int32_t pivot_lookat(struct Pivot* pivot, const Vec3f target) {
int32_t result = -1;
Vec4f right_axis = RIGHT_AXIS;
Vec4f up_axis = UP_AXIS;
Vec4f forward_axis = FORWARD_AXIS;
struct Pivot world_pivot;
pivot_combine(pivot->parent, pivot, &world_pivot);
Vec4f target_direction;
vec_sub(target, world_pivot.position, target_direction);
float dot_yaw = vec_dot(target_direction, forward_axis);
Quat rotation = {0};
if( fabs(dot_yaw + 1.0f) < CUTE_EPSILON ) {
// vector a and b point exactly in the opposite direction,
// so it is a 180 degrees turn around the up-axis
Quat rotation = {0};
quat_from_axis_angle(up_axis, PI, rotation);
quat_mul(world_pivot.orientation, rotation, rotation);
} else if( fabs(dot_yaw - (1.0f)) < CUTE_EPSILON ) {
// vector a and b point exactly in the same direction
// so we return the identity quaternion
quat_copy(world_pivot.orientation, rotation);
} else {
// - I look at the target by turning the pivot orientation using only
// yaw and pitch movement
// - I always rotate the pivot from its initial orientation (up and forward
// basis vectors like initialized above), so this does not incrementally
// advance the orientation
quat_identity(rotation);
// - to find the amount of yaw I project the target_direction into the
// up_axis plane, resulting in up_projection which is a vector that
// points from the up_axis plane to the tip of the target_direction
Vec4f up_projection = {0};
vec_mul1f(up_axis, vec_dot(target_direction, up_axis), up_projection);
// - so then by subtracting the up_projection from the target_direction,
// I get a vector lying in the up_axis plane, pointing towards the target
Vec4f yaw_direction = {0};
vec_sub(target_direction, up_projection, yaw_direction);
// - angle between yaw_direction and forward_axis is the amount of yaw we
// need to point the forward_axis toward the target
float yaw = 0.0f;
vec_angle(yaw_direction, forward_axis, &yaw);
log_assert( ! isnan(yaw),
"vec_angle(%f %f %f, %f %f %f, %f);\n",
yaw_direction[0], yaw_direction[1], yaw_direction[2],
forward_axis[0], forward_axis[1], forward_axis[2],
yaw );
// - I have to compute the cross product between yaw_direction and
// forward_axis and use the resulting yaw_axis
Vec4f yaw_axis = {0};
vec_cross(yaw_direction, forward_axis, yaw_axis);
if( vec_nullp(yaw_axis) ) {
vec_copy4f(up_axis, yaw_axis);
}
// - compute the yaw rotation
Quat yaw_rotation = {0};
quat_from_axis_angle(yaw_axis, yaw, yaw_rotation);
// - to compute, just as with the yaw, I want an axis that lies on the plane that
// is spanned in this case by the right_axis, when the camera points toward the
// target
// - I could compute an axis, but I already have a direction vector that points
// toward the target, the yaw_direction, I just have to normalize it to make it
// an axis (and put the result in forward_axis, since it now is the forward_axis
// of the yaw turned camera)
Vec4f yaw_forward_axis = {0};
vec_normalize(yaw_direction, yaw_forward_axis);
// - then use the new forward axis with the old target_direction to compute the angle
// between those
float pitch = 0.0f;
vec_angle(target_direction, yaw_forward_axis, &pitch);
log_assert( ! isnan(pitch),
"vec_angle(%f %f %f, %f %f %f, %f);\n",
target_direction[0], target_direction[1], target_direction[2],
yaw_forward_axis[0], yaw_forward_axis[1], yaw_forward_axis[2],
pitch );
// - and just as in the yaw case we compute an rotation pitch_axis
Vec4f pitch_axis = {0};
vec_cross(target_direction, yaw_forward_axis, pitch_axis);
if( vec_nullp(pitch_axis) ) {
vec_copy4f(right_axis, pitch_axis);
}
