Function ui_button_behavior_depth

StereoKitC/ui/ui_core.cpp:243–285

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void ui_button_behavior_depth(vec3 window_relative_pos, vec2 size, uint64_t id, float button_depth, float button_activation_depth, float &out_finger_offset, button_state_ &out_button_state, button_state_ &out_focus_state, int32_t* out_opt_hand) {
	out_button_state = button_state_inactive;
	out_focus_state  = button_state_inactive;
	int32_t hand     = -1;

	// Button interaction focus is detected out in front of the button to 
	// prevent 'reverse' or 'side' presses where the finger comes from the
	// back or side.
	//
	// Once focused is gained, interaction is tracked within a volume that
	// extends from the detection plane, to a good distance through the
	// button's back. This is to help when the user's finger inevitably goes
	// completely through the button. Width and height is added to this 
	// volume to account for vertical or horizontal movement during a press,
	// such as the downward motion often accompanying a 'poke' motion.
	float activation_plane = button_depth + skui_finger_radius*2;
	vec3  activation_start = window_relative_pos + vec3{ 0, 0, -activation_plane };
	vec3  activation_size  = vec3{ size.x, size.y, 0.0001f };

	vec3  box_size  = vec3{ size.x + 2*skui_finger_radius, size.y + 2*skui_finger_radius, activation_plane + 6*skui_finger_radius  };
	vec3  box_start = window_relative_pos + vec3{ skui_finger_radius, skui_finger_radius, -activation_plane + box_size.z };
	ui_box_interaction_1h_poke(id,
		activation_start, activation_size,
		box_start,        box_size,
		&out_focus_state, &hand);

	// If a hand is interacting, adjust the button surface accordingly
	out_finger_offset = button_depth;
	if (out_focus_state & button_state_active) {
		out_finger_offset = -(skui_hand[hand].finger.z+skui_finger_radius) - window_relative_pos.z;
		bool pressed  = out_finger_offset < button_activation_depth;
		out_button_state  = ui_active_set(hand, id, pressed);
		out_finger_offset = fminf(fmaxf(2*mm2m, out_finger_offset), button_depth);
	} else if (out_focus_state & button_state_just_inactive) {
		out_button_state = ui_active_set(hand, id, false);
	}
	
	if (out_button_state & button_state_just_active)
		ui_play_sound_on_off(ui_vis_button, id, skui_hand[hand].finger_world);

	if (out_opt_hand)
		*out_opt_hand = hand;
}

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