Debugger: Implement FRAGMENT_WINDOW_SPACE_POSITION

docs/debugger.md

@@ -51,8 +51,6 @@ Within this `RUN` block, you may declare any number of `THREAD` command blocks t
 
   Defines a sequence of debugger commands to run when the shader invocation for the fragment with the given window space position is executed.
 
-  TODO(bclayton): This has not yet been implemented.
-
 Each of the `THREAD` commands begins a block that must be terminated with an `END`.
 
 Within each `THREAD` command block, you may use any of the following commands to control execution of the shader, and to verify the debugger's behaviour:

src/amberscript/parser.cc

@@ -1872,6 +1872,24 @@ Result Parser::ParseDebugThread(debug::Events* dbg) {
     }
 
     dbg->BreakOnVertexIndex(vertex_index, thread);
+  } else if (token->AsString() == "FRAGMENT_WINDOW_SPACE_POSITION") {
+    token = tokenizer_->NextToken();
+    if (!token->IsInteger())
+      return Result("expected x unsigned integer coordinate");
+    auto x = token->AsUint32();
+
+    token = tokenizer_->NextToken();
+    if (!token->IsInteger())
+      return Result("expected y unsigned integer coordinate");
+    auto y = token->AsUint32();
+
+    auto thread = debug::ThreadScript::Create();
+    auto result = ParseDebugThreadBody(thread.get());
+    if (!result.IsSuccess()) {
+      return result;
+    }
+
+    dbg->BreakOnFragmentWindowSpacePosition(x, y, thread);
   } else {
     return Result("expected GLOBAL_INVOCATION_ID or VERTEX_INDEX");
   }

src/debug.cc

@@ -51,6 +51,15 @@ class ScriptImpl : public Script {
         [=](Events* events) { events->BreakOnVertexIndex(index, thread); });
   }
 
+  void BreakOnFragmentWindowSpacePosition(
+      uint32_t x,
+      uint32_t y,
+      const std::shared_ptr<const ThreadScript>& thread) override {
+    sequence_.emplace_back([=](Events* events) {
+      events->BreakOnFragmentWindowSpacePosition(x, y, thread);
+    });
+  }
+
  private:
   using Event = std::function<void(Events*)>;
   std::vector<Event> sequence_;

src/debug.h

@@ -92,10 +92,19 @@ class Events {
 
   /// BreakOnVertexIndex instructs the debugger to set a breakpoint at the start
   /// of the vertex shader program for the invocation with the vertex index
-  /// [index], and run the |ThreadScript| once the breakpoint is hit.
+  /// |index|, and run the |ThreadScript| once the breakpoint is hit.
   virtual void BreakOnVertexIndex(
       uint32_t index,
       const std::shared_ptr<const ThreadScript>&) = 0;
+
+  /// BreakOnFragmentWindowSpacePosition instructs the debugger to set a
+  /// breakpoint at the start of the fragment shader program for the invocation
+  /// with the window space coordinate [x, y], and run the |ThreadScript| once
+  /// the breakpoint is hit.
+  virtual void BreakOnFragmentWindowSpacePosition(
+      uint32_t x,
+      uint32_t y,
+      const std::shared_ptr<const ThreadScript>&) = 0;
 };
 
 /// ThreadScript is a specialization of the |amber::debug::Thread| interface,