  if (npc_) {
+    bool shouldHighlight = false;
+    if (character_) {
+      shouldHighlight =
+          character_->GetWorldPosition().ToGroundPosition().distance(
+              npc_->GetWorldPosition().ToGroundPosition()) <=
+          kNpcInteractionHighlightRadius;
+    }
+    npc_->SetInteractionHighlighted(shouldHighlight);
+  }
+
   cameraController_.Update(deltaTime);
 }