first commit

src/camera.c

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+#include <math.h>
+#include "camera.h"
+
+static bool first_mouse = true;
+static float yaw = -90.0f;
+static float pitch = 0.0f;
+static float last_x = 800.0f / 2.0;
+static float last_y = 600.0f / 2.0;
+static float fov    = 30.0f;
+
+static float delta_time = 0.0f;
+static float last_frame = 0.0f;
+
+static Vector3 camera_pos   = {5, 5, 5};
+static Vector3 camera_front = {-1, -1, -1};
+static Vector3 camera_up    = {0, 1, 0};
+
+Vector3 get_camera_pos(void)
+{
+	return camera_pos;
+}
+
+void rotate_camera(double mouse_x, double mouse_y)
+{
+	float x = mouse_x;
+	float y = mouse_y;
+
+	if (first_mouse) {
+		last_x = x;
+		last_y = y;
+		first_mouse = false;
+	}
+
+	float dx = x - last_x;
+	float dy = last_y - y;
+	last_x = x;
+	last_y = y;
+
+	float sensitivity = 0.1f;
+	dx *= sensitivity;
+	dy *= sensitivity;
+
+	yaw   += dx;
+	pitch += dy;
+
+	if (pitch >  89.0f) pitch =  89.0f;
+	if (pitch < -89.0f) pitch = -89.0f;
+
+	float   yaw_rad = deg2rad(yaw);
+	float pitch_rad = deg2rad(pitch);
+
+	Vector3 front;
+	front.x = cos(yaw_rad) * cos(pitch_rad);
+	front.y = sin(pitch_rad);
+	front.z = sin(yaw_rad) * cos(pitch_rad);
+	front = normalize(front);
+	
+	camera_front = front;
+}
+
+void move_camera(Direction dir, float speed)
+{
+    switch (dir) {
+        case UP   : camera_pos = combine(camera_pos, camera_front, 1, +speed); break;
+        case DOWN : camera_pos = combine(camera_pos, camera_front, 1, -speed); break;
+        case LEFT : camera_pos = combine(camera_pos, normalize(cross(camera_front, camera_up)), 1, -speed); break;
+        case RIGHT: camera_pos = combine(camera_pos, normalize(cross(camera_front, camera_up)), 1, +speed); break;
+    }
+}
+
+Matrix4 camera_pov(void)
+{
+	return lookat_matrix(camera_pos, combine(camera_pos, camera_front, 1, 1), camera_up);
+}
+
+Ray ray_through_screen_at(float px, float py, float aspect_ratio)
+{
+	Vector3 w = normalize(scale(camera_front, -1));
+	Vector3 u = normalize(cross(camera_up, w));
+	Vector3 v = cross(w, u);
+
+	float screen_h = 2 * tan(fov / 2);
+	float screen_w = aspect_ratio * screen_h;
+
+	Vector3 horizontal = scale(u, screen_w);
+	Vector3 vertical   = scale(v, screen_h);
+
+	Vector3 lower_left_corner = combine4(camera_pos, horizontal, vertical, w, 1, -0.5, -0.5, -1);
+
+	Vector3 dir = combine4(lower_left_corner, horizontal, vertical, camera_pos, 1, px, py, -1);
+
+	return (Ray) {.origin=camera_pos, .direction=dir};
+}