Source code for

from ctypes import c_int
from contextlib import contextmanager
from typing import Tuple, List, TYPE_CHECKING
import weakref

from pyglet import gl

from .texture import Texture
from .types import pixel_formats

if TYPE_CHECKING:  # handle import cycle caused by type hinting
    from import Context

[docs]class Framebuffer: """ An offscreen render target also called a Framebuffer Object in OpenGL. This implementation is using texture attachments. When creating a Framebuffer we supply it with textures we want our scene rendered into. The advantage of using texture attachments is the ability we get to keep working on the contents of the framebuffer. The best way to create framebuffer is through :py:meth:``:: # Create a 100 x 100 framebuffer with one attachment ctx.framebuffer(color_attachments=[ctx.texture((100, 100), components=4)]) # Create a 100 x 100 framebuffer with two attachments # Shaders can be configured writing to the different layers ctx.framebuffer( color_attachments=[ ctx.texture((100, 100), components=4), ctx.texture((100, 100), components=4), ] ) :param Context ctx: The context this framebuffer belongs to :param List[] color_attachments: List of color attachments. :param depth_attachment: A depth attachment (optional) """ #: Is this the default framebuffer? (window buffer) is_default = False __slots__ = ( "_ctx", "_glo", "_width", "_height", "_color_attachments", "_depth_attachment", "_samples", "_viewport", "_depth_mask", "_draw_buffers", "_prev_fbo", "__weakref__", ) def __init__( self, ctx: "Context", *, color_attachments=None, depth_attachment=None ): self._glo = fbo_id = gl.GLuint() # The OpenGL alias/name self._ctx = ctx if not color_attachments: raise ValueError("Framebuffer must at least have one color attachment") self._color_attachments = ( color_attachments if isinstance(color_attachments, list) else [color_attachments] ) self._depth_attachment = depth_attachment self._samples = 0 # Leaving this at 0 for future sample support self._depth_mask = True # Determines if the depth buffer should be affected self._prev_fbo = None # Create the framebuffer object gl.glGenFramebuffers(1, self._glo) gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, self._glo) # Ensure all attachments have the same size. # OpenGL do actually support different sizes, # but let's keep this simple with high compatibility. self._width, self._height = self._detect_size() self._viewport = 0, 0, self._width, self._height # Attach textures to it for i, tex in enumerate(self._color_attachments): # TODO: Possibly support attaching a specific mipmap level # but we can read from specific mip levels from shaders. gl.glFramebufferTexture2D( gl.GL_FRAMEBUFFER, gl.GL_COLOR_ATTACHMENT0 + i, tex._target, tex.glo, 0, # Level 0 ) if self.depth_attachment: gl.glFramebufferTexture2D( gl.GL_FRAMEBUFFER, gl.GL_DEPTH_ATTACHMENT, self.depth_attachment._target, self.depth_attachment.glo, 0, ) # Ensure the framebuffer is sane! self._check_completeness() # Set up draw buffers. This is simply a prepared list of attachments enums # we use in the use() method to activate the different color attachment layers layers = [ gl.GL_COLOR_ATTACHMENT0 + i for i, _ in enumerate(self._color_attachments) ] # pyglet wants this as a ctypes thingy, so let's prepare it self._draw_buffers = (gl.GLuint * len(layers))(*layers) # Restore the original bound framebuffer to avoid confusion self.ctx.active_framebuffer.use(force=True) if self._ctx.gc_mode == "auto" and not self.is_default: weakref.finalize(self, Framebuffer.delete_glo, ctx, fbo_id) self.ctx.stats.incr("framebuffer") def __del__(self): # Intercept garbage collection if we are using Context.gc() if self._ctx.gc_mode == "context_gc" and not self.is_default and self._glo.value > 0: self._ctx.objects.append(self) @property def glo(self) -> gl.GLuint: """ The OpenGL id/name of the framebuffer :type: GLuint """ return self._glo @property def viewport(self) -> Tuple[int, int, int, int]: """ Get or set the framebuffer's viewport. The viewport parameter are ``(x, y, width, height)``. It determines what part of the framebuffer should be redered to. By default the viewport is ``(0, 0, width, height)``. The viewport value is persistent all will automatically be applies every time the framebuffer is bound. Two or four integer values can be assigned:: # Explicitly