// - and finally compute the pitch rotation and combine it with the yaw_rotation
// in the same step
Quat pitch_rotation;
quat_from_axis_angle(pitch_axis, pitch, pitch_rotation);
Quat yaw_pitch_rotation;
quat_mul(yaw_rotation, pitch_rotation, yaw_pitch_rotation);
Quat inverted_orientation = {0};
quat_invert(world_pivot.orientation, inverted_orientation);
// - the int32_t I want to return indicates the cameras 'flip' status, that is, it is
// one when the camera angle was pitched so much that it flipped over and its
// up axis is now pointing downwards
// - to find out if I am flipped over, I compute the flipped up_axis called
// flip_axis and then use the dot product between the flip_axis and up_axis
// to decide if I am flipped
Vec4f flip_axis = {0};
vec_rotate(up_axis, inverted_orientation, flip_axis);
vec_rotate(flip_axis, yaw_pitch_rotation, flip_axis);
float dot_pitch = vec_dot(up_axis, flip_axis);
Vec4f target_axis = {0};
vec_normalize(target_direction, target_axis);
// - check if we are flipped and if we are, set result to 1 meaning we are flipped
// - turn the camera around PI so that we can continue pitching, otherwise we just get
// stuck when trying to flip the camera over
if( dot_pitch < 0.0f ) {
result = 1;
quat_from_axis_angle(target_axis, PI, rotation);
quat_mul(yaw_pitch_rotation, rotation, yaw_pitch_rotation);
}
quat_copy(yaw_pitch_rotation, rotation);
}
if( ! isnan(rotation[0]) &&
! isnan(rotation[1]) &&
! isnan(rotation[2]) &&
! isnan(rotation[3]) )
{
quat_copy(rotation, pivot->orientation);
}
pivot->eye_distance = vec_length(target_direction);
return result;
}
bool arcball_event(struct Arcball* arcball, SDL_Event event) {
static int32_t mouse_down = 0;
static const float rotation_slowness_factor = 0.25f;
static int32_t next_flipped = 0;
// - arcball rotation is performed by dragging the mouse, so I just keep track of when
// a mouse button is pressed and released between calls to this function by setting a
// static variable mouse_down to the button number when a button is pressed and back
// to 0 when that button is released
if( event.type == SDL_MOUSEBUTTONDOWN && mouse_down == 0 ) {
mouse_down = event.button.button;
} else if( event.type == SDL_MOUSEBUTTONUP && mouse_down == event.button.button ) {
arcball->flipped = next_flipped;
mouse_down = 0;
}
if( mouse_down == arcball->translate_button && event.type == SDL_MOUSEMOTION ) {
SDL_MouseMotionEvent mouse = event.motion;
float eye_distance = arcball->camera.pivot.eye_distance;
// - when an mouse motion event occurs, and mouse_down to the translation_button so we compute
// a camera translation
// - the camera should pan around on the x-z-plane, keeping its height and orientation
Quat inverted_orientation = {0};
quat_invert(arcball->camera.pivot.orientation, inverted_orientation);
// - the sideways translation is computed by taking the right_axis and orienting it with
// the cameras orientation, the way I set up the lookat implementation this should always
// result in a vector parallel to the x-z-plane
Vec4f right_axis = RIGHT_AXIS;
vec_rotate4f(right_axis, inverted_orientation, right_axis);
if( mouse.xrel != 0 ) {
// - then we'll just multiply the resulting axis with the mouse x relative movement, inversely
// scaled by how far we are away from what we are looking at (farer means faster, nearer
// means slower), the translation_factor is just a value that felt good when this was implemented
Vec4f x_translation = {0};
vec_mul1f(right_axis, (float)mouse.xrel/arcball->translate_factor*eye_distance, x_translation);
// - finally just add the x_translation to the target and position so that the whole arcball moves
