From 5ccf499a04871129cb188f0ab7c376716a87c823 Mon Sep 17 00:00:00 2001
From: Joursoir <chat@joursoir.net>
Date: Fri, 2 Apr 2021 16:09:59 +0000
Subject: add camera subsystem

---
 src/graphics/Camera.cpp | 90 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/graphics/Camera.hpp | 49 +++++++++++++++++++++++++++
 2 files changed, 139 insertions(+)
 create mode 100644 src/graphics/Camera.cpp
 create mode 100644 src/graphics/Camera.hpp

diff --git a/src/graphics/Camera.cpp b/src/graphics/Camera.cpp
new file mode 100644
index 0000000..2058d5e
--- /dev/null
+++ b/src/graphics/Camera.cpp
@@ -0,0 +1,90 @@
+#include <glm/gtc/matrix_transform.hpp>
+
+#include "Camera.hpp"
+using namespace glm;
+
+Camera::Camera(vec3 a_pos, vec3 a_front, vec3 a_up,
+	GLfloat a_yaw, GLfloat a_pitch)
+	: move_speed(init_speed),
+	mouse_sensitivity(init_sensitivity),
+	fov(init_fov)
+{
+	position = a_pos;
+	up = a_up;
+	world_up = up;
+	yaw = a_yaw;
+	pitch = a_pitch;
+	UpdateVectors();
+}
+
+mat4 Camera::GetProjViewMatrix(int w_width, int w_height)
+{
+	return 
+		perspective(fov, (GLfloat)w_width / (GLfloat)w_height, 0.1f, 100.0f) *
+		lookAt(position, position + front, up);
+}
+
+mat4 Camera::GetSkyboxMatrix(int w_width, int w_height)
+{
+	return 
+		perspective(fov, (GLfloat)w_width / (GLfloat)w_height, 0.1f, 100.0f) *
+		mat4(mat3(lookAt(position, position + front, up)));
+}
+
+void Camera::Movement(camera_move direction, GLfloat delta_time)
+{
+	GLfloat velocity;
+	velocity = move_speed * delta_time;
+	switch(direction) {
+	case FORWARD:
+		position += front * velocity;
+		break;
+	case BACKWARD:
+		position -= front * velocity;
+		break;
+	case LEFT:
+		position -= right * velocity;
+		break;
+	case RIGHT:
+		position += right * velocity;
+		break;
+	}
+	UpdateVectors();
+}
+
+void Camera::View(GLfloat delta_x, GLfloat delta_y)
+{
+	yaw += delta_x * mouse_sensitivity;
+	pitch -= delta_y * mouse_sensitivity; // if '+' then inverse
+
+	if(pitch > 89.0f)
+		pitch = 89.0f;
+	else if(pitch < -89.0f)
+		pitch = -89.0f;
+
+	UpdateVectors();
+}
+
+void Camera::Fov(GLfloat delta_y)
+{
+	if(!delta_y)
+		return;
+
+	fov -= radians(delta_y);
+	if(fov > radians(45.0f))
+		fov = radians(45.0f);
+	else if(fov < radians(1.0f))
+		fov = radians(1.0f);
+}
+
+void Camera::UpdateVectors()
+{
+	front.x = cos(radians(yaw)) * cos(radians(pitch));
+	front.y = sin(radians(pitch));
+	front.z = sin(radians(yaw)) * cos(radians(pitch));
+
+	/* Normalize the vectors, because their length gets closer to 0 
+	the more you look up or down which results in slower movement. */
+	right = normalize(cross(front, world_up));
+	up = normalize(cross(right, front));
+}
diff --git a/src/graphics/Camera.hpp b/src/graphics/Camera.hpp
new file mode 100644
index 0000000..6182b5f
--- /dev/null
+++ b/src/graphics/Camera.hpp
@@ -0,0 +1,49 @@
+#ifndef ENGINE_CAMERA_H
+#define ENGINE_CAMERA_H
+
+#include <GL/glew.h>
+#include <glm/glm.hpp>
+
+enum camera_move {
+    FORWARD,
+    BACKWARD,
+    LEFT,
+    RIGHT
+};
+
+const GLfloat
+			init_yaw = -90.0f,
+			init_pitch = 0.0f,
+			init_speed = 2.5f,
+			init_sensitivity = 0.25f,
+			init_fov = glm::radians(45.0f);
+
+class Camera {
+	glm::vec3 position;
+	glm::vec3 front;
+	glm::vec3 up;
+	glm::vec3 right;
+	glm::vec3 world_up;
+
+	GLfloat yaw; // around x
+	GLfloat pitch; // around y
+
+	GLfloat move_speed;
+	GLfloat mouse_sensitivity;
+	GLfloat fov;
+public:
+	Camera(glm::vec3 a_pos = glm::vec3(0.0f, 0.0f, 5.0f),
+		glm::vec3 a_front = glm::vec3(0.0f, 0.0f, -1.0f),
+		glm::vec3 a_up = glm::vec3(0.0f, 1.0f, 0.0f),
+		GLfloat a_yaw = init_yaw, GLfloat a_pitch = init_pitch);
+
+	glm::mat4 GetProjViewMatrix(int w_width, int w_height);
+	glm::mat4 GetSkyboxMatrix(int w_width, int w_height);
+	void Movement(camera_move direction, GLfloat deltaTime);
+	void View(GLfloat delta_x, GLfloat delta_y);
+	void Fov(GLfloat delta_y);
+private:
+	void UpdateVectors();
+};
+
+#endif /* ENGINE_CAMERA_H */
-- 
cgit v1.2.3-18-g5258