# coding: utf-8
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"""This module provides a class managing an OpenGL vertex buffer."""
__authors__ = ["T. Vincent"]
__license__ = "MIT"
__date__ = "10/01/2017"
import logging
from ctypes import c_void_p
import numpy
from . import gl
from .utils import numpyToGLType, sizeofGLType
_logger = logging.getLogger(__name__)
[docs]class VertexBuffer(object):
"""Object handling an OpenGL vertex buffer object
:param data: Data used to fill the vertex buffer
:type data: numpy.ndarray or None
:param int size: Size in bytes of the buffer or None for data size
:param usage: OpenGL vertex buffer expected usage pattern:
GL_STREAM_DRAW, GL_STATIC_DRAW (default) or GL_DYNAMIC_DRAW
:param target: Target buffer:
GL_ARRAY_BUFFER (default) or GL_ELEMENT_ARRAY_BUFFER
"""
# OpenGL|ES 2.0 subset:
_USAGES = gl.GL_STREAM_DRAW, gl.GL_STATIC_DRAW, gl.GL_DYNAMIC_DRAW
_TARGETS = gl.GL_ARRAY_BUFFER, gl.GL_ELEMENT_ARRAY_BUFFER
def __init__(self,
data=None,
size=None,
usage=None,
target=None):
if usage is None:
usage = gl.GL_STATIC_DRAW
assert usage in self._USAGES
if target is None:
target = gl.GL_ARRAY_BUFFER
assert target in self._TARGETS
self._target = target
self._usage = usage
self._name = gl.glGenBuffers(1)
self.bind()
if data is None:
assert size is not None
self._size = size
gl.glBufferData(self._target,
self._size,
c_void_p(0),
self._usage)
else:
data = numpy.array(data, copy=False, order='C')
if size is not None:
assert size <= data.nbytes
self._size = size or data.nbytes
gl.glBufferData(self._target,
self._size,
data,
self._usage)
gl.glBindBuffer(self._target, 0)
@property
def target(self):
"""The target buffer of the vertex buffer"""
return self._target
@property
def usage(self):
"""The expected usage of the vertex buffer"""
return self._usage
@property
def name(self):
"""OpenGL Vertex Buffer object name (int)"""
if self._name is not None:
return self._name
else:
raise RuntimeError("No OpenGL buffer resource, \
discard has already been called")
@property
def size(self):
"""Size in bytes of the Vertex Buffer Object (int)"""
if self._size is not None:
return self._size
else:
raise RuntimeError("No OpenGL buffer resource, \
discard has already been called")
[docs] def bind(self):
"""Bind the vertex buffer"""
gl.glBindBuffer(self._target, self.name)
[docs] def update(self, data, offset=0, size=None):
"""Update vertex buffer content.
:param numpy.ndarray data: The data to put in the vertex buffer
:param int offset: Offset in bytes in the buffer where to put the data
:param int size: If provided, size of data to copy
"""
data = numpy.array(data, copy=False, order='C')
if size is None:
size = data.nbytes
assert offset + size <= self.size
with self:
gl.glBufferSubData(self._target, offset, size, data)
[docs] def discard(self):
"""Delete the vertex buffer"""
if self._name is not None:
gl.glDeleteBuffers(self._name)
self._name = None
self._size = None
else:
_logger.warning("Discard has already been called")
# with statement
def __enter__(self):
self.bind()
def __exit__(self, exctype, excvalue, traceback):
gl.glBindBuffer(self._target, 0)
[docs]class VertexBufferAttrib(object):
"""Describes data stored in a vertex buffer
Convenient class to store info for glVertexAttribPointer calls
:param VertexBuffer vbo: The vertex buffer storing the data
:param int type_: The OpenGL type of the data
:param int size: The number of data elements stored in the VBO
:param int dimension: The number of `type_` element(s) in [1, 4]
:param int offset: Start offset of data in the vertex buffer
:param int stride: Data stride in the vertex buffer
"""
_GL_TYPES = gl.GL_UNSIGNED_BYTE, gl.GL_FLOAT, gl.GL_INT
def __init__(self,
vbo,
type_,
size,
dimension=1,
offset=0,
stride=0,
normalization=False):
self.vbo = vbo
assert type_ in self._GL_TYPES
self.type_ = type_
self.size = size
assert 1 <= dimension <= 4
self.dimension = dimension
self.offset = offset
self.stride = stride
self.normalization = bool(normalization)
@property
def itemsize(self):
"""Size in bytes of a vertex buffer element (int)"""
return self.dimension * sizeofGLType(self.type_)
itemSize = itemsize # Backward compatibility
[docs] def setVertexAttrib(self, attribute):
"""Call glVertexAttribPointer with objects information"""
normalization = gl.GL_TRUE if self.normalization else gl.GL_FALSE
with self.vbo:
gl.glVertexAttribPointer(attribute,
self.dimension,
self.type_,
normalization,
self.stride,
c_void_p(self.offset))
def copy(self):
return VertexBufferAttrib(self.vbo,
self.type_,
self.size,
self.dimension,
self.offset,
self.stride,
self.normalization)
[docs]def vertexBuffer(arrays, prefix=None, suffix=None, usage=None):
"""Create a single vertex buffer from multiple 1D or 2D numpy arrays.
It is possible to reserve memory before and after each array in the VBO
:param arrays: Arrays of data to store
:type arrays: Iterable of numpy.ndarray
:param prefix: If given, number of elements to reserve before each array
:type prefix: Iterable of int or None
:param suffix: If given, number of elements to reserve after each array
:type suffix: Iterable of int or None
:param int usage: vertex buffer expected usage or None for default
:returns: List of VertexBufferAttrib objects sharing the same vertex buffer
"""
info = []
vbosize = 0
if prefix is None:
prefix = (0,) * len(arrays)
if suffix is None:
suffix = (0,) * len(arrays)
for data, pre, post in zip(arrays, prefix, suffix):
data = numpy.array(data, copy=False, order='C')
shape = data.shape
assert len(shape) <= 2
type_ = numpyToGLType(data.dtype)
size = shape[0] + pre + post
dimension = 1 if len(shape) == 1 else shape[1]
sizeinbytes = size * dimension * sizeofGLType(type_)
sizeinbytes = 4 * ((sizeinbytes + 3) >> 2) # 4 bytes alignment
copyoffset = vbosize + pre * dimension * sizeofGLType(type_)
info.append((data, type_, size, dimension,
vbosize, sizeinbytes, copyoffset))
vbosize += sizeinbytes
vbo = VertexBuffer(size=vbosize, usage=usage)
result = []
for data, type_, size, dimension, offset, sizeinbytes, copyoffset in info:
copysize = data.shape[0] * dimension * sizeofGLType(type_)
vbo.update(data, offset=copyoffset, size=copysize)
result.append(
VertexBufferAttrib(vbo, type_, size, dimension, offset, 0))
return result
