[PyCUDA] trying to create a 3d texture

[Eli Stevens (Gmail)]

I'm trying to turn a 3d numpy array with float32 data into a texture
that I can read via tex3D inside of kernel code.  I have this in the
kernel:

texture<float, cudaTextureType3D, cudaReadModeElementType> my_tex;

And I have tried both:

    my_texref = cuda_module.get_texref("my_tex")
    my_gpu = pycuda.gpuarray.GPUArray(my_array.shape, numpy.float32)
    my_gpu.set(numpy.array(my_array, order='F'))
    my_gpu.bind_to_texref_ext(my_texref)

and:

    my_texref = cuda_module.get_texref("my_tex")
    my_gpu = pycuda.gpuarray.to_gpu(my_array)
    my_gpu.bind_to_texref_ext(my_texref)

However, all I get from tex3D are zeros.  I suspect that my problem is
conflating "GPUArray" with "Array" - the former being a numpy-like
that does computation on the gpu, while the latter is how one
transfers numpy data to the gpu for use in kernels, etc.  Is that
correct?

I don't see any API support for creating Array instances from
arbitrary (read: 3d) numpy arrays.  Having poked around the source, I
see the source of the function matrix_to_array has the code:

def matrix_to_array(matrix, order, allow_double_hack=False):
    if order.upper() == "C":
        h, w = matrix.shape
        stride = 0
    elif order.upper() == "F":
        w, h = matrix.shape
        stride = -1
    else:
        raise LogicError, "order must be either F or C"

    matrix = np.asarray(matrix, order=order)
    descr = ArrayDescriptor()

    descr.width = w
    descr.height = h

    if matrix.dtype == np.float64 and allow_double_hack:
        descr.format = array_format.SIGNED_INT32
        descr.num_channels = 2
    else:
        descr.format = dtype_to_array_format(matrix.dtype)
        descr.num_channels = 1

    ary = Array(descr)

    copy = Memcpy2D()
    copy.set_src_host(matrix)
    copy.set_dst_array(ary)
    copy.width_in_bytes = copy.src_pitch = copy.dst_pitch = \
            matrix.strides[stride]
    copy.height = h
    copy(aligned=True)

    return ary


Should I be looking to do something similar?  I see there is a
Memcpy3D() in src/wrapper/wrap_cudadrv.cpp - should I be using that?

It seems like the ability to handle 3d numpy arrays should be present
in the pycuda API.  I can produce a patch for a numpy3d_to_array
function if desired.

Thanks for reading,
Eli

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