From 9d6b655d2f476b44bba977cc52c83be514d0fd30 Mon Sep 17 00:00:00 2001
From: edobrowo <ethan.dobrowolski@gmail.com>
Date: Fri, 27 Sep 2024 15:11:31 -0400
Subject: [PATCH] Initial implementation of space-dependent HwViewDirectionNode

---
 .../Nodes/HwViewDirectionNode.cpp             | 57 +++++++++++++++----
 1 file changed, 46 insertions(+), 11 deletions(-)

diff --git a/source/MaterialXGenShader/Nodes/HwViewDirectionNode.cpp b/source/MaterialXGenShader/Nodes/HwViewDirectionNode.cpp
index 819ac93029..e97aa2f494 100644
--- a/source/MaterialXGenShader/Nodes/HwViewDirectionNode.cpp
+++ b/source/MaterialXGenShader/Nodes/HwViewDirectionNode.cpp
@@ -14,29 +14,56 @@ ShaderNodeImplPtr HwViewDirectionNode::create()
     return std::make_shared<HwViewDirectionNode>();
 }
 
-void HwViewDirectionNode::createVariables(const ShaderNode&, GenContext&, Shader& shader) const
+void HwViewDirectionNode::createVariables(const ShaderNode& node, GenContext&, Shader& shader) const
 {
-    ShaderStage& vs = shader.getStage(Stage::VERTEX);
-    ShaderStage& ps = shader.getStage(Stage::PIXEL);
+    ShaderStage vs = shader.getStage(Stage::VERTEX);
+    ShaderStage ps = shader.getStage(Stage::PIXEL);
 
     addStageInput(HW::VERTEX_INPUTS, Type::VECTOR3, HW::T_IN_POSITION, vs);
-    addStageConnector(HW::VERTEX_DATA, Type::VECTOR3, HW::T_POSITION_WORLD, vs, ps);
-    addStageUniform(HW::PRIVATE_UNIFORMS, Type::VECTOR3, HW::T_VIEW_POSITION, ps);
+
+    const ShaderInput* spaceInput = node.getInput(SPACE);
+    const int space = spaceInput ? spaceInput->getValue()->asA<int>() : OBJECT_SPACE;
+    if (space == WORLD_SPACE)
+    {
+        addStageConnector(HW::VERTEX_DATA, Type::VECTOR3, HW::T_POSITION_WORLD, vs, ps);
+        addStageUniform(HW::PRIVATE_UNIFORMS, Type::VECTOR3, HW::T_VIEW_POSITION, ps);
+    }
+    else
+    {
+        addStageConnector(HW::VERTEX_DATA, Type::VECTOR3, HW::T_POSITION_OBJECT, vs, ps);
+        addStageUniform(HW::PRIVATE_UNIFORMS, Type::VECTOR3, HW::T_VIEW_POSITION, ps);
+        addStageUniform(HW::PRIVATE_UNIFORMS, Type::MATRIX44, HW::T_WORLD_INVERSE_TRANSPOSE_MATRIX, ps);
+    }
 }
 
 void HwViewDirectionNode::emitFunctionCall(const ShaderNode& node, GenContext& context, ShaderStage& stage) const
 {
     const HwShaderGenerator& shadergen = static_cast<const HwShaderGenerator&>(context.getShaderGenerator());
 
+    const ShaderInput* spaceInput = node.getInput(SPACE);
+    const int space = spaceInput ? spaceInput->getValue()->asA<int>() : OBJECT_SPACE;
+
     DEFINE_SHADER_STAGE(stage, Stage::VERTEX)
     {
         VariableBlock& vertexData = stage.getOutputBlock(HW::VERTEX_DATA);
         const string prefix = shadergen.getVertexDataPrefix(vertexData);
-        ShaderPort* position = vertexData[HW::T_POSITION_WORLD];
-        if (!position->isEmitted())
+        if (space == WORLD_SPACE)
         {
-            position->setEmitted();
-            shadergen.emitLine(prefix + position->getVariable() + " = hPositionWorld.xyz", stage);
+            ShaderPort* position = vertexData[HW::T_POSITION_WORLD];
+            if (!position->isEmitted())
+            {
+                position->setEmitted();
+                shadergen.emitLine(prefix + position->getVariable() + " = hPositionWorld.xyz", stage);
+            }
+        }
+        else
+        {
+            ShaderPort* position = vertexData[HW::T_POSITION_OBJECT];
+            if (!position->isEmitted())
+            {
+                position->setEmitted();
+                shadergen.emitLine(prefix + position->getVariable() + " = " + HW::T_IN_POSITION, stage);
+            }
         }
     }
 
@@ -44,10 +71,18 @@ void HwViewDirectionNode::emitFunctionCall(const ShaderNode& node, GenContext& c
     {
         VariableBlock& vertexData = stage.getInputBlock(HW::VERTEX_DATA);
         const string prefix = shadergen.getVertexDataPrefix(vertexData);
-        ShaderPort* position = vertexData[HW::T_POSITION_WORLD];
         shadergen.emitLineBegin(stage);
         shadergen.emitOutput(node.getOutput(), true, false, context, stage);
-        shadergen.emitString(" = normalize(" + prefix + position->getVariable() + " - " + HW::T_VIEW_POSITION + ")", stage);
+        if (space == WORLD_SPACE)
+        {
+            ShaderPort* position = vertexData[HW::T_POSITION_WORLD];
+            shadergen.emitString(" = normalize(" + prefix + position->getVariable() + " - " + HW::T_VIEW_POSITION + ")", stage);
+        }
+        else
+        {
+            ShaderPort* position = vertexData[HW::T_POSITION_OBJECT];
+            shadergen.emitString(" = normalize(" + prefix + position->getVariable() + " - (" + HW::T_WORLD_INVERSE_TRANSPOSE_MATRIX + " * vec4(" + HW::T_VIEW_POSITION + ", 0.0)).xyz)", stage);
+        }
         shadergen.emitLineEnd(stage);
     }
 }