Buffer with Views

API - Buffer with View classes

class VertexBuffer:

    def __init__( self, data = None, nbytes = None, handle = None ):
        self.handle = handle
        if not self.handle:
            self.handle = glGenBuffers( 1 )

        if data:
            nbytes = data.nbytes

        if nbytes:
            self.allocate( nbytes )
            if data:
                self.bind()
                self.set_data( data )
                self.unbind()

    def dtype_view( self, dtype, offset = None, rows = None ):
        return DtypeVertexBuffer( self, dtype, offset, rows )

    def view( self, nbytes, offset = None, type = None ):
        return Buffer

class VertexBufferView:

    def __init__:
        ...

    def offset:
        ...

    def stride:
        ...

    def type:
        ... ????

    def type_enum:
        ... ???


class DtypeVertexBuffer:

    def __init__:
        ...

    def stride:
        ...

    def offset:
        ...

    def __getitem__( self, name ):
        # return a view from the named property
        ...

API - Complex Buffer

class VertexBuffer:

    def __init__( self,
        data = None,
        nbytes = None, offset = None, stride = None,
        dtype = None, rows = None,
        handle = None
        ):
        if dtype and rows:
            nbytes = dtype.itemsize * rows

        if not handle:
            self.handle = glGenBuffers( 1 )
            if nbytes:
                self.bind()
                self.allocate( nbytes = nbytes )
                self.unbind()

    def view( self,
        nbytes = None, offset = 0, stride = None,
        dtype = None, rows = None
        ):
        return Buffer(
            None,
            nbytes, offset, stride,
            dtype, rows,
            self.handle
            )

    def allocate( self, nbytes = None, dtype = None, rows = None ):
        if dtype and rows:
            nbytes = dtype.itemsize * rows

        # create a new array
        glBufferData( target, nbytes )

    def set_data( self, data, offset = 0 ):
        glBufferSubData( ... )

    def set_XYZ_pointer( self,
        location = None, values_per_vertex = None, glType = None, stride = None, offset = None,
        normalise = False, enable = True,
        shader = None, attribute = None, name = None
        ):
        if shader and attribute and name:
            # get from shader
            ...

        # over-ride shader values with any manually specified
        # set using passed in values
        ...

        # pass to opengl
        glXYZPointer( ... )

Usage

# Set data later
buffer = VertexBuffer()
buffer.set_data(data)

# Construct with data
buffer = VertexBuffer(data)

# Get view of buffer using a different dtype
buffer = VertexBuffer(data)
view = buffer.view(dtype)

# Get named value
# no specific dtype set in data
buffer = VertexBuffer(data)
dtype_buffer = buffer.view(dtype)
position = buffer.name('position')

# Get named value 2
# data dtype has position
data = numpy.array( [...], dtype = [('position', 'float32', (3,),] )
buffer = VertexBuffer(data)
position = buffer['position']


# create with specific dtype
buffer = VertexBuffer(dtype)
buffer.set_data(data)

# create multiple views into buffer
buffer = VertexBuffer(data)
chunk1 = buffer.view(dtype, offset = 0, nbytes = X)
chunk2 = buffer.view(dtype, offset = chunk1.nbytes, nbytes = Y)


# create multiple arrays in buffer
buffer = VertexBuffer( [data1, data2] )
position = buffer['position']
colour = buffer['colour']
other = buffer['other']


# create empty buffer of specific size
# using GL enums for types
buffer = VertexBuffer(rows=100, fields=[('pos', GL_FLOAT, 3), ('color', GL_FLOAT, 4)] )