vec_add(arcball->target, x_translation, arcball->target);
vec_add(arcball->camera.pivot.position, x_translation, arcball->camera.pivot.position);
}
// - the z translation can't be done along the orientated forward axis because that would include
// the camera pitch, here, same as above, we need an axis that is parallel to the x-z-plane
Vec4f up_axis = UP_AXIS;
if( mouse.yrel != 0 ) {
// - luckily such an axis is easily computed from the crossproduct of the orientated right_axis and
// the default up_axis, the result is an axis pointing in the direction of the cameras forward axis,
// while still being parallel to the x-z-plane
Vec4f forward_axis;
vec_cross(right_axis, up_axis, forward_axis);
// - same as above
Vec4f z_translation;
vec_mul1f(forward_axis, (float)mouse.yrel/arcball->translate_factor*eye_distance, z_translation);
// - dito
vec_add(arcball->target, z_translation, arcball->target);
vec_add(arcball->camera.pivot.position, z_translation, arcball->camera.pivot.position);
}
} else if( mouse_down == arcball->rotate_button && event.type == SDL_MOUSEMOTION ) {
SDL_MouseMotionEvent mouse = event.motion;
// - above case was translation, this is an rotation occuring: mouse_down is equal to the
// rotation_button and the event is a mouse motion
// - the camera needs to rotate around the target while keeping its height, orientation and
// without _any_ rolling
// - we want only yaw and pitch movement
// - yaw is easy, just use the fixed up_axis and create a rotation the rotates around it
// by the mouse x relative movement (converted to radians)
// - the flipped value indicates if the camera is flipped over, so we'll just use that to
// change the sign of the yaw to make the mouse movement on the screen always correctly
// relates to the movement of the rotation
Vec4f up_axis = UP_AXIS;
Quat yaw_rotation = {0};
quat_from_axis_angle(up_axis, arcball->flipped * PI/180 * mouse.xrel * rotation_slowness_factor, yaw_rotation);
// - pitch is a little more involved, I need to compute the orientated right axis and use
// that to compute the pitch_rotation
Quat inverted_orientation = {0};
quat_invert(arcball->camera.pivot.orientation, inverted_orientation);
Vec4f right_axis = RIGHT_AXIS;
vec_rotate4f(right_axis, inverted_orientation, right_axis);
Quat pitch_rotation = {0};
quat_from_axis_angle(right_axis, -PI/180 * mouse.yrel * rotation_slowness_factor, pitch_rotation);
// - combine yaw and pitch into a single rotation
Quat rotation = {0};
quat_mul(yaw_rotation, pitch_rotation, rotation);
// - orbit is the position translated to the coordinate root
// - the yaw and pitch rotation is applied to the orbit
// - orbit is translated back and replaces the camera position
Vec4f orbit = {0};
vec_sub(arcball->camera.pivot.position, arcball->target, orbit);
vec_rotate4f(orbit, rotation, orbit);
vec_add(arcball->target, orbit, arcball->camera.pivot.position);
// - after updating the position we just call lookat to compute the new
// orientation, and also set the flipped state
next_flipped = pivot_lookat(&arcball->camera.pivot, arcball->target);
}
if( event.type == SDL_MOUSEWHEEL ) {
SDL_MouseWheelEvent wheel = event.wheel;
// - zooming when mouse wheel event happens
float* eye_distance = &arcball->camera.pivot.eye_distance;
if( (*eye_distance > arcball->camera.frustum.z_near || wheel.y < 0) &&
(*eye_distance < arcball->camera.frustum.z_far || wheel.y > 0))
{
// - just going back and forth along the oriented forward axis, using wheel
// y motion inversly scaled by the eye_distance, similar to what is done
// for the translation above (farer == faster zoom, nearer == slower zoom)
