标签：style blog http io os strong sp div 2014
bool FrameFunc()
{
float dt = hge->Timer_GetDelta();
static float t = 0.0f;
float tx, ty;
int id;
static int lastid = 0;
// If ESCAPE was pressed, tell the GUI to finish
if (hge->Input_GetKeyState(HGEK_ESCAPE)) { lastid = 5; gui->Leave(); }
// We update the GUI and take an action if
// one of the menu items was selected
id = gui->Update(dt);
if (id == -1)
{
switch (lastid)
{
case 1:
case 2:
case 3:
case 4:
gui->SetFocus(1);
gui->Enter();
break;
case 5: return true;
}
}
else if (id) { lastid = id; gui->Leave(); }
// Here we update our background animation
t += dt;
tx = 50 * cosf(t / 60);
ty = 50 * sinf(t / 60);
quad.v[0].tx = tx; quad.v[0].ty = ty;
quad.v[1].tx = tx + 800 / 64; quad.v[1].ty = ty;
quad.v[2].tx = tx + 800 / 64; quad.v[2].ty = ty + 600 / 64;
quad.v[3].tx = tx; quad.v[3].ty = ty + 600 / 64;
return false;
}
在这个代码中，当gui->update(dt)之后，会进行动画的操作。关于gui->update(dt):
If one of the controls has changed it‘s state, Update returns that control‘s identificator. If leave method was called and all the controls have finished their animation, Update returns -1. Otherwise it returns 0.
按照这个解释，我们会遇到三种情况：
1）、指向了某个选项，但是没有选择，那么 return 0;
2）、指向并选择了某个选项，那么 return id; 之后会调用leave();然后选项会消失在屏幕上
3）、在2）之后的情况，调用leave()之后会立刻的 return -1。那么在return -1则会默认指向某个选项，并且会刷新使得选项出现。
将原来的if-else if改成了if-else if-else输出了当前指示的选项。
标签：style blog http io os strong sp div 2014
原文地址：http://www.cnblogs.com/yoru/p/4028246.html
