QGLSphere Class

Detailed Description

The QGLSphere class represents the geometry of a simple sphere in 3D space.

The following example creates a sphere of 2 units in diameter and draws it at (10, 25, 0) in a QGLPainter:

 QGLBuilder builder;
 builder << QGLSphere(2);
 QGLSceneNode *node = builder.finalizedSceneNode();

 painter.translate(10, 25, 0);
 node->draw(&painter);

The QGLSphere class specifies positions, normals and 2D texture co-ordinates for all of the vertices that make up the sphere.

The texture co-ordinates are fixed at construction time. This is because constructing the sphere can involve generating additional vertices which need to interpolate the texture co-ordinates of their neighboring vertices.

The default mode of QGLSphere is a "UV sphere", which divides the sphere up into longitudinal and latitudinal sections. The longitudinal slices meet at the poles, which in a single unit sphere are defined to be at (0, 0, +0.5) and (0, 0, -0.5). This choice is the simplest to texture map as the texture will only distort along the x-axis of the 2D texture. However the density of vertices is significantly higher at the poles than it is elsewhere on the sphere and is a poor choice if a uniform density of pixels from the texture map is required.