Implement keyboard camera control

inc/camera.h

@@ -35,6 +35,9 @@ void camera_zoom(camera_t* camera, float amount);
  *  pan if the button was already held down. */
 void camera_set_mouse_pos(camera_t* camera, float x, float y);
 
+/*  Rotates camera's axes by specified amount of degrees. */
+void camera_rotate(camera_t* camera, float x, float y);
+
 /*  Schedules a camera animation to update projection */
 void camera_anim_proj_perspective(camera_t* camera);
 void camera_anim_proj_orthographic(camera_t* camera);

inc/instance.h

@@ -47,4 +47,5 @@ void instance_cb_window_size(instance_t* instance, int width, int height);
 void instance_cb_mouse_pos(instance_t* instance, float xpos, float ypos);
 void instance_cb_mouse_click(instance_t* instance, int button, int action, int mods);
 void instance_cb_mouse_scroll(instance_t* instance, float xoffset, float yoffset);
+void instance_cb_key_press(instance_t* instance, int key, int scancode, int action, int mods);
 void instance_cb_focus(instance_t* instance, bool focus);

src/camera.c

@@ -193,6 +193,29 @@ void camera_set_mouse_pos(camera_t* camera, float x, float y) {
     }
 }
 
+void camera_rotate(camera_t* camera, float x, float y)
+{
+    /*  Update pitch and clamp values */
+    camera->pitch += y / 360.0f * M_PI;
+    if (camera->pitch < -M_PI) {
+        camera->pitch = -M_PI;
+    } else if (camera->pitch > 0.0f) {
+        camera->pitch = 0.0f;
+    }
+
+    /*  Update yaw and keep it under 360 degrees */
+    camera->yaw += x / 360.0f * M_PI;
+    while (camera->yaw < 0.0f) {
+        camera->yaw += 2.0f * M_PI;
+    }
+    while (camera->yaw > 2.0f * M_PI) {
+        camera->yaw -= 2.0f * M_PI;
+    }
+
+    /*  Rebuild view matrix with new values */
+    camera_update_view(camera);
+}
+
 static void camera_set_anim(camera_t* camera, anim_t* anim) {
     if (camera->anim) {
         log_warn("Triggered an animation while another was running; skipping");

src/instance.c

@@ -134,6 +134,27 @@ void instance_cb_mouse_scroll(instance_t* instance,
     camera_zoom(instance->camera, yoffset);
 }
 
+void instance_cb_key_press(instance_t* instance, int key, int scancode,
+                           int action, int mods)
+{
+    (void)scancode;
+    (void)mods;
+    if (action == GLFW_PRESS) {
+        if (key == GLFW_KEY_LEFT || key == GLFW_KEY_RIGHT ||
+            key == GLFW_KEY_UP || key == GLFW_KEY_DOWN) {
+            if (key == GLFW_KEY_LEFT) {
+                camera_rotate(instance->camera, 2.0f, 0.0f);
+            } else if (key == GLFW_KEY_RIGHT) {
+                camera_rotate(instance->camera, -2.0f, 0.0f);
+            } else if (key == GLFW_KEY_UP) {
+                camera_rotate(instance->camera, 0.0f, 2.0f);
+            } else {
+                camera_rotate(instance->camera, 0.0f, -2.0f);
+            }
+        }
+    }
+}
+
 void instance_cb_focus(instance_t* instance, bool focus)
 {
     instance->focused = focus;

src/window.c

@@ -26,6 +26,13 @@ static void cb_mouse_click(GLFWwindow* window, int button,
     instance_cb_mouse_click(instance, button, action, mods);
 }
 
+static void cb_key_press(GLFWwindow* window, const int key, const int scancode,
+                         const int action, const int mods)
+{
+    instance_t* instance = (instance_t*)glfwGetWindowUserPointer(window);
+    instance_cb_key_press(instance, key, scancode, action, mods);
+}
+
 static void cb_drop(GLFWwindow* window, int count, const char** paths)
 {
     instance_t* instance = (instance_t*)glfwGetWindowUserPointer(window);
@@ -59,6 +66,7 @@ void window_bind(GLFWwindow* window, instance_t* instance) {
     glfwSetCursorPosCallback(window, cb_mouse_pos);
     glfwSetScrollCallback(window, cb_mouse_scroll);
     glfwSetMouseButtonCallback(window, cb_mouse_click);
+    glfwSetKeyCallback(window, cb_key_press);
     glfwSetDropCallback(window, cb_drop);
     glfwSetWindowFocusCallback(window, cb_focus);
     glfwSetWindowCloseCallback(window, cb_close);