is there any convenient and effective algorithm
how to draw a ball
In 2D, you just write a pixel shader that clip the pixel when the distance to the center is larger than the radius.
For soft edges, you can also take saturate(radius + 0.5 - distanceToCenter) as opacity from the alpha channel.
For googling you might want to also try "sphere" instead of ball.
It appears directx has a built in function for generating a sphere mesh which you can find and look into.
If it lacks features you need, there are other approaches:
1. Generate the sphere yourself
*Use a kind of longitude/latitude sphere made out of quads. It will cause them to be really tightly packed at the poles.
*Tessellate something like an icosahedron to create spheres of different polygonal fidelity. This will make symmetric spheres where the triangles are not packed around the poles...
*Tessellate a cube and move the corners closer to the center (or extrude the centers of the quads). This might be nice if you want a sphere with 1 texture on each side (the axis directions, so 6 sides)
2. Use a modeling program to create the sphere and import it (probably makes it easier to add texture coords and other data on the vertices)
If you are interested in doing the drawing yourself, you can check out the implementation in my GeometryActor class from Hieroglyph 3.
LPD3DXMESH sphere;Create sphere:
D3DXCreateSphere(device, reduis, slices, stacks, &sphere);
Draw sphere:
device->SetTexture(...);
device->SetMaterial(...);
device->SetTransform(...);
sphere->DrawSubset(0);
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