[Add] Camera modes, for first person/third person.

libbettola/include/bettola/math/vec3.h

@@ -10,4 +10,8 @@ inline Vec3 operator+(const Vec3& a, const Vec3& b) {
   return {a.x + b.x, a.y + b.y, a.z + b.z};
 }
 
+inline Vec3 operator*(const Vec3& v, float scalar) {
+  return { v.x * scalar, v.y * scalar, v.z * scalar };
+}
+
 } /* namespace BettolaMath. */

src/bettola.cpp

@@ -8,6 +8,7 @@
 #include <cstdlib>
 #include <cstdio>
 #include "game/player.h"
+#include "graphics/camera.h"
 
 #include "bettola.h"
 
@@ -18,7 +19,8 @@ const int SCREEN_HEIGHT = 600;
 Bettola::Bettola(void) :
     _is_running(false),
     _window(nullptr),
-    _gl_context(nullptr) {}
+    _gl_context(nullptr),
+    _camera_mode(Camera::CameraMode::FIRST_PERSON) {}
 
 Bettola::~Bettola(void) {
   if(_gl_context) {
@@ -87,6 +89,10 @@ void Bettola::process_events(void) {
         case SDLK_S: _input.down  = true; break;
         case SDLK_A: _input.left  = true; break;
         case SDLK_D: _input.right = true; break;
+        case SDLK_V:
+        _camera_mode = (_camera_mode == Camera::CameraMode::FIRST_PERSON) ?
+                        Camera::CameraMode::THIRD_PERSON :Camera::CameraMode::FIRST_PERSON;
+        break;
       }
     } else if(event.type == SDL_EVENT_KEY_UP) {
       switch(event.key.key) {
@@ -115,7 +121,7 @@ void Bettola::update(double dt) {
 
   /* Update camera to follow the local player. */
   const BettolaMath::Vec3 player_pos = player.get_position();
-  _camera.update(player_pos);
+  _camera.update(player_pos, _camera_mode);
 }
 
 void Bettola::render(void) {

src/bettola.h

@@ -32,5 +32,6 @@ private:
   Renderer _renderer;
   GameClient _game_client;
   Camera _camera;
+  Camera::CameraMode _camera_mode;
   PlayerBase::InputState _input;
 };

src/graphics/camera.cpp

@@ -14,15 +14,20 @@ Camera::Camera(void) :
     _pitch(0.0f),
     _distance(10.0f),
     _mouse_sensitivity(0.1f),
-    _zoom_sensitivity(0.5f) {
+    _zoom_sensitivity(0.5f),
+    _first_person_offset({0.0f, 0.5f, 0.0f}) {
 
   _update_camera_vectors();
 }
 
-void Camera::update(const BettolaMath::Vec3& target_pos) {
+void Camera::update(const BettolaMath::Vec3& target_pos, CameraMode mode) {
+  if(mode == CameraMode::THIRD_PERSON) {
     _position.x = target_pos.x - _front.x * _distance;
     _position.y = target_pos.y - _front.y * _distance;
     _position.z = target_pos.z - _front.z * _distance;
+  } else {
+    _position = target_pos + _first_person_offset + (_front * 0.6f);
+  }
 }
 
 void Camera::process_mouse_movement(float x_offset, float y_offset) {

src/graphics/camera.h

@@ -5,9 +5,15 @@
 
 class Camera {
 public:
+  enum class CameraMode {
+    FIRST_PERSON,
+    THIRD_PERSON
+  };
+
   Camera(void);
 
-  void update(const BettolaMath::Vec3& target_pos);
+  void set_mode(CameraMode mode);
+  void update(const BettolaMath::Vec3& target_pos, CameraMode mode);
   void process_mouse_movement(float x_offset, float y_offset);
   void process_mouse_scroll(float y_offset);
 
@@ -21,6 +27,7 @@ private:
   float _yaw;
   float _pitch;
   float _distance;
+  BettolaMath::Vec3 _first_person_offset;
 
   BettolaMath::Vec3 _position;
   BettolaMath::Vec3 _front;