fix: port Hybrid3D effect to sequence v2 architecture

Hybrid3D was calling Renderer3D::render() which creates its own command
encoder, bypassing the sequence system. Now uses renderer_.draw() with
the passed encoder.

Also adds texture blit support for RotatingCube compositing.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

2 files changed, 16 insertions, 3 deletions

diff --git a/src/gpu/sequence.cc b/src/gpu/sequence.cc
index 62c2933..0a0cb1e 100644
--- a/src/gpu/sequence.cc
+++ b/src/gpu/sequence.cc
@@ -92,6 +92,16 @@ NodeRegistry::get_output_views(const std::vector<std::string>& names) {
   return views;
 }
 
+WGPUTexture NodeRegistry::get_texture(const std::string& name) {
+  auto alias_it = aliases_.find(name);
+  if (alias_it != aliases_.end()) {
+    return get_texture(alias_it->second);
+  }
+  auto it = nodes_.find(name);
+  FATAL_CHECK(it != nodes_.end(), "Node not found: %s\n", name.c_str());
+  return it->second.texture;
+}
+
 void NodeRegistry::resize(int width, int height) {
   default_width_ = width;
   default_height_ = height;
@@ -141,15 +151,15 @@ void NodeRegistry::create_texture(Node& node) {
   switch (node.type) {
   case NodeType::U8X4_NORM:
     format = WGPUTextureFormat_RGBA8Unorm;
-    usage = (WGPUTextureUsage)(WGPUTextureUsage_RenderAttachment | WGPUTextureUsage_TextureBinding);
+    usage = (WGPUTextureUsage)(WGPUTextureUsage_RenderAttachment | WGPUTextureUsage_TextureBinding | WGPUTextureUsage_CopySrc | WGPUTextureUsage_CopyDst);
     break;
   case NodeType::F32X4:
     format = WGPUTextureFormat_RGBA32Float;
-    usage = (WGPUTextureUsage)(WGPUTextureUsage_RenderAttachment | WGPUTextureUsage_TextureBinding);
+    usage = (WGPUTextureUsage)(WGPUTextureUsage_RenderAttachment | WGPUTextureUsage_TextureBinding | WGPUTextureUsage_CopySrc | WGPUTextureUsage_CopyDst);
     break;
   case NodeType::F16X8:
     format = WGPUTextureFormat_RGBA16Float; // WebGPU doesn't have 8-channel, use RGBA16
-    usage = (WGPUTextureUsage)(WGPUTextureUsage_RenderAttachment | WGPUTextureUsage_TextureBinding);
+    usage = (WGPUTextureUsage)(WGPUTextureUsage_RenderAttachment | WGPUTextureUsage_TextureBinding | WGPUTextureUsage_CopySrc | WGPUTextureUsage_CopyDst);
     break;
   case NodeType::DEPTH24:
     format = WGPUTextureFormat_Depth24Plus;
diff --git a/src/gpu/sequence.h b/src/gpu/sequence.h
index a33dedb..e96e183 100644
--- a/src/gpu/sequence.h
+++ b/src/gpu/sequence.h
@@ -62,6 +62,9 @@ class NodeRegistry {
   std::vector<WGPUTextureView>
   get_output_views(const std::vector<std::string>& names);
 
+  // Retrieve texture (for blits)
+  WGPUTexture get_texture(const std::string& name);
+
   // Resize all nodes
   void resize(int width, int height);