static void camOrbit(int dx, int dy)
{
const double radius = 200;
double dist;
Vec3 v = cam_position;
Quaternion o = cam_orientation;
Quaternion q, q2;
/* We invert the transformation because we are transforming the camera
* and not the scene. */
q = quat_conjugate(quat_trackball(dx, dy, radius));
/* The quaternion q gives us an intrinsic transformation, close to unity.
* To make it extrinsic, we compute q2 = o * q * ~o */
q2 = quat_multiply(o, quat_multiply(q, quat_conjugate(o)));
q2 = quat_normalize(q2);
/* As round-off errors accumulate, the distance between the camera and the
* target would normally fluctuate. We take steps to prevent that here. */
dist = vec3_length(v);
v = quat_transform(q2, v);
v = vec3_normalize(v);
v = vec3_scale(v, dist);
cam_position = v;
cam_orientation = quat_multiply(q2, cam_orientation);
}
Vec3 kepler_position_at_E(KeplerOrbit *orbit, double E)
{
double e = orbit->Ecc;
double a = orbit->SMa, b = a * sqrt(1 - e*e);
Vec3 plane_pos;
plane_pos.x = a * (cos(E) - e);
plane_pos.y = b * sin(E);
plane_pos.z = 0;
return quat_transform(orbit->plane_orientation, plane_pos);
}
Vec3 kepler_position_at_true_anomaly(KeplerOrbit *orbit, double theta)
{
double e = orbit->Ecc;
double p = orbit->SMa * (1-e*e);
Vec3 plane_pos;
plane_pos.x = p / (1 + e*cos(theta)) * cos(theta);
plane_pos.y = p / (1 + e*cos(theta)) * sin(theta);
plane_pos.z = 0;
return quat_transform(orbit->plane_orientation, plane_pos);
}
bool handle_input(ALLEGRO_EVENT_QUEUE *ev_queue, Camera *cam)
{
ALLEGRO_EVENT ev;
ALLEGRO_MOUSE_STATE state;
while (al_get_next_event(ev_queue, &ev))
{
switch (ev.type)
{
case ALLEGRO_EVENT_DISPLAY_CLOSE:
return false;
break;
case ALLEGRO_EVENT_MOUSE_BUTTON_UP:
//al_show_mouse_cursor(dpy);
//al_ungrab_mouse();
break;
case ALLEGRO_EVENT_MOUSE_BUTTON_DOWN:
//al_hide_mouse_cursor(dpy);
//al_grab_mouse(dpy);
break;
case ALLEGRO_EVENT_MOUSE_AXES:
if (ev.mouse.dz != 0)
cam_dolly(cam, ev.mouse.dz);
al_get_mouse_state(&state);
/* The y coordinate needs to be inverted because OpenGL has
* the origin in the lower-left and Allegro the upper-left */
if (state.buttons & 1)
cam_orbit(cam, ev.mouse.dx, -ev.mouse.dy);
else if (state.buttons & 2)
cam_rotate(cam, ev.mouse.dx, -ev.mouse.dy);
break;
case ALLEGRO_EVENT_KEY_CHAR:
if (ev.keyboard.unichar == 'w')
{
wireframe = !wireframe;
if (wireframe)
{
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glDisable(GL_CULL_FACE);
}
else
{
glPolygonMode(GL_FRONT, GL_FILL);
glEnable(GL_CULL_FACE);
}
} else if (ev.keyboard.unichar == 'c')
{
Vec3 upv = quat_transform(cam->orientation, (Vec3){0, 1, 0});
cam_lookat(cam, cam->position, cam->target, upv);
}
break;
case ALLEGRO_EVENT_DISPLAY_RESIZE:
cam->width = ev.display.width;
cam->height = ev.display.height;
glmLoadIdentity(glmProjectionMatrix);
cam_projection_matrix(cam, glmProjectionMatrix);
glViewport(cam->left, cam->bottom, cam->width, cam->height);
default:
break;
}
}
return true;
}