From b9a007dd517072c3aa57bb24348f5630db8beccb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mario=20H=C3=BCttel?= <mario.huettel@gmx.net>
Date: Thu, 26 Mar 2020 23:03:49 +0100
Subject: [PATCH] Change normal matrix from 4x4 to 3x3

---
 include/opengl-playground/openglgraphics.hpp | 6 +++---
 include/opengl-playground/openglshader.hpp   | 1 +
 shaders/mesh-vertex.glsl                     | 4 ++--
 src/mesh.cpp                                 | 2 +-
 src/openglgraphics.cpp                       | 8 +++-----
 src/openglshader.cpp                         | 8 ++++++++
 6 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/include/opengl-playground/openglgraphics.hpp b/include/opengl-playground/openglgraphics.hpp
index f44ccfe..d0bbc30 100644
--- a/include/opengl-playground/openglgraphics.hpp
+++ b/include/opengl-playground/openglgraphics.hpp
@@ -15,12 +15,12 @@ class OpenGlGraphics
 		virtual void realize() = 0;
 		virtual void render() = 0;
 		void setModelMatrix(const glm::mat4 &model_matrix);
-		glm::mat4 getModelMatrix();
-		glm::mat4 getNormalMatrix();
+		const glm::mat4 &getModelMatrix();
+		const glm::mat3 &getNormalMatrix();
 	protected:
 		std::shared_ptr<OpenGlShaderProgram> shaderprog;
 		glm::mat4 model_matrix;
-		glm::mat4 normal_matrix;
+		glm::mat3 normal_matrix;
 };
 
 #endif // OPENGLGRAPHICS_H
diff --git a/include/opengl-playground/openglshader.hpp b/include/opengl-playground/openglshader.hpp
index e217ee3..9e0a5f3 100644
--- a/include/opengl-playground/openglshader.hpp
+++ b/include/opengl-playground/openglshader.hpp
@@ -21,6 +21,7 @@ class OpenGlShaderProgram
 		void setUniformVec2(const std::string &uniform, float *vector);
 		void setUniformVec3(const std::string &uniform, const glm::vec3 &vector);
 		void setUniformMat4(const std::string &uniform, const glm::mat4 &matrix);
+		void setUniformMat3(const std::string &uniform, const glm::mat3 &matrix);
 		void setUniformVec4(const std::string &uniform, const glm::vec4 &vector);
 		void setUniformBool(const std::string &uniform, bool value);
 	private:
diff --git a/shaders/mesh-vertex.glsl b/shaders/mesh-vertex.glsl
index 9a45ed7..7547d72 100644
--- a/shaders/mesh-vertex.glsl
+++ b/shaders/mesh-vertex.glsl
@@ -5,7 +5,7 @@ layout (location = 1) in vec3 aInputNormal;
 layout (location = 2) in vec2 aTextureCoord;
 
 uniform mat4 model_matrix;
-uniform mat4 normal_matrix;
+uniform mat3 normal_matrix;
 uniform mat4 projection_view_matrix;
 uniform vec3 camera_position;
 
@@ -17,7 +17,7 @@ out vec3 ViewPos;
 void main()
 {
 	gl_Position = projection_view_matrix * model_matrix * vec4(aInputPosition, 1.0);
-	Normal = vec3(normal_matrix * vec4(aInputNormal, 0.0));
+	Normal = normal_matrix *  aInputNormal;
 	FragPos = vec3(model_matrix * vec4(aInputPosition, 1.0));
 	TexCoord = aTextureCoord;
 	ViewPos = camera_position;
diff --git a/src/mesh.cpp b/src/mesh.cpp
index e8822d1..9e1712e 100644
--- a/src/mesh.cpp
+++ b/src/mesh.cpp
@@ -47,7 +47,7 @@ void Mesh::render(const glm::mat4 &model_matrix, const glm::mat4 &normal_matrix)
 {
 	this->shaderprog->use();
 	this->shaderprog->setUniformMat4("model_matrix", model_matrix);
-	this->shaderprog->setUniformMat4("normal_matrix", normal_matrix);
+	this->shaderprog->setUniformMat3("normal_matrix", normal_matrix);
 	this->shaderprog->setUniformMat4("projection_view_matrix", GlobalCanvasSettings::getPVMatrix());
 	this->shaderprog->setUniformVec3("camera_position", GlobalCanvasSettings::getCameraPosition());
 
diff --git a/src/openglgraphics.cpp b/src/openglgraphics.cpp
index 5a0d706..12d3f1e 100644
--- a/src/openglgraphics.cpp
+++ b/src/openglgraphics.cpp
@@ -1,7 +1,5 @@
 #include <opengl-playground/openglgraphics.hpp>
 
-
-
 OpenGlGraphics::OpenGlGraphics(std::shared_ptr<OpenGlShaderProgram>shader_prog)
 {
 	this->shaderprog = shader_prog;
@@ -16,15 +14,15 @@ OpenGlGraphics::~OpenGlGraphics()
 void OpenGlGraphics::setModelMatrix(const glm::mat4 &model_matrix)
 {
 	this->model_matrix = model_matrix;
-	this->normal_matrix = glm::transpose(glm::inverse(model_matrix));
+	this->normal_matrix = glm::mat3(glm::transpose(glm::inverse(model_matrix)));
 }
 
-glm::mat4 OpenGlGraphics::getModelMatrix()
+const glm::mat4 &OpenGlGraphics::getModelMatrix()
 {
 	return this->model_matrix;
 }
 
-glm::mat4 OpenGlGraphics::getNormalMatrix()
+const glm::mat3 &OpenGlGraphics::getNormalMatrix()
 {
 	return this->normal_matrix;
 }
diff --git a/src/openglshader.cpp b/src/openglshader.cpp
index 0b1c8ca..91d52dc 100644
--- a/src/openglshader.cpp
+++ b/src/openglshader.cpp
@@ -200,6 +200,14 @@ void OpenGlShaderProgram::setUniformMat4(const std::string &uniform, const glm::
 	}
 }
 
+void OpenGlShaderProgram::setUniformMat3(const std::string &uniform, const glm::mat3 &matrix)
+{
+	int loc = this->getUniformLoc(uniform);
+	if (loc >= 0) {
+		glUniformMatrix3fv(loc, 1, GL_FALSE, &matrix[0][0]);
+	}
+}
+
 void OpenGlShaderProgram::setUniformVec4(const std::string &uniform, const glm::vec4 &vector)
 {
 	int loc = this->getUniformLoc(uniform);