Quat inverted_orientation = {0};
quat_invert(arcball->camera.pivot.orientation, inverted_orientation);
Vec4f forward_axis = FORWARD_AXIS;
vec_rotate4f(forward_axis, inverted_orientation, forward_axis);
Vec4f zoom = {0};
vec_mul1f(forward_axis, wheel.y/arcball->zoom_factor*(*eye_distance), zoom);
vec_add(arcball->camera.pivot.position, zoom, arcball->camera.pivot.position);
// - eye_distance is kept in camera state, so we need to update it here
*eye_distance = vlength(arcball->camera.pivot.position);
}
}
return true;
}
int32_t main(int32_t argc, char *argv[]) {
printf("<<watchlist//>>\n");
if( init_sdl2() ) {
return 1;
}
int32_t width = 1280;
int32_t height = 720;
SDL_Window* window;
sdl2_window("cute3d: " __FILE__, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, width, height, &window);
SDL_GLContext* context;
sdl2_glcontext(3, 2, window, &context);
if( init_shader() ) {
return 1;
}
if( init_vbo() ) {
return 1;
}
if( init_canvas(1280,720) ) {
return 1;
}
canvas_create("global_dynamic_canvas", &global_dynamic_canvas);
canvas_create("global_static_canvas", &global_static_canvas);
struct Vbo vbo = {0};
vbo_create(&vbo);
vbo_add_buffer(&vbo, SHADER_ATTRIBUTE_VERTEX, 3, GL_FLOAT, GL_STATIC_DRAW);
vbo_add_buffer(&vbo, SHADER_ATTRIBUTE_VERTEX_NORMAL, 3, GL_FLOAT, GL_STATIC_DRAW);
vbo_add_buffer(&vbo, SHADER_ATTRIBUTE_VERTEX_COLOR, 4, GL_UNSIGNED_BYTE, GL_STATIC_DRAW);
struct Ibo ibo = {0};
ibo_create(GL_TRIANGLES, GL_UNSIGNED_INT, GL_STATIC_DRAW, &ibo);
struct CollisionEntity entity_a = {0};
entity_create("red", (Color){ 255, 0, 0, 255 }, &vbo, &ibo, &entity_a);
/* quat_mul_axis_angle(entity_a.pivot.orientation, (Vec4f)UP_AXIS, PI/4, entity_a.pivot.orientation); */
/* quat_mul_axis_angle(entity_a.pivot.orientation, (Vec4f)RIGHT_AXIS, PI/2 + 0.2, entity_a.pivot.orientation); */
vec_add(entity_a.pivot.position, (Vec4f){0.2, 0.15, 0.8, 1.0}, entity_a.pivot.position);
struct CollisionEntity entity_b = {0};
entity_create("green", (Color){ 0, 255, 0, 255 }, &vbo, &ibo, &entity_b);
quat_mul_axis_angle(entity_b.pivot.orientation, (Vec4f)RIGHT_AXIS, PI/4 - 0.2, entity_b.pivot.orientation);
quat_mul_axis_angle(entity_b.pivot.orientation, (Vec4f)UP_AXIS, PI/2 + 0.0, entity_b.pivot.orientation);
struct Shader flat_shader = {0};
shader_create(&flat_shader);
shader_attach(&flat_shader, GL_VERTEX_SHADER, "prefix.vert", 1, "flat_shading.vert");
shader_attach(&flat_shader, GL_FRAGMENT_SHADER, "prefix.frag", 1, "flat_shading.frag");
shader_make_program(&flat_shader, SHADER_DEFAULT_NAMES, "flat_shader");
Vec4f light_direction = { 0.2, -0.5, -1.0 };
shader_set_uniform_3f(&flat_shader, flat_shader.program, SHADER_UNIFORM_LIGHT_DIRECTION, 3, GL_FLOAT, light_direction);
Color ambiance = { 65, 25, 50, 255 };
shader_set_uniform_4f(&flat_shader, flat_shader.program, SHADER_UNIFORM_AMBIENT_LIGHT, 4, GL_UNSIGNED_BYTE, ambiance);
struct Arcball arcball = {0};
arcball_create(width, height, (Vec4f){5.0, 3.0, 5.0, 1.0}, (Vec4f){0.0, 0.0, 0.0, 1.0}, 1.0, 1000.0, &arcball);
size_t num_entities = 2;
struct PickingSphere* picking_spheres[2];
picking_spheres[0] = &entity_a.picking_sphere;
picking_spheres[1] = &entity_b.picking_sphere;
struct CollisionEntity* picking_entities[2];
picking_entities[0] = &entity_a;
picking_entities[1] = &entity_b;
struct GameTime time = {0};
gametime_create(1.0f / 60.0f, &time);
draw_grid(&global_static_canvas, 0, (Mat)IDENTITY_MAT, (Color){127, 127, 127, 127}, 0.01f, 12.0f, 12.0f, 12);
while (true) {
SDL_Event event;
while( sdl2_poll_event(&event) ) {
if( sdl2_handle_quit(event) ) {
goto done;
}
sdl2_handle_resize(event);