set x, y, width, height fb.viewport = 100, 100, 200, 200 # Implies 0, 0, 100, 100 fb.viewport = 100, 100 """ return self._viewport @viewport.setter def viewport(self, value: Tuple[int, int, int, int]): if not isinstance(value, tuple) or len(value) != 4: raise ValueError("viewport should be a 4-component tuple") self._viewport = value # If the framebuffer is bound we need to set the viewport. # Otherwise it will be set on use() if self._ctx.active_framebuffer == self: gl.glViewport(*self._viewport) gl.glScissor(*self._viewport) @property def ctx(self) -> "Context": """ The context this object belongs to. :type: :py:class:`` """ return self._ctx @property def width(self) -> int: """ The width of the framebuffer in pixels :type: int """ return self._width @property def height(self) -> int: """ The height of the framebuffer in pixels :type: int """ return self._height @property def size(self) -> Tuple[int, int]: """ Size as a ``(w, h)`` tuple :type: tuple (int, int) """ return self._width, self._height @property def samples(self) -> int: """ Number of samples (MSAA) :type: int """ return self._samples @property def color_attachments(self) -> List[Texture]: """ A list of color attachments :type: list of :py:class:`` """ return self._color_attachments @property def depth_attachment(self) -> Texture: """ Depth attachment :type: :py:class:`` """ return self._depth_attachment @property def depth_mask(self) -> bool: """ Get or set the depth mask (default: ``True``). It determines if depth values should be written to the depth texture when depth testing is enabled. The depth mask value is persistent all will automatically be applies every time the framebuffer is bound. :type: bool """ return self._depth_mask @depth_mask.setter def depth_mask(self, value: bool): self._depth_mask = value # Set state if framebuffer is active if self._ctx.active_framebuffer == self: gl.glDepthMask(self._depth_mask) def __enter__(self): self._prev_fbo = self._ctx.active_framebuffer self.use() return self def __exit__(self, exc_type, exc_val, exc_tb): self._prev_fbo.use()
[docs] @contextmanager def activate(self): """Context manager for binding the framebuffer. Unlike the default context manager in this class this support nested framebuffer binding. """ prev_fbo = self._ctx.active_framebuffer try: self.use() yield self finally: prev_fbo.use()
[docs] def use(self, *, force: bool = False): """Bind the framebuffer making it the target of all redering commands :param bool force: Force the framebuffer binding even if the system already believes it's already bound. """ self._use(force=force) self._ctx.active_framebuffer = self
def _use(self, *, force: bool = False): """Internal use that do not change the global active framebuffer""" if self.ctx.active_framebuffer == self and not force: return gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, self._glo) # NOTE: gl.glDrawBuffer(GL_NONE) if no texture attachments (future) # NOTE: Default framebuffer currently has this set to None if self._draw_buffers: gl.glDrawBuffers(len(self._draw_buffers), self._draw_buffers) gl.glDepthMask(self._depth_mask) gl.glViewport(*self._viewport) gl.glScissor(*self._viewport)
[docs] def clear( self, color=(0.0, 0.0, 0.0, 0.0), *, depth: float = 1.0, normalized: bool = False, ): """ Clears the framebuffer:: # Clear framebuffer using the color red in normalized form fbo.clear(color=(1.0, 0.0, 0.0, 1.0), normalized=True) # Clear the framebuffer using arcade's colors (not normalized) fb.clear(color=arcade.color.WHITE) If the background color is an ``RGB`` value instead of ``RGBA``` we assume alpha value 255. :param tuple color: A 3 or 4 component tuple containing the color :param float depth: Value to clear the depth buffer (unused) :param bool normalized: If the color values are normalized or not """ with self.activate(): if normalized: # If the colors are already normalized we can pass them right in if len(color) == 3: gl.glClearColor(*color, 1.0) else: gl.glClearColor(*color) else: # OpenGL wants normalized colors (0.0 -> 1.0) if len(color) == 3: gl.glClearColor(color[0] / 255, color[1] / 255, color[2] / 255, 1.0) else: gl.glClearColor( color[0] / 255, color[1] / 255, color[2] / 255, color[3] / 255 ) if self.depth_attachment: gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT) else: gl.glClear(gl.GL_COLOR_BUFFER_BIT)
