From 0475f171100b9c5dd538dd63c2f9ecd7ebcb1179 Mon Sep 17 00:00:00 2001
From: Peder Bergebakken Sundt <pbsds@hotmail.com>
Date: Fri, 22 Mar 2019 00:05:50 +0100
Subject: [PATCH] Small optimization, no having to recompute a matrix for all
 objects

---
 src/renderlogic.cpp | 8 ++++----
 src/sceneGraph.cpp  | 6 ++++++
 src/sceneGraph.hpp  | 1 +
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/renderlogic.cpp b/src/renderlogic.cpp
index 7ba8f72..9bafdb9 100644
--- a/src/renderlogic.cpp
+++ b/src/renderlogic.cpp
@@ -60,8 +60,10 @@ void initRenderer(GLFWwindow* window, CommandLineOptions options) {
 
 // traverses and updates matricies
 void updateNodeTransformations(SceneNode* node, mat4 transformationThusFar, mat4 const& V, mat4 const& P) {
-    mat4 transformationMatrix
-        = glm::translate(mat4(1.0), node->position)
+    mat4 M = (node->has_no_transforms())
+        ? transformationThusFar
+        : transformationThusFar
+        * glm::translate(mat4(1.0), node->position)
         * glm::translate(mat4(1.0), node->referencePoint)
         * glm::rotate(mat4(1.0), node->rotation.z, vec3(0,0,1))
         * glm::rotate(mat4(1.0), node->rotation.y, vec3(0,1,0))
@@ -69,8 +71,6 @@ void updateNodeTransformations(SceneNode* node, mat4 transformationThusFar, mat4
         * glm::scale(mat4(1.0), node->scale)
         * glm::translate(mat4(1.0), -node->referencePoint);
 
-    mat4 M = transformationThusFar * transformationMatrix;
-
     node->MV = V*M;
     node->MVP = P*node->MV;
     node->MVnormal = glm::inverse(glm::transpose(node->MV));
diff --git a/src/sceneGraph.cpp b/src/sceneGraph.cpp
index b17de6e..b27e9eb 100644
--- a/src/sceneGraph.cpp
+++ b/src/sceneGraph.cpp
@@ -77,6 +77,12 @@ void SceneNode::setMaterial(const Material& mat, bool recursive) {
 		child->setMaterial(mat, true);
 }
 
+bool SceneNode::has_no_transforms() const {
+	return position.x == 0 && position.y == 0 && position.z == 0
+		&& rotation.x == 0 && rotation.y == 0 && rotation.z == 0
+		&& scale.x    == 1 && scale.y    == 1 && scale.z    == 1;
+}
+
 bool SceneNode::has_transparancy() const {
 	return opacity < 1.0
 		|| t_diffuse && t_diffuse->has_transparancy
diff --git a/src/sceneGraph.hpp b/src/sceneGraph.hpp
index 4aa7042..7f5a771 100644
--- a/src/sceneGraph.hpp
+++ b/src/sceneGraph.hpp
@@ -42,6 +42,7 @@ struct SceneNode {
 				const PNGImage* reflection=nullptr,
 				bool texture_reset=true);
 	void setMaterial(const Material& mat, bool recursive=false);
+	bool has_no_transforms() const;
 	bool has_transparancy() const;
 	SceneNode* clone() const;