if( picking_sphere_drag_event(&arcball.camera, num_entities, picking_spheres, event) ) {
struct CollisionEntity* selected_entity = NULL;
float nearest = -FLT_MIN;
for( size_t i = 0; i < num_entities; i++ ) {
if( picking_spheres[i]->picked && ( picking_spheres[i]->front < nearest || nearest < 0.0f ) ) {
nearest = picking_spheres[i]->front;
selected_entity = picking_entities[i];
}
}
static int32_t last_x = -1;
static int32_t last_y = -1;
if( selected_entity != NULL ) {
if( last_x > -1 && last_y > -1 ) {
float distance = selected_entity->picking_sphere.front;
Vec4f a = {0};
camera_ray(&arcball.camera, CAMERA_PERSPECTIVE, last_x, last_y, a);
vec_mul1f(a, distance, a);
Vec4f b = {0};
camera_ray(&arcball.camera, CAMERA_PERSPECTIVE, event.motion.x, event.motion.y, b);
vec_mul1f(b, distance, b);
Vec4f move = {0};
vec_sub(b, a, move);
float length = vec_length(move);
move[1] = 0.0f;
vec_normalize(move, move);
vec_mul1f(move, length, move);
vec_add(selected_entity->pivot.position, move, selected_entity->pivot.position);
}
last_x = event.motion.x;
last_y = event.motion.y;
}
if( event.type == SDL_MOUSEBUTTONUP ) {
last_x = -1;
last_y = -1;
}
} else {
arcball_handle_resize(&arcball, event);
arcball_handle_mouse(&arcball, event);
}
}
sdl2_gl_set_swap_interval(0);
gametime_advance(&time, sdl2_time_delta());
ogl_debug( glClearDepth(1.0f);
glClearColor(.0f, .0f, .0f, 1.0f);
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); );
Mat projection_mat = {0};
Mat view_mat = {0};
camera_matrices(&arcball.camera, CAMERA_PERSPECTIVE, projection_mat, view_mat);
Mat identity = {0};
mat_identity(identity);
Mat transform_a = {0};
pivot_world_transform(&entity_a.pivot, transform_a);
//vbo_mesh_render(&entity_a.vbo_mesh, &flat_shader, &arcball.camera, transform_a);
draw_halfedgemesh_wire(&global_dynamic_canvas, 0, transform_a, (Color){255, 0, 0, 255}, 0.02f, &entity_a.hemesh);
Mat transform_b = {0};
pivot_world_transform(&entity_b.pivot, transform_b);
//vbo_mesh_render(&entity_b.vbo_mesh, &flat_shader, &arcball.camera, transform_b);
draw_halfedgemesh_wire(&global_dynamic_canvas, 0, transform_b, (Color){0, 255, 0, 255}, 0.02f, &entity_b.hemesh);
Mat between_transform = {0};
pivot_between_transform(&entity_a.pivot, &entity_b.pivot, between_transform);
Vec3f foo = {0};
mat_mul_vec(between_transform, entity_a.hemesh.vertices.array[0].position, foo);
struct CollisionConvexConvex collision = {0};
struct CollisionParameter collision_parameter = {
.face_tolerance = 0.9,
.edge_tolerance = 0.95,
.absolute_tolerance = 0.025
};
collision_create_convex_convex(&entity_a.hemesh, &entity_a.pivot,
&entity_b.hemesh, &entity_b.pivot,
collision_parameter,
&collision);
if( collision_test_convex_convex(&collision) ) {
collision_contact_convex_convex(&collision);
//printf("//collision: %d\n", collision_counter);
const struct Contacts* contacts = &collision.contacts;
VecP* m = contacts->points[contacts->num_contacts-1];
for( int32_t i = 0; i < contacts->num_contacts; i++ ) {
VecP* n = contacts->points[i];
draw_line(&global_dynamic_canvas, 0, transform_b, (Color){255, 255, 255, 255}, 0.08f, m, n);
m = n;
}
}
gametime_integrate(&time);
Vec4f screen_cursor = {0,0,0,1};
text_show_fps(&global_dynamic_canvas, 0, screen_cursor, 0, 0, (Color){255, 255, 255, 255}, 20.0, "default_font", time.frame);
canvas_render_layers(&global_static_canvas, 0, 0, &arcball.camera, (Mat)IDENTITY_MAT);
canvas_render_layers(&global_dynamic_canvas, 0, 0, &arcball.camera, (Mat)IDENTITY_MAT);
canvas_clear(&global_dynamic_canvas);
sdl2_gl_swap_window(window);
}
done:
SDL_Quit();
printf("done\n");
return 0;
}
