How to send QImage to Qt3D Entity from C++ to QML for using it as texture?

Question

I need to change the texture of a plane in a 3D scene. In the BackEnd class in C++ I make a new QImage for setting it on a texture. I want to send it as a signal to my QML and there assign it to the planes material property.

But it looks like TextureMaterial etc. can only use a URL path to a texture file. I cant't save my Images to my hard drive to use them as a URL path. It will be too long. I need to change my texture 20+ times in a second and there are other things which this program should to do in the same time.

Is there any way to do this?

Answer 1

You can have a look at my implementation of a background image in Qt3D .

The way I achieved what you are looking for is by using the classes QTextureMaterial , QTexture2D and QPaintedTextureImage . I had to flip the image before drawing it that's why I subclassed QPaintedTextureImage but this might also just be what you need. Instead of loading the texture from disk, like I did, you could set the QImage on your subclass as an attribute. You only need to make the C++ class available to QML and set it on your plane (maybe you could even use PaintedTextureImage directly and write the image painting in their JavaScript-style language).

You can add your QPaintedTextureIage to the QTexture2D and then set the result as the texture on the QTextureMaterial . I'm not sure if this yields the best performance, though.

You could also try to follow these steps but they seem to be a bit more involved. This would mean you have to implement your own version of QAbstractTextureImage and return the appropriate QTextureImageDataGeneratorPtr . You can checkout the sources to gain a better understanding.