refactor: Generic sampler system for composites

Replace hardcoded linear_sampler_ with configurable sampler map.
- SamplerType enum (LinearClamp, LinearRepeat, NearestClamp, NearestRepeat)
- get_or_create_sampler() for lazy sampler creation
- Default to LinearClamp for backward compatibility

Eliminates hardcoded assumptions, more flexible for future use cases.

2 files changed, 71 insertions, 24 deletions

diff --git a/src/gpu/texture_manager.cc b/src/gpu/texture_manager.cc
index 7aeb67a..dfa6315 100644
--- a/src/gpu/texture_manager.cc
+++ b/src/gpu/texture_manager.cc
@@ -21,20 +21,6 @@
 void TextureManager::init(WGPUDevice device, WGPUQueue queue) {
   device_ = device;
   queue_ = queue;
-
-#if !defined(STRIP_GPU_COMPOSITE)
-  // Create linear sampler for composite shaders
-  WGPUSamplerDescriptor sampler_desc = {};
-  sampler_desc.addressModeU = WGPUAddressMode_ClampToEdge;
-  sampler_desc.addressModeV = WGPUAddressMode_ClampToEdge;
-  sampler_desc.magFilter = WGPUFilterMode_Linear;
-  sampler_desc.minFilter = WGPUFilterMode_Linear;
-  sampler_desc.mipmapFilter = WGPUMipmapFilterMode_Linear;
-  sampler_desc.lodMinClamp = 0.0f;
-  sampler_desc.lodMaxClamp = 1.0f;
-  sampler_desc.maxAnisotropy = 1;
-  linear_sampler_ = wgpuDeviceCreateSampler(device_, &sampler_desc);
-#endif
 }
 
 void TextureManager::shutdown() {
@@ -52,10 +38,12 @@ void TextureManager::shutdown() {
   compute_pipelines_.clear();
 
 #if !defined(STRIP_GPU_COMPOSITE)
-  if (linear_sampler_) {
-    wgpuSamplerRelease(linear_sampler_);
-    linear_sampler_ = nullptr;
+  for (auto& pair : samplers_) {
+    if (pair.second) {
+      wgpuSamplerRelease(pair.second);
+    }
   }
+  samplers_.clear();
 #endif
 }
 
@@ -469,10 +457,58 @@ void TextureManager::create_gpu_grid_texture(
 }
 
 #if !defined(STRIP_GPU_COMPOSITE)
+WGPUSampler TextureManager::get_or_create_sampler(SamplerType type) {
+  auto it = samplers_.find(type);
+  if (it != samplers_.end()) {
+    return it->second;
+  }
+
+  WGPUSamplerDescriptor desc = {};
+  desc.lodMinClamp = 0.0f;
+  desc.lodMaxClamp = 1.0f;
+  desc.maxAnisotropy = 1;
+
+  switch (type) {
+  case SamplerType::LinearClamp:
+    desc.addressModeU = WGPUAddressMode_ClampToEdge;
+    desc.addressModeV = WGPUAddressMode_ClampToEdge;
+    desc.magFilter = WGPUFilterMode_Linear;
+    desc.minFilter = WGPUFilterMode_Linear;
+    desc.mipmapFilter = WGPUMipmapFilterMode_Linear;
+    break;
+  case SamplerType::LinearRepeat:
+    desc.addressModeU = WGPUAddressMode_Repeat;
+    desc.addressModeV = WGPUAddressMode_Repeat;
+    desc.magFilter = WGPUFilterMode_Linear;
+    desc.minFilter = WGPUFilterMode_Linear;
+    desc.mipmapFilter = WGPUMipmapFilterMode_Linear;
+    break;
+  case SamplerType::NearestClamp:
+    desc.addressModeU = WGPUAddressMode_ClampToEdge;
+    desc.addressModeV = WGPUAddressMode_ClampToEdge;
+    desc.magFilter = WGPUFilterMode_Nearest;
+    desc.minFilter = WGPUFilterMode_Nearest;
+    desc.mipmapFilter = WGPUMipmapFilterMode_Nearest;
+    break;
+  case SamplerType::NearestRepeat:
+    desc.addressModeU = WGPUAddressMode_Repeat;
+    desc.addressModeV = WGPUAddressMode_Repeat;
+    desc.magFilter = WGPUFilterMode_Nearest;
+    desc.minFilter = WGPUFilterMode_Nearest;
+    desc.mipmapFilter = WGPUMipmapFilterMode_Nearest;
+    break;
+  }
+
+  WGPUSampler sampler = wgpuDeviceCreateSampler(device_, &desc);
+  samplers_[type] = sampler;
+  return sampler;
+}
+
 void TextureManager::dispatch_composite(
     const std::string& func_name, WGPUTexture target,
     const GpuProceduralParams& params, const void* uniform_data,
-    size_t uniform_size, const std::vector<WGPUTextureView>& input_views) {
+    size_t uniform_size, const std::vector<WGPUTextureView>& input_views,
+    SamplerType sampler_type) {
   auto it = compute_pipelines_.find(func_name);
   if (it == compute_pipelines_.end()) {
     return; // Pipeline not created yet
@@ -521,7 +557,7 @@ void TextureManager::dispatch_composite(
   // Binding N: Sampler
   if (num_inputs > 0) {
     bg_entries[2 + num_inputs].binding = 2 + num_inputs;
-    bg_entries[2 + num_inputs].sampler = linear_sampler_;
+    bg_entries[2 + num_inputs].sampler = get_or_create_sampler(sampler_type);
   }
 
