From af9286fbc9277b4d69c7f034a3945efbbf479a14 Mon Sep 17 00:00:00 2001
From: David Vereb <dvereb@dvereb.com>
Date: Tue, 15 Jun 2021 21:13:59 -0400
Subject: [PATCH] Added missing camera directory.

---
 camera/Camera.cpp | 117 ++++++++++++++++++++++++++++++++++++++++++++++
 camera/Camera.h   |  36 ++++++++++++++
 2 files changed, 153 insertions(+)
 create mode 100644 camera/Camera.cpp
 create mode 100644 camera/Camera.h

diff --git a/camera/Camera.cpp b/camera/Camera.cpp
new file mode 100644
index 0000000..ed10cca
--- /dev/null
+++ b/camera/Camera.cpp
@@ -0,0 +1,117 @@
+#include <stdio.h>
+#include <math.h>
+#include <GL/glut.h>
+#include "Camera.h"
+
+void Camera::Init()
+{
+	m_yaw = 0.0;
+	m_pitch = 0.0;
+
+	SetPos(0, 0, 0);
+}
+
+void Camera::Refresh()
+{
+	// Camera parameter according to Riegl's co-ordinate system
+	// x/y for flat, z for height
+	m_lx = cos(m_yaw) * cos(m_pitch);
+	m_ly = sin(m_pitch);
+	m_lz = sin(m_yaw) * cos(m_pitch);
+
+	m_strafe_lx = cos(m_yaw - M_PI_2);
+	m_strafe_lz = sin(m_yaw - M_PI_2);
+
+	glMatrixMode(GL_MODELVIEW);
+	glLoadIdentity();
+	gluLookAt(m_x, m_y, m_z, m_x + m_lx, m_y + m_ly, m_z + m_lz, 0.0,1.0,0.0);
+
+	printf("Camera: %f %f %f Direction vector: %f %f %f\n", m_x, m_y, m_z, m_lx, m_ly, m_lz);
+}
+
+void Camera::SetPos(float x, float y, float z)
+{
+	m_x = x;
+	m_y = y;
+	m_z =z;
+
+	Refresh();
+}
+
+void Camera::GetPos(float &x, float &y, float &z)
+{
+    x = m_x;
+    y = m_y;
+    z = m_z;
+}
+
+void Camera::GetDirectionVector(float &x, float &y, float &z)
+{
+    x = m_lx;
+    y = m_ly;
+    z = m_lz;
+}
+
+void Camera::Move(float incr)
+{
+    float lx = cos(m_yaw)*cos(m_pitch);
+    float ly = sin(m_pitch);
+    float lz = sin(m_yaw)*cos(m_pitch);
+
+	m_x = m_x + incr*lx;
+	m_y = m_y + incr*ly;
+	m_z = m_z + incr*lz;
+
+	Refresh();
+}
+
+void Camera::Strafe(float incr)
+{
+	m_x = m_x + incr*m_strafe_lx;
+	m_z = m_z + incr*m_strafe_lz;
+
+	Refresh();
+}
+
+void Camera::Fly(float incr)
+{
+	m_y = m_y + incr;
+
+	Refresh();
+}
+
+void Camera::RotateYaw(float angle)
+{
+	m_yaw += angle;
+
+	Refresh();
+}
+
+void Camera::RotatePitch(float angle)
+{
+    const float limit = 89.0 * M_PI / 180.0;
+
+	m_pitch += angle;
+
+    if(m_pitch < -limit)
+        m_pitch = -limit;
+
+    if(m_pitch > limit)
+        m_pitch = limit;
+
+	Refresh();
+}
+
+void Camera::SetYaw(float angle)
+{
+	m_yaw = angle;
+
+	Refresh();
+}
+
+void Camera::SetPitch(float angle)
+{
+    m_pitch = angle;
+
+    Refresh();
+}
diff --git a/camera/Camera.h b/camera/Camera.h
new file mode 100644
index 0000000..8dece1f
--- /dev/null
+++ b/camera/Camera.h
@@ -0,0 +1,36 @@
+#ifndef __CAMERA_H__
+#define __CAMERA_H__
+
+/*
+Generic camera class by Nghia Ho
+*/
+
+class Camera
+{
+public:
+	Camera() { Init(); }
+	~Camera(){}
+
+	void Init();
+	void Refresh();
+	void SetPos(float x, float y, float z);
+    void GetPos(float &x, float &y, float &z);
+    void GetDirectionVector(float &x, float &y, float &z);
+	void SetYaw(float angle);
+	void SetPitch(float angle);
+
+	// Navigation
+	void Move(float incr);
+	void Strafe(float incr);
+	void Fly(float incr);
+	void RotateYaw(float angle);
+	void RotatePitch(float angle);
+
+private:
+	float m_x, m_y, m_z;   // Position
+    float m_lx, m_ly, m_lz; // Direction vector of where we are looking at
+	float m_yaw, m_pitch; // Various rotation angles
+	float m_strafe_lx, m_strafe_lz; // Always 90 degree to direction vector
+};
+
+#endif