From 622c5ca05d48f543f4387a69cad4c84c9d3d310c Mon Sep 17 00:00:00 2001
From: Matthew Mott <orbweaver3d@gmail.com>
Date: Tue, 9 Mar 2021 20:54:26 +0000
Subject: [PATCH] Add a test for omni light texture matrix

Add a new getRendererLight() method to the ILightNode interface, and use this
to retrieve and examine the texture transformation matrix of a simple omni
light.
---
 include/ilightnode.h                 | 11 +++---
 radiantcore/entity/light/LightNode.h |  3 ++
 test/CMakeLists.txt                  |  1 +
 test/Renderer.cpp                    | 52 ++++++++++++++++++++++++++++
 4 files changed, 62 insertions(+), 5 deletions(-)
 create mode 100644 test/Renderer.cpp

diff --git a/include/ilightnode.h b/include/ilightnode.h
index 17853aa209..892c1448c3 100644
--- a/include/ilightnode.h
+++ b/include/ilightnode.h
@@ -5,9 +5,9 @@
 #include "math/AABB.h"
 
 /**
- * LightNodes derive from this class. 
+ * LightNodes derive from this class.
  * It's mainly used to determine the selectable part
- * of the light, which is usually the small "diamond" in 
+ * of the light, which is usually the small "diamond" in
  * the center.
  */
 class ILightNode
@@ -15,9 +15,10 @@ class ILightNode
 public:
     virtual ~ILightNode() {}
 
-    /** 
-	 * greebo: Get the AABB of the Light "Diamond" representation.
-     */
+    /// Return the RendererLight instance for this light node
+    virtual const RendererLight& getRendererLight() const = 0;
+
+	/// Get the AABB of the Light "Diamond" representation.
     virtual AABB getSelectAABB() const = 0;
 };
 typedef std::shared_ptr<ILightNode> ILightNodePtr;
diff --git a/radiantcore/entity/light/LightNode.h b/radiantcore/entity/light/LightNode.h
index d4d2f6d37f..e234ecd82e 100644
--- a/radiantcore/entity/light/LightNode.h
+++ b/radiantcore/entity/light/LightNode.h
@@ -58,6 +58,9 @@ class LightNode :
 public:
 	static LightNodePtr Create(const IEntityClassPtr& eclass);
 
+    // ILightNode implementation
+    const RendererLight& getRendererLight() const { return _light; }
+
 	// RenderEntity implementation
 	virtual float getShaderParm(int parmNum) const override;
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 8fb7d04ca6..035cb98cbb 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -25,6 +25,7 @@ add_executable(drtest
                PatchIterators.cpp
                PatchWelding.cpp
                Prefabs.cpp
+               Renderer.cpp
                SelectionAlgorithm.cpp
                Selection.cpp
                VFS.cpp
diff --git a/test/Renderer.cpp b/test/Renderer.cpp
new file mode 100644
index 0000000000..0e5b1eb19e
--- /dev/null
+++ b/test/Renderer.cpp
@@ -0,0 +1,52 @@
+#include "RadiantTest.h"
+
+#include "ieclass.h"
+#include "ientity.h"
+#include "ilightnode.h"
+#include "math/Matrix4.h"
+
+namespace test
+{
+
+using RendererTest = RadiantTest;
+
+IEntityNodePtr createByClassName(const std::string& className)
+{
+    auto cls = GlobalEntityClassManager().findClass(className);
+    return GlobalEntityModule().createEntity(cls);
+}
+
+TEST_F(RendererTest, CreateLightNode)
+{
+    auto light = createByClassName("light");
+    ILightNodePtr node = Node_getLightNode(light);
+    ASSERT_TRUE(node);
+}
+
+TEST_F(RendererTest, GetLightTextureTransform)
+{
+    auto light = createByClassName("light");
+    Entity* lightEnt = Node_getEntity(light);
+    ASSERT_TRUE(lightEnt);
+
+    // Set a radius of 10 units in each dimension
+    lightEnt->setKeyValue("light_radius", "10 10 10");
+
+    // Get the RendererLight
+    ILightNodePtr node = Node_getLightNode(light);
+    ASSERT_TRUE(node);
+    const RendererLight& rLight = node->getRendererLight();
+
+    // Get the texture matrix transform
+    Matrix4 texMat = rLight.getLightTextureTransformation();
+
+    // Radius is symmetric around the origin, so the scale factor should be
+    // 1/20, with an offset to map the resulting light-space coordinates from
+    // [-0.5, 0.5] onto ST coordinates spanning [0, 1]
+    EXPECT_EQ(texMat, Matrix4::byRows(0.05, 0, 0, 0.5,
+                                      0, 0.05, 0, 0.5,
+                                      0, 0, 0.05, 0.5,
+                                      0, 0, 0, 1));
+}
+
+}
\ No newline at end of file