   // Create bind group layout (must match pipeline)
@@ -593,7 +629,8 @@ void TextureManager::dispatch_composite(
 void TextureManager::create_gpu_composite_texture(
     const std::string& name, const std::string& shader_func,
     const char* shader_code, const void* uniform_data, size_t uniform_size,
-    int width, int height, const std::vector<std::string>& input_names) {
+    int width, int height, const std::vector<std::string>& input_names,
+    SamplerType sampler) {
   // Create pipeline if needed
   get_or_create_compute_pipeline(shader_func, shader_code, uniform_size,
                                  (int)input_names.size());
@@ -625,7 +662,7 @@ void TextureManager::create_gpu_composite_texture(
   // Dispatch composite shader
   GpuProceduralParams params = {width, height, nullptr, 0};
   dispatch_composite(shader_func, texture, params, uniform_data, uniform_size,
-                    input_views);
+                    input_views, sampler);
 
   // Create view
   WGPUTextureViewDescriptor view_desc = {};
diff --git a/src/gpu/texture_manager.h b/src/gpu/texture_manager.h
index 86d1f63..5a2b9f8 100644
--- a/src/gpu/texture_manager.h
+++ b/src/gpu/texture_manager.h
@@ -52,6 +52,13 @@ class TextureManager {
                                const GpuProceduralParams& params);
 
 #if !defined(STRIP_GPU_COMPOSITE)
+  enum class SamplerType {
+    LinearClamp,
+    LinearRepeat,
+    NearestClamp,
+    NearestRepeat
+  };
+
   // GPU composite generation (multi-input textures)
   void create_gpu_composite_texture(const std::string& name,
                                     const std::string& shader_func,
@@ -59,7 +66,8 @@ class TextureManager {
                                     const void* uniform_data,
                                     size_t uniform_size,
                                     int width, int height,
-                                    const std::vector<std::string>& input_names);
+                                    const std::vector<std::string>& input_names,
+                                    SamplerType sampler = SamplerType::LinearClamp);
 #endif
 
 #if !defined(STRIP_ALL)
@@ -91,7 +99,8 @@ class TextureManager {
   void dispatch_composite(const std::string& func_name, WGPUTexture target,
                          const GpuProceduralParams& params,
                          const void* uniform_data, size_t uniform_size,
-                         const std::vector<WGPUTextureView>& input_views);
+                         const std::vector<WGPUTextureView>& input_views,
+                         SamplerType sampler_type);
 #endif
 
   WGPUDevice device_;
@@ -99,6 +108,7 @@ class TextureManager {
   std::map<std::string, GpuTexture> textures_;
   std::map<std::string, ComputePipelineInfo> compute_pipelines_;
 #if !defined(STRIP_GPU_COMPOSITE)
-  WGPUSampler linear_sampler_;
+  WGPUSampler get_or_create_sampler(SamplerType type);
+  std::map<SamplerType, WGPUSampler> samplers_;
 #endif
 };