Harald — I filed a few bug tickets with example code for some of these issues, as noted below.
- Randy > On Aug 9, 2015, at 11:35 PM, Harald Vistnes <harald.vist...@gmail.com> wrote: > > Hi, > > I have played with the tech preview of Qt3D 2.0 and I have some questions and > wishes. > > 1. Transparency. It does not seem like Qt3D handles transparency at all. For > instance, phong.frag always returns alpha=1.0. I would expect materials like > Qt3D::QPhongMaterial to have an opacity parameter and that the renderer would > first render opaque meshes and then transparent meshes sorted by depth. > Ideally I would love to have support for OIT out of the box, but that may be > too specialized. Will there be any support for transparent materials in the > upcoming release? This requires extra transparency-specific shader code and alpha blending logic, so that is presumably why it is not supported by default. But hopefully the next release will include these kinds of transparency cases: https://bugreports.qt.io/browse/QTBUG-47445 https://bugreports.qt.io/browse/QTBUG-47446 > 2. Shared vertex buffers. How can multiple meshes share the same vertex > buffer? > > 3. Updating vertex buffers. How can one update the vertices of an existing > mesh? Qt3D::QAbstractMesh only expose the meshFunctor() function, so I don't > see how to update an existing mesh with new vertex data. there is an update() method on the abstract mesh, which sends a property update signal for the mesh functor or something like that. > 4. Text. It would be nice with an example showing how to add text to a Qt3D > scene. Both 2D (specified in screen coordinates) and 3D (specified in world > coordinates). I'm only using C++, so that is what is of interest to me. https://bugreports.qt.io/browse/QTBUG-19234 This is probably not super efficient but it does work: renders text to a QImage and uses that for a texture. Using the transparent version of the texture you just get the 2D text floating in space. Uses 3D coordinates, but renders text to a plane. > 5. It would be nice to have a class like QTriangleMesh out of the box where > the user can specify his own vertices, normals, indices, etc. I implemented > such a class following the pattern of the Qt3D::QCylinderMesh implementation, > but ended up with a copy of the vertex/index arrays in both the > TriangleMeshPrivate and TriangleMeshFunctor class before they were actually > used in the Qt3D::QAbstractMeshFunctor::operator()(). Is there a better way > to handle this, to avoid all those copies of the data? I wrote a TriangleStripSet class that has float vectors for vertices and normals, and for per-vertex colors, and an int vector for indexes — it was fairly straightforward but uses non-Qt dynamic vector classes so not directly sharable. It also uses the primitive reset index technique so you can easily restart the triangle strips: https://bugreports.qt.io/browse/QTBUG-47291 > 6. Polygon offset to handle z-fighting. > > 7. All examples in C++. In the tech preview, many of the examples were QML > only. > > Thanks. I'm looking forward to see the progress in the next release! > > Best regards > Harald Vistnes > > _______________________________________________ > Development mailing list > Development@qt-project.org > http://lists.qt-project.org/mailman/listinfo/development _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
