From 04039b4e0c9e2a78888ca14a65aebf888b527cd7 Mon Sep 17 00:00:00 2001
From: Evert <imsonotsleepy@gmail.com>
Date: Sun, 15 Apr 2018 15:54:33 +0300
Subject: [PATCH] Don't create new projection matrix each frame

---
 src/Application.cpp |  4 +---
 src/Application.h   |  2 ++
 src/Camera.cpp      | 20 +++++++++++++++++++-
 src/Camera.h        | 15 +++++++++++----
 4 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/src/Application.cpp b/src/Application.cpp
index d6a5203..102ec4b 100644
--- a/src/Application.cpp
+++ b/src/Application.cpp
@@ -241,12 +241,10 @@ void Application::run()
 
 		glm::vec3 cameraPos = m_camera->getPosition();
 
-		glm::mat4 projection = glm::perspective(m_camera->getFOV(), (GLfloat)m_width/(GLfloat)m_height, 0.1f, 100.0f);
 		glm::mat4 model = glm::scale(glm::translate(glm::mat4(1.0f), cameraPos), glm::vec3(50.0f, 50.0f, 50.0f));
 		skyboxShader.use();
-		skyboxShader.setUniform("projectionMatrix", projection);
-		skyboxShader.setUniform("viewMatrix", m_camera->getViewMatrix());
 		skyboxShader.setUniform("modelMatrix", model);
+		m_camera->shaderViewProjection(skyboxShader); // Load view and projection matrices
 
 		glDrawArrays(GL_TRIANGLES, 0, 12*3); // 12*3 indices starting at 0 -> 12 triangles -> 6 squares
 
diff --git a/src/Application.h b/src/Application.h
index 8a4ed67..2acfde3 100644
--- a/src/Application.h
+++ b/src/Application.h
@@ -30,6 +30,8 @@ class Application : public Singleton<Application>
 		void initialize();
 		void exit() { m_run = false; }
 
+		inline glm::vec2 getScreenDimensions() const { return glm::vec2(m_width, m_height); }
+
 		friend class Singleton<Application>;
 	private:
 		int m_width, m_height;
diff --git a/src/Camera.cpp b/src/Camera.cpp
index 302aa5e..2ee6987 100644
--- a/src/Camera.cpp
+++ b/src/Camera.cpp
@@ -17,6 +17,7 @@
 #include "Camera.h"
 
 #include "util/Log.h"
+#include "Application.h"
 
 // TODO: use Roll
 
@@ -32,6 +33,7 @@ Camera::Camera(glm::vec3 position, glm::vec3 up, GLfloat yaw, GLfloat pitch, GLf
 	m_pitch = pitch;
 	m_roll = roll;
 	updateCameraVectors();
+	updateProjection();
 }
 
 Camera::Camera(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat upY, GLfloat upZ, GLfloat yaw, GLfloat pitch, GLfloat roll) : 
@@ -46,6 +48,7 @@ Camera::Camera(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat up
 	m_pitch = pitch;
 	m_roll = roll;
 	updateCameraVectors();
+	updateProjection();
 }
 
 Camera::~Camera()
@@ -58,6 +61,12 @@ glm::mat4 Camera::getViewMatrix()
 	return glm::lookAt(m_position, m_position + m_front, m_up);
 }
 
+void Camera::shaderViewProjection(Shader& shader)
+{
+	shader.setUniform("viewMatrix", getViewMatrix());
+	shader.setUniform("projectionMatrix", m_projection);
+}
+
 void Camera::processKeyboard(Camera_Movement direction, GLfloat deltaTime)
 {
 	GLfloat velocity = m_movementSpeed * deltaTime;
@@ -114,9 +123,18 @@ void Camera::processMouseScroll(GLfloat yoffset)
 	{
 		m_zoom = 45.0f;
 	}
+
+	updateProjection();
 }
 
-void Camera::updateCameraVectors()
+void Camera::updateProjection(void)
+{
+	// Recalculate the projection matrix
+	glm::vec2 screenDims = Application::getInstance().getScreenDimensions();
+	m_projection = glm::perspective(getFOV(), (GLfloat)screenDims.x/(GLfloat)screenDims.y, 0.1f, 100.0f);
+}
+
+void Camera::updateCameraVectors(void)
 {
 	// Calculate the new Front vector
 	glm::vec3 front;
diff --git a/src/Camera.h b/src/Camera.h
index e83ba01..579a283 100644
--- a/src/Camera.h
+++ b/src/Camera.h
@@ -18,6 +18,7 @@
 #define __CAMERA_H__
 
 #include "util/Common.h"
+#include "Shader.h"
 
 // Defines several possible options for camera movement. Used as abstraction to stay away from window-system specific input methods
 enum Camera_Movement {
@@ -42,13 +43,15 @@ public:
 	Camera(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat upY, GLfloat upZ, GLfloat yaw, GLfloat pitch, GLfloat roll);
 	~Camera();
 
-	glm::mat4 getViewMatrix();
-	glm::vec3 getPosition() const { return m_position; }
+	glm::mat4 getViewMatrix(void);
 	void processKeyboard(Camera_Movement direction, GLfloat deltaTime);
 	void processMouseMovement(GLfloat xoffset, GLfloat yoffset, GLboolean constrainPitch);
 	void processMouseScroll(GLfloat yoffset);
 
-	GLfloat getFOV() const { return m_zoom; }
+	void shaderViewProjection(Shader& shader);
+
+	inline GLfloat getFOV() const { return m_zoom; }
+	inline glm::vec3 getPosition(void) const { return m_position; }
 private:
 	glm::vec3 m_position;
 	glm::vec3 m_front;
@@ -66,6 +69,10 @@ private:
 	GLfloat m_mouseSensitivity;
 	GLfloat m_zoom;
 
-	void updateCameraVectors();
+	// The Projection Matrix
+	glm::mat4 m_projection;
+
+	void updateCameraVectors(void);
+	void updateProjection(void);
 };
 #endif // __CAMERA_H__