From 6fb9efea1fd0e4575973719a997602da4b4c4fa5 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke_lau@icloud.com>
Date: Mon, 10 Feb 2020 02:48:03 +0000
Subject: [PATCH] Fix bone offset matrix being unnecessarily inverted

---
 Makefile  |  2 +-
 model.cpp | 22 +++++++++++++---------
 model.hpp |  1 -
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/Makefile b/Makefile
index 42ebf39..2225d19 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 all: bin/main
 
-CXX_FLAGS := -g --std=c++17
+CXX_FLAGS := -g --std=c++17 -Wall
 
 bin/main: model.o material.o image.o skybox.o program.o main.cpp
 	clang++ $(CXX_FLAGS) $^ \
diff --git a/model.cpp b/model.cpp
index 107fda0..f68db4b 100644
--- a/model.cpp
+++ b/model.cpp
@@ -232,11 +232,11 @@ void Model::Node::draw(	const std::vector<Mesh> &meshes,
 	}
 	
 
-	glm::mat4 m = parentTrans * animTrans * aiMatrixToMat4(ai.mTransformation) * model;
+	glm::mat4 m = parentTrans * animTrans * aiMatrixToMat4(ai.mTransformation);
 
-	for (auto child: children) {
-		boneTransforms[std::string(ai.mName.C_Str())] = m;
-	}
+	/* for (auto child: children) { */
+	/* 	boneTransforms[std::string(ai.mName.C_Str())] = m; */
+	/* } */
 	
 	for (unsigned int i: meshIndices) {
 		const Mesh &mesh = meshes[i];
@@ -250,13 +250,17 @@ void Model::Node::draw(	const std::vector<Mesh> &meshes,
 
 			std::string nodeName = pair.first;
 			unsigned int boneId = pair.second.first;
+			// This is actually an inverse-bind matrix
+			// i.e. position of the mesh in bone space
+			// so no need to inverse again!
+			// https://github.com/assimp/assimp/pull/1803/files
 			glm::mat4 boneOffset = pair.second.second;
 
 			glm::mat4 boneTrans(1.f);
-			if (boneTransforms.count(nodeName)) {
-				std::cerr << "got bone transform from map" << std::endl;
-				boneTrans = boneTransforms[nodeName];
-			}
+			/* if (boneTransforms.count(nodeName)) { */
+			/* 	std::cerr << "got bone transform from map" << std::endl; */
+			/* 	boneTrans = boneTransforms[nodeName]; */
+			/* } */
 			for (const Animation anim: animMap->at(nodeName)) {
 				float t = fmod(tick, anim.duration);
 				for (const aiNodeAnim *nodeAnim: anim.nodeAnims) {
@@ -266,7 +270,7 @@ void Model::Node::draw(	const std::vector<Mesh> &meshes,
 				}
 			}
 
-			boneTrans = boneTrans * glm::inverse(boneOffset);
+			boneTrans = boneTrans * boneOffset;
 
 
 			std::string boneLocStr = "bones[" + std::to_string(boneId) + "]";
diff --git a/model.hpp b/model.hpp
index 5c74cb3..2803a7e 100644
--- a/model.hpp
+++ b/model.hpp
@@ -45,7 +45,6 @@ class Model {
 				void draw(const std::vector<Mesh> &meshes, const std::vector<Material> &materials, const Skybox s, const float tick, glm::mat4 parentModel, BoneTransforms boneTransforms) const;
 				const std::vector<Node*> &getChildren() const { return children; }
 				Node* findNode(const aiNode &aiNode);
-				glm::mat4 model = glm::mat4(1);
 				const aiNode &ai;
 
 			private:
-- 
2.30.2