[docs] def read( self, *, viewport=None, components=3, attachment=0, dtype="f1" ) -> bytearray: """ Read framebuffer pixels :param viewport Tuple[int,int,int,int]: The x, y, with, height to read :param int attachment: The attachment id to read from :param str dtype: The data type to read :return: pixel data as a bytearray """ # TODO: use texture attachment info to determine read format? try: frmt = pixel_formats[dtype] base_format = frmt[0][components] pixel_type = frmt[2] except Exception: raise ValueError(f"Invalid dtype '{dtype}'") with self: # Configure attachment to read from # gl.glReadBuffer(gl.GL_COLOR_ATTACHMENT0 + attachment) if viewport: x, y, width, height = viewport else: x, y, width, height = 0, 0, self._width, self._height data = (gl.GLubyte * (components * width * height))(0) gl.glReadPixels(x, y, width, height, base_format, pixel_type, data) return bytearray(data)
[docs] def resize(self): """ Detects size changes in attachments. This will reset the viewport to ``0, 0, width, height``. """ self._width, self._height = self._detect_size() self.viewport = 0, 0, self.width, self._height
[docs] def delete(self): """ Destroy the underlying OpenGL resource. Don't use this unless you know exactly what you are doing. """ Framebuffer.delete_glo(self._ctx, self._glo) self._glo.value = 0
[docs] @staticmethod def delete_glo(ctx, framebuffer_id): """ Destroys the framebuffer object :param ctx: OpenGL context :param framebuffer_id: Framebuffer to destroy (glo) """ if gl.current_context is None: return gl.glDeleteFramebuffers(1, framebuffer_id) ctx.stats.decr("framebuffer")
def _detect_size(self) -> Tuple[int, int]: """Detect the size of the framebuffer based on the attachments""" expected_size = ( self._color_attachments[0] if self._color_attachments else self._depth_attachment ).size for layer in [*self._color_attachments, self._depth_attachment]: if layer and layer.size != expected_size: raise ValueError( "All framebuffer attachments should have the same size" ) return expected_size @staticmethod def _check_completeness() -> None: """ Checks the completeness of the framebuffer. If the framebuffer is not complete, we cannot continue. """ # See completness rules : states = { gl.GL_FRAMEBUFFER_UNSUPPORTED: "Framebuffer unsupported. Try another format.", gl.GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT: "Framebuffer incomplete attachment.", gl.GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: "Framebuffer missing attachment.", gl.GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT: "Framebuffer unsupported dimension.", gl.GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT: "Framebuffer incomplete formats.", gl.GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER: "Framebuffer incomplete draw buffer.", gl.GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER: "Framebuffer incomplete read buffer.", gl.GL_FRAMEBUFFER_COMPLETE: "Framebuffer is complete.", } status = gl.glCheckFramebufferStatus(gl.GL_FRAMEBUFFER) if status != gl.GL_FRAMEBUFFER_COMPLETE: raise ValueError( "Framebuffer is incomplete. {}".format( states.get(status, "Unknown error") ) ) def __repr__(self): return "<Framebuffer glo={}>".format(self._glo.value)
[docs]class DefaultFrameBuffer(Framebuffer): """Represents the default framebuffer""" #: Is this the default framebuffer? (window buffer) is_default = True __slots__ = () def __init__(self, ctx: "Context"): """Detect the default framebuffer""" self._ctx = ctx # TODO: Can we query this? self._samples = 0 # TODO: Maybe we should map renderbuffers? self._color_attachments = [] self._depth_attachment = None self._depth_mask = True value = c_int() gl.glGetIntegerv(gl.GL_DRAW_FRAMEBUFFER_BINDING, value) self._glo = gl.GLuint(value.value) # Query draw buffers. This will most likely return GL_BACK # value = c_int() # gl.glGetIntegerv(gl.GL_DRAW_BUFFER0, value) # print(value.value) # 1029 GL_BACK 0x405 # self._draw_buffers = (gl.GLuint * 1)(value.value) # NOTE: Don't query for now self._draw_buffers = None # Query viewport values by inspecting the scissor box values = (c_int * 4)() gl.glGetIntegerv(gl.GL_SCISSOR_BOX, values) x, y, width, height = list(values) self._viewport = x, y, width, height self._width = width self._height = height # HACK: Signal the default framebuffer having depth buffer self._depth_attachment = True