From b5222f08e8ad25064750f033150552948a494988 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <c.oelckers@zdoom.fake>
Date: Sat, 29 Oct 2016 10:16:00 +0200
Subject: [PATCH] - implemented dot and cross products (not that I'd ever
 expect these to become useful in a game like Doom...)

---
 src/scripting/codegeneration/codegen.cpp | 70 ++++++++++++++++++++++++
 src/scripting/codegeneration/codegen.h   | 21 +++++++
 src/scripting/zscript/zcc_compile.cpp    |  9 ++-
 3 files changed, 95 insertions(+), 5 deletions(-)

diff --git a/src/scripting/codegeneration/codegen.cpp b/src/scripting/codegeneration/codegen.cpp
index 4c048c452..039e428ff 100644
--- a/src/scripting/codegeneration/codegen.cpp
+++ b/src/scripting/codegeneration/codegen.cpp
@@ -3438,6 +3438,76 @@ ExpEmit FxBinaryLogical::Emit(VMFunctionBuilder *build)
 //
 //==========================================================================
 
+FxDotCross::FxDotCross(int o, FxExpression *l, FxExpression *r)
+	: FxExpression(EFX_DotCross, l->ScriptPosition)
+{
+	Operator = o;
+	left = l;
+	right = r;
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+FxDotCross::~FxDotCross()
+{
+	SAFE_DELETE(left);
+	SAFE_DELETE(right);
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+FxExpression *FxDotCross::Resolve(FCompileContext& ctx)
+{
+	CHECKRESOLVED();
+	RESOLVE(left, ctx);
+	RESOLVE(right, ctx);
+	ABORT(right && left);
+
+	if (!left->IsVector() || left->ValueType != right->ValueType || (Operator == TK_Cross && left->ValueType != TypeVector3))
+	{
+		ScriptPosition.Message(MSG_ERROR, "Incompatible operants for %sproduct", Operator == TK_Cross ? "cross-" : "dot-");
+		delete this;
+		return nullptr;
+	}
+	ValueType = Operator == TK_Cross ? (PType*)TypeVector3 : TypeFloat64;
+	return this;
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
+ExpEmit FxDotCross::Emit(VMFunctionBuilder *build)
+{
+	// This is not the "right" way to do these, but it works for now.
+	// (Problem: No information sharing is done between nodes to reduce the
+	// code size if you have something like a1 && a2 && a3 && ... && an.)
+	ExpEmit to(build, ValueType->GetRegType(), ValueType->GetRegCount());
+	ExpEmit op1 = left->Emit(build);
+	ExpEmit op2 = right->Emit(build);
+	int op = Operator == TK_Cross ? OP_CROSSV_RR : left->ValueType == TypeVector3 ? OP_DOTV3_RR : OP_DOTV2_RR;
+	build->Emit(op, to.RegNum, op1.RegNum, op2.RegNum);
+	op1.Free(build);
+	op2.Free(build);
+	return to;
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
 FxConditional::FxConditional(FxExpression *c, FxExpression *t, FxExpression *f)
 : FxExpression(EFX_Conditional, c->ScriptPosition)
 {
diff --git a/src/scripting/codegeneration/codegen.h b/src/scripting/codegeneration/codegen.h
index 01d63eaf8..570575bb9 100644
--- a/src/scripting/codegeneration/codegen.h
+++ b/src/scripting/codegeneration/codegen.h
@@ -228,6 +228,7 @@ enum EFxType
 	EFX_AssignSelf,
 	EFX_Binary,	// one token fits all, the operator is enough to distinguish them.
 	EFX_BinaryLogical,
+	EFX_DotCross,
 	EFX_Conditional,
 	EFX_Abs,
 	EFX_ATan2,
@@ -905,6 +906,26 @@ public:
 	ExpEmit Emit(VMFunctionBuilder *build);
 };
 
+//==========================================================================
+//
+//	FxBinaryLogical
+//
+//==========================================================================
+
+class FxDotCross : public FxExpression
+{
+public:
+	int				Operator;
+	FxExpression		*left;
+	FxExpression		*right;
+
+	FxDotCross(int, FxExpression*, FxExpression*);
+	~FxDotCross();
+	FxExpression *Resolve(FCompileContext&);
+
+	ExpEmit Emit(VMFunctionBuilder *build);
+};
+
 //==========================================================================
 //
 //	FxConditional
diff --git a/src/scripting/zscript/zcc_compile.cpp b/src/scripting/zscript/zcc_compile.cpp
index f1a06d584..294763f9b 100644
--- a/src/scripting/zscript/zcc_compile.cpp
+++ b/src/scripting/zscript/zcc_compile.cpp
@@ -2680,14 +2680,13 @@ FxExpression *ZCCCompiler::ConvertNode(ZCC_TreeNode *ast)
 		case PEX_ArrayAccess:
 			return new FxArrayElement(left, right);
 
-			// todo: These do not have representations in DECORATE and no implementation exists yet.
-		case PEX_Concat:
-		case PEX_Is:
-
-			// vector operations will be done later.
 		case PEX_CrossProduct:
 		case PEX_DotProduct:
+			return new FxDotCross(tok, left, right);
 
+				// todo: These do not have representations in DECORATE and no implementation exists yet.
+		case PEX_Concat:
+		case PEX_Is:
 
 		default:
 			I_Error("Binary operator %d not implemented yet", op);