From b781960632024df2a7cefc5718a366ef75d9b60d Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Fri, 27 Oct 2017 12:05:53 +0200
Subject: [PATCH] Clean up camera code.

---
 src/camera.cpp | 47 ++++++++++++++++++++++++++++++-----------------
 src/camera.hpp | 17 ++++++++++++++---
 src/main.cpp   | 10 ++++++++--
 3 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/src/camera.cpp b/src/camera.cpp
index 132d25c..1f0377a 100644
--- a/src/camera.cpp
+++ b/src/camera.cpp
@@ -1,21 +1,20 @@
 #include <GL/glut.h>
 #include <cmath>
+#include <sstream>
 #include "camera.hpp"
 
 using namespace fmri;
 using namespace std;
 
-static float yaw, pitch;
-
-static float pos[3];
+static Camera& camera = Camera::instance();
 
 static void handleMouseMove(int x, int y)
 {
     const float width = glutGet(GLUT_WINDOW_WIDTH) / 2;
     const float height = glutGet(GLUT_WINDOW_HEIGHT) / 2;
 
-    yaw = (x - width) / width * 180;
-    pitch = (y - height) / height * 90;
+    camera.angle[0] = (x - width) / width * 180;
+    camera.angle[1] = (y - height) / height * 90;
 }
 
 static void move(unsigned char key)
@@ -38,7 +37,7 @@ static void move(unsigned char key)
     }
 
     for (unsigned int i = 0; i < 3; ++i) {
-        pos[i] += speed * dir[i];
+        camera.pos[i] += speed * dir[i];
     }
 }
 
@@ -62,27 +61,41 @@ static void handleKeys(unsigned char key, int, int)
     }
 }
 
-void fmri::registerCameraControls()
+std::string Camera::infoLine()
 {
-    resetCamera();
-    glutPassiveMotionFunc(handleMouseMove);
-    glutKeyboardFunc(handleKeys);
+    stringstream buffer;
+    buffer << "Pos(x,y,z) = (" << pos[0] << ", " << pos[1] << ", " << pos[2] << ")\n";
+    buffer << "Angle(p,y) = (" << angle[0] << ", " << angle[1] << ")\n";
+    return buffer.str();
 }
 
-void fmri::resetCamera()
+void Camera::reset()
 {
-    pitch = 0;
-    yaw = 0;
-
     pos[0] = 0;
     pos[1] = 0;
     pos[2] = 10;
+
+    angle[0] = 0;
+    angle[1] = 0;
 }
 
-void fmri::configureCamera()
+void Camera::configureRenderingContext()
 {
     glLoadIdentity();
-    glRotatef(yaw, 0, 1, 0);
-    glRotatef(pitch, 1, 0, 0);
+    glRotatef(angle[0], 0, 1, 0);
+    glRotatef(angle[1], 1, 0, 0);
     glTranslatef(-pos[0], -pos[1], -pos[2]);
 }
+
+Camera &Camera::instance()
+{
+    static Camera camera;
+    return camera;
+}
+
+void Camera::registerControls()
+{
+    reset();
+    glutPassiveMotionFunc(handleMouseMove);
+    glutKeyboardFunc(handleKeys);
+}
diff --git a/src/camera.hpp b/src/camera.hpp
index b2e553e..936f27d 100644
--- a/src/camera.hpp
+++ b/src/camera.hpp
@@ -1,10 +1,21 @@
 #pragma once
 
+#include <string>
+
 namespace fmri
 {
-    void registerCameraControls();
+    struct Camera {
+        float pos[3];
+        float angle[2];
 
-    void configureCamera();
+        void reset();
+        void configureRenderingContext();
+        void registerControls();
+        std::string infoLine();
 
-    void resetCamera();
+        static Camera& instance();
+
+    private:
+        Camera() = default;
+    };
 }
diff --git a/src/main.cpp b/src/main.cpp
index 766e650..1f6cdac 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -48,7 +48,9 @@ static void render()
     // Clear Color and Depth Buffers
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-    configureCamera();
+    auto& camera = Camera::instance();
+
+    camera.configureRenderingContext();
 
     glBegin(GL_TRIANGLES);
     glVertex3f(-2.0f, -2.0f, 0.0f);
@@ -56,6 +58,9 @@ static void render()
     glVertex3f(0.0f, 2.0f, 0.0);
     glEnd();
 
+    // Draw the status line on screen
+    glRasterPos2i(0, 0);
+
     glutSwapBuffers();
 }
 
@@ -109,7 +114,8 @@ int main(int argc, char *argv[])
     glutDisplayFunc(render);
     glutIdleFunc(render);
     glutReshapeFunc(changeWindowSize);
-    registerCameraControls();
+
+    Camera::instance().registerControls();
 
     glewInit();
     if (!GLEW_VERSION_2_0) {