From 116a5e3d1a1e5f1c89d8d60d0c8e0f73f7e90005 Mon Sep 17 00:00:00 2001
From: Anselme <anselme.francois@gmail.com>
Date: Tue, 21 Jun 2016 17:15:38 +0200
Subject: [PATCH] added basic camera (default camera implementation)

---
 src/camera.h            | 45 +++++++++++++++++++++++++++-
 src/trackballcamera.cpp | 65 +++++++++++++++++++++++++++++++++++++++++
 src/trackballcamera.h   | 27 +++++++++++++++++
 3 files changed, 136 insertions(+), 1 deletion(-)
 create mode 100644 src/trackballcamera.cpp
 create mode 100644 src/trackballcamera.h

diff --git a/src/camera.h b/src/camera.h
index ca57f0b..ccd2ffb 100644
--- a/src/camera.h
+++ b/src/camera.h
@@ -2,8 +2,10 @@
 #define CAMERA_H
 
 #include <glm/mat4x4.hpp>
+#include <glm/ext.hpp>
 
-class Camera{
+class Camera
+{
 	public:
 		virtual glm::mat4 getProjectionMatrix() = 0;
 		virtual glm::mat4 getViewMatrix() = 0;
@@ -11,4 +13,45 @@ class Camera{
         virtual ~Camera() {}
 };
 
+class BasicCamera : public Camera
+{
+    protected:
+        glm::mat4 m_view;
+        glm::mat4 m_projection;
+    
+        float m_fov;
+        float m_near;
+        float m_far;
+        float m_ratio;
+        
+        void computeProj() { m_projection = glm::perspective(m_fov, m_ratio, m_near, m_far); }
+        
+    public:
+        BasicCamera(float myFov = 70.f, float myNear = 0.1f, float myFar = 100.f) :
+            m_fov(myFov), m_near(myNear), m_far(myFar), m_ratio(1.f)
+        {
+            computeProj();
+            setView(glm::vec3(0), glm::vec3(0, 0, 1));
+        }
+        
+        virtual glm::mat4 getProjectionMatrix() { return m_projection; }
+		virtual glm::mat4 getViewMatrix() { return m_view; }
+		virtual void      resize(int width, int height)
+        {
+            if(width > 0 && height > 0)
+            {
+                m_ratio = float(width)/float(height);
+                computeProj();
+            }
+        }
+        
+        void setFov(float fov = 70.f) { m_fov = fov; computeProj(); }
+        void setNear(float myNear = 0.1f) { m_near = myNear; computeProj(); }
+        void setFar(float myFar = 100.f) { m_far = myFar; computeProj(); }
+        void setView(glm::vec3 cameraPos, glm::vec3 target, glm::vec3 upVector = glm::vec3(0, 1, 0))
+        {
+            m_view = glm::lookAt(cameraPos, target, upVector);
+        }
+};
+
 #endif // CAMERA_H
diff --git a/src/trackballcamera.cpp b/src/trackballcamera.cpp
new file mode 100644
index 0000000..10f276c
--- /dev/null
+++ b/src/trackballcamera.cpp
@@ -0,0 +1,65 @@
+#include "trackballcamera.h"
+#include <glm/ext.hpp>
+
+#define DEFAULT_SCROLL_SPEED 0.998f
+#define DEFAULT_ROTATION_SPEED 0.01f
+#define DEFAULT_MOVE_SPEED 0.002f
+
+TrackBallCamera::TrackBallCamera(float myFov, float myNear, float myFar) :
+    BasicCamera(myFov, myNear, myFar)
+{
+    reset();
+}
+
+void TrackBallCamera::rotateCamera(float dx, float dy)
+{
+    m_rotation.x += dx*DEFAULT_ROTATION_SPEED;
+    m_rotation.y += dy*DEFAULT_ROTATION_SPEED;
+    if(m_rotation.y > 1.57f)
+        m_rotation.y = 1.57f;
+    if(m_rotation.y < -1.57f)
+        m_rotation.y = -1.57f;
+    computeView();
+}
+
+void TrackBallCamera::moveCamera(float dx, float dy)
+{
+        glm::mat4 inverseMVP = glm::inverse(m_projection * m_view);
+        glm::vec4 diff = inverseMVP * glm::vec4(dx*m_dist*DEFAULT_MOVE_SPEED, dy*m_dist*DEFAULT_MOVE_SPEED, 0, 1);
+        m_center += glm::vec3(diff);
+        computeView();
+}
+
+void TrackBallCamera::reset()
+{
+    m_center = glm::vec3(0, 4, 0);
+    m_rotation = glm::vec2(0, 1);
+    m_dist = 20;
+    computeView();
+}
+
+void TrackBallCamera::computeView()
+{
+    m_view = glm::translate(glm::mat4(), glm::vec3(0, 0, -m_dist));
+    m_view = glm::rotate(m_view, m_rotation.y, glm::vec3(1, 0, 0));
+    m_view = glm::rotate(m_view, m_rotation.x, glm::vec3(0, 1, 0));
+    m_view = glm::translate(m_view, -m_center);
+}
+
+void TrackBallCamera::zoom(int nbUnits)
+{
+	while(nbUnits != 0)
+	{
+		if(nbUnits > 0)
+		{
+			m_dist *= DEFAULT_SCROLL_SPEED;
+			--nbUnits;
+		}
+		else
+		{
+			m_dist /= DEFAULT_SCROLL_SPEED;
+			++nbUnits;
+		}
+	}
+	computeView();
+}
diff --git a/src/trackballcamera.h b/src/trackballcamera.h
new file mode 100644
index 0000000..31e67e2
--- /dev/null
+++ b/src/trackballcamera.h
@@ -0,0 +1,27 @@
+#ifndef TRACKBALLCAMERA_H
+#define TRACKBALLCAMERA_H
+
+#include "camera.h"
+#include <glm/vec2.hpp>
+#include <glm/vec3.hpp>
+
+class TrackBallCamera : public BasicCamera
+{
+private:
+    // camera position
+    glm::vec3 m_center;
+    glm::vec2 m_rotation;
+    float m_dist;
+    
+    void computeView();
+    
+public:
+    TrackBallCamera(float myFov = 70.f, float myNear = 0.1f, float myFar = 100.f);
+
+    void rotateCamera(float dx, float dy);
+    void moveCamera(float dx, float dy);
+	void zoom(int nbScrolls);
+    void reset();
+};
+
+#endif // TRACKBALLCAMERA_H