# Copyright 2017 The dm_control Authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# ============================================================================

"""An OpenGL renderer backed by GLFW."""

from dm_control._render import base

from dm_control._render import executor

# Re-raise any exceptions that occur during module import as `ImportError`s.

# This simplifies the conditional imports in `render/__init__.py`.

try:

import glfw # pylint: disable=g-import-not-at-top

except (ImportError, IOError, OSError) as exc:

raise ImportError from exc

try:

glfw.init()

except glfw.GLFWError as exc:

raise ImportError from exc

class GLFWContext(base.ContextBase):

"""An OpenGL context backed by GLFW."""

def __init__(self, max_width, max_height):

# GLFWContext always uses `PassthroughRenderExecutor` rather than offloading

# rendering calls to a separate thread because GLFW can only be safely used

# from the main thread.

super().__init__(max_width, max_height, executor.PassthroughRenderExecutor)

def _platform_init(self, max_width, max_height):

"""Initializes this context.

Args:

max_width: Integer specifying the maximum framebuffer width in pixels.

max_height: Integer specifying the maximum framebuffer height in pixels.

"""

glfw.window_hint(glfw.VISIBLE, 0)

glfw.window_hint(glfw.DOUBLEBUFFER, 0)

self._context = glfw.create_window(width=max_width, height=max_height,

title='Invisible window', monitor=None,

share=None)

# This reference prevents `glfw.destroy_window` from being garbage-collected

# before the last window is destroyed, otherwise we may get

# `AttributeError`s when the `__del__` method is later called.

self._destroy_window = glfw.destroy_window

def _platform_make_current(self):

glfw.make_context_current(self._context)

def _platform_free(self):

"""Frees resources associated with this context."""

if self._context:

if glfw.get_current_context() == self._context:

glfw.make_context_current(None)

self._destroy_window(self._context)

self._context = None