我要评论本文实例为大家分享了qpainter画一个3d正的具体代码，供大家参考，具体内容如下
my3dbox .h
#include <eigen/geometry>
using namespace eigen;
#define square_length 200//是一个边长200的正方体
#define camera_distance 300//视点距离
class my3dbox : public qwidget
{
q_object
public:
explicit my3dbox(qwidget *parent = 0);
protected:
qpoint m_mousepos;
vector3d m_vector[8];//正方形8个点坐标
void mousemoveevent(qmouseevent *);
void paintevent(qpaintevent *);
void drawplane(const qpoint *points,qpainter &painter);
matrix3d getmartix();
qpoint topoint(vector3d vector);
void drawup(qpoint *points,qpainter &painter);//正方体面的绘制
void drawdown(qpoint *points,qpainter &painter);
void drawleft(qpoint *points,qpainter &painter);
void drawright(qpoint *points,qpainter &painter);
};
my3dbox .cpp
#include "widget.h"
#define pi 3.1415926
my3dbox::my3dbox(qwidget *parent) :
qwidget(parent),m_mousepos(0,0)
{
setmousetracking(true);//在任何情况下启用mousemoveevent
setgeometry(400,200,500,500);
m_vector[0] << -100,100,100;//设置正方体顶点初始位置
m_vector[1] << 100,100,100;
m_vector[2] << -100,-100,100;
m_vector[3] << 100,-100,100;
m_vector[4] << -100,100,-100;
m_vector[5] << 100,100,-100;
m_vector[6] << -100,-100,-100;
m_vector[7] << 100,-100,-100;
}
void my3dbox::mousemoveevent(qmouseevent *e)//此处把坐标原点从左上角变换至屏幕中心
{
if(e->pos().x() < 0)
m_mousepos.setx(-width()/2);
else if(e->pos().x() > width())
m_mousepos.setx(width()/2);
else
m_mousepos.setx(e->pos().x() - width()/2);
if(e->pos().y() < 0)
m_mousepos.sety(height()/2);
else if(e->pos().y() > height())
m_mousepos.sety(-height()/2);
else
m_mousepos.sety(-e->pos().y() + height()/2);
update();
}
void my3dbox::paintevent(qpaintevent *)
{
qpainter painter(this);
painter.setrenderhint(qpainter::antialiasing);
painter.setrenderhint(qpainter::smoothpixmaptransform);
painter.setpen(qt::nopen);
painter.fillrect(rect(),qcolor(3,22,52));
vector3d vector[8];
matrix3d matrix = getmartix();//获取变换矩阵
qpoint points[8];//正面0123 左面4062 右面1537 上面4501 下面 2367(以观察者的方向为主)
for(int i = 0;i < 8;++i)//计算变换后坐标
{
vector[i] = matrix*m_vector[i];
points[i] = topoint(vector[i]);
points[i].setx(points[i].x()+width()/2);//将坐标系原点变换至左上角
points[i].sety(-points[i].y()+height()/2);
}
//一共要画5个面，最后画正面
if(qabs(m_mousepos.x()) > qabs(m_mousepos.y()))
{
if(m_mousepos.x() > 0)
{
if(m_mousepos.y() > 0)
drawdown(points,painter);
else
drawup(points,painter);
drawleft(points,painter);
}
else
{
if(m_mousepos.y() > 0)
drawdown(points,painter);
else
drawup(points,painter);
drawright(points,painter);
}
}
else
{
if(m_mousepos.y() > 0)
{
if(m_mousepos.x() > 0)
drawleft(points,painter);
else
drawright(points,painter);
drawdown(points,painter);
}
else
{
if(m_mousepos.x() > 0)
drawleft(points,painter);
else
drawright(points,painter);
drawup(points,painter);
}
}
//画正面
qpoint point[4] =
{
points[0],
points[1],
points[3],
points[2]
};
drawplane(point,painter);
}
void my3dbox::drawplane(const qpoint *points,qpainter &painter)
{
qlineargradient lineargradient(points[1],points[3]);//设置渐变色
lineargradient.setcolorat(0.0,qcolor(150,150,250));
lineargradient.setcolorat(1.0,qcolor(170,170,255));
painter.setbrush(qbrush(lineargradient));
painter.drawconvexpolygon(points,4);
}
matrix3d my3dbox::getmartix()
{
double unit_x = 0;//同方向单位向量的x和y
double unit_y = 0;
double z = 0;
if(m_mousepos.x() != 0 || m_mousepos.y() != 0)
{
unit_x = m_mousepos.x()/qsqrt(m_mousepos.x()*m_mousepos.x() + m_mousepos.y()*m_mousepos.y());
unit_y = m_mousepos.y()/qsqrt(m_mousepos.x()*m_mousepos.x() + m_mousepos.y()*m_mousepos.y());
z = qsqrt(m_mousepos.x()*m_mousepos.x() + m_mousepos.y()*m_mousepos.y())/qsqrt(width()*width()/4 + height()*height()/4);
}
matrix3d m_z;
if(unit_x == 0 && unit_y == 0)
m_z << 1,0,0,
0,1,0,
0,0,1;
else
m_z << unit_y,-unit_x,0,
unit_x,unit_y,0,
0,0,1;
matrix3d m_x;
if(z == 0)
m_x << 1,0,0,
0,1,0,
0,0,1;
else
m_x << 1,0,0,
0,cos(z*pi/2.6),sin(z*pi/2.6),
0,-sin(z*pi/2.6),cos(z*pi/2.6);//为什么pi/2大于90度？因为没画背面所以必须小于90度(偷懒)
return m_z.inverse()*m_x*m_z;
}
qpoint my3dbox::topoint(vector3d vector)//将3d坐标投影至平面上
{
qpoint point;
point.setx(camera_distance*vector[0]/(camera_distance-vector[2]));
point.sety(camera_distance*vector[1]/(camera_distance-vector[2]));
return point;
}
void my3dbox::drawup(qpoint *points,qpainter &painter)
{
qpoint point[4] =
{
points[4],
points[5],
points[1],
points[0]
};
drawplane(point,painter);
}
void my3dbox::drawdown(qpoint *points,qpainter &painter)
{
qpoint point[4] =
{
points[2],
points[3],
points[7],
points[6]
};
drawplane(point,painter);
}
void my3dbox::drawleft(qpoint *points,qpainter &painter)
{
qpoint point[4] =
{
points[4],
points[0],
points[2],
points[6]
};
drawplane(point,painter);
}
void my3dbox::drawright(qpoint *points,qpainter &painter)
{
qpoint point[4] =
{
points[1],
points[5],
points[7],
points[3]
};
drawplane(point,painter);
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
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