http://wenku.baidu.com/link?url=g5MI06Y9wOvMRx36XU7dp6niJth7_3Y8Yv6D8x3ALFLt75R3EEf_lGWLJZL_GAOikRys4DJj9ffT9UDetUOtsCrchQJussFDLKohUe8Qbp_
http://www.cnblogs.com/jay-dong/archive/2012/09/26/2704188.html
上面是对贝塞尔的说明。
有时候绘制曲线,需要用平滑的曲线绘制
这里取得两个控制点是P0,P3的中点P1((x0+x3)/2,y0) P2((x0+x3)/2,y3)
void Widget::Bsaier()
{
polygon.clear();
for(int i = 0; i < 5; i++){
int y1,y2;
float t = 0;
for(int n = 0; n < 100; n++){
float half = (point[i+1].x() - point[i].x())/2.0;
float tmpy = Cal(point[i].y(),point[i].y(),point[i+1].y(),point[i+1].y(),t);
float tmpx = Cal(point[i].x(),point[i].x()+half,point[i].x()+half,point[i+1].x(),t);
polygon<<QPointF(tmpx,tmpy);
qDebug()<<QPoint(tmpx,tmpy);
t+=0.01;
qDebug()<<n;
}
}
}
float Widget::Cal(float y1,float y2,float y3,float y4,float t)
{
float tmpy = y1*(1-t)*(1-t)*(1-t)
+3*y2*t*(1-t)*(1-t)
+3*y3*t*t*(1-t)
+y4*t*t*t;
return tmpy;
}