#include <math.h>
#include "SceneGraphRoot.h"
#include "SGList.h"

// prototype
static void ball_move(SceneGraphPtr node, int screen_w, int screen_h);
static void ball_collision(SceneGraphPtr node, int screen_w, int screen_h);

static float vy = 0.0f; // y 方向速度
static float dt = 1.0/1.0f; // frame rate 

static float e = -0.8f;  // 反発係数
static float g = 9.8f;  // 重力加速度
static float v0 = 0.0f; // 初速は 0

static float h0; // 初期高さ
static float ball_radius = 100.0f;

static void
ball_move_idle(SceneGraphPtr node, int screen_w, int screen_h)
{
}

static void
ball_move(SceneGraphPtr node, int screen_w, int screen_h)
{
    vy += g * dt;
    node->xyz[1] += vy * dt;
}

static void
ball_collision_idle(SceneGraphPtr, int w, int h, SceneGraphPtr tree)
{
}

static void
ball_collision(SceneGraphPtr node, int screen_w, int screen_h,
	       SceneGraphPtr tree)
{
    if (node->xyz[1] > screen_h - ball_radius) {
	node->xyz[1] = screen_h - ball_radius;

	vy *= e;
	if (vy > -g && vy < 0) {
	    vy = 0.0;
	    node->set_move_collision(ball_move_idle, ball_collision_idle);
	}
    }
}


void
ball_bound_init(int screen_w, int screen_h)
{
    SceneGraphPtr ball;

    sgroot->createFromXMLfile("xml_file/Ball.xml");
    ball = sgroot->createSceneGraph(Ball);
    ball->set_move_collision(ball_move, ball_collision);

    h0 = screen_h/2;
    h0 = -1000;

    ball->xyz[0] = screen_w/2;
    ball->xyz[1] = h0;
    ball->xyz[2] = 30.0f;

    sgroot->setSceneData(ball);
}