我想用Qt3D创建一个具有自定义图像作为纹理的实体。我遇到了QPaintedTextureImage(链接导致Qt 5.9版本的细节.Here ist doc for 5.8),可以用QPainter编写,但我不明白如何。首先,这就是我想象的实体可能是这样的:
[编辑]:代码已编辑,现在可以使用!
planeEntity = new Qt3DCore::QEntity(rootEntity);
planeMesh = new Qt3DExtras::QPlaneMesh;
planeMesh->setWidth(2);
planeMesh->setHeight(2);
image = new TextureImage; //see below
image->setSize(QSize(100,100));
painter = new QPainter;
image->paint(painter)
planeMaterial = new Qt3DExtras::QDiffuseMapMaterial;
planeMaterial->diffuse()->addTextureImage(image);
planeEntity->addComponent(planeMesh);
planeEntity->addComponent(planeMaterial);
TextureImage是具有绘制功能的子类QPaintedTextureImage:
class TextureImage : public Qt3DRender::QPaintedTextureImage
{
public:
void paint(QPainter* painter);
};
如果我只想在planeEntity中绘制一个大圆圈,那么传递给绘画功能的QPainter需要做什么?
[编辑]实施:
void TextureImage::paint(QPainter* painter)
{
//hardcoded values because there was no device()->width/heigth
painter->fillRect(0, 0, 100, 100, QColor(255, 255, 255));
/* Set pen and brush to whatever you want. */
painter->setPen(QPen(QBrush(QColor(255, 0, 255)) ,10));
painter->setBrush(QColor(0, 0, 255));
/*
* Draw a circle (or an ellipse -- the outcome depends very much on
* the aspect ratio of the bounding rectangle amongst other things).
*/
painter->drawEllipse(0, 0, 100, 100);
}
简短的回答是......使用QPainter
,与通常情况完全相同。
void TextureImage::paint (QPainter* painter)
{
int w = painter->device()->width();
int h = painter->device()->height();
/* Clear to white. */
painter->fillRect(0, 0, w, h, QColor(255, 255, 255));
/* Set pen and brush to whatever you want. */
painter->setPen(QPen(QBrush(QColor(0, 0, 0)) ,10));
painter->setBrush(QColor(0, 0, 255));
/*
* Draw a circle (or an ellipse -- the outcome depends very much on
* the aspect ratio of the bounding rectangle amongst other things).
*/
painter->drawEllipse(0, 0, w, h);
}
但是,请注意,您确实不应该直接调用paint
方法。相反,使用update
将导致Qt安排重绘,初始化QPainter
并使用指向该画家的指针调用重写的paint
方法。
在QML中动态加载所需的图像可能更简单。不久前我不得不这样做,并为此开了一个问题: