Source code for arcade.gl.vertex_array

from ctypes import c_void_p, byref
from typing import Dict, Iterable, Optional, Sequence, TYPE_CHECKING
import weakref

from pyglet import gl

from .buffer import Buffer
from .types import BufferDescription
from .program import  Program

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


[docs]class VertexArray: """Wrapper for Vertex Array Objects (VAOs). This objects should not be instantiated from user code. Use :py:class:`arcade.gl.Geometry` instead. It will create VAO instances for you automatically. There is a lot of complex interaction between programs and vertex arrays that will be done for you automatically. """ __slots__ = '_ctx', 'glo', '_program', '_content', '_ibo', '_content', '_num_vertices', '__weakref__' # TODO: Resolve what VertexArray should actually store
[docs] def __init__(self, ctx: 'Context', program: Program, content: Sequence[BufferDescription], index_buffer: Buffer = None): self._ctx = ctx self._program = program self._content = content self.glo = glo = gl.GLuint() self._num_vertices = -1 self._ibo = index_buffer self._build(program, content, index_buffer) self.ctx.stats.incr('vertex_array') weakref.finalize(self, VertexArray.release, self.ctx, glo)
@property def ctx(self) -> 'Context': """ The Context this object belongs to :type: :py:class:`arcade.gl.Context` """ return self._ctx @property def program(self) -> Program: """ The assigned program :type: :py:class:`arcade.gl.Program` """ return self._program @property def ibo(self) -> Optional[Buffer]: """ Element/index buffer :type: :py:class:`arcade.gl.Buffer` """ return self._ibo @property def num_vertices(self) -> int: """ The number of vertices :type: int """ return self._num_vertices
[docs] @staticmethod def release(ctx: 'Context', glo: gl.GLuint): """ Delete this object. This is automatically called when this object is garbage collected. """ # If we have no context, then we are shutting down, so skip this if gl.current_context is None: return if glo.value != 0: gl.glDeleteVertexArrays(1, byref(glo)) glo.value = 0 ctx.stats.decr('vertex_array')
def _build(self, program: Program, content: Sequence[BufferDescription], index_buffer): """Build a vertex array compatible with the program passed in""" gl.glGenVertexArrays(1, byref(self.glo)) gl.glBindVertexArray(self.glo) # Lookup dict for BufferDescription attrib names # print(content) descr_attribs = {attr.name: (descr, attr) for descr in content for attr in descr.formats} # print('->', descr_attribs) # Build the vao according to the shader's attribute specifications for i, prog_attr in enumerate(program.attributes): # print('prog_attr', prog_attr) # Do we actually have an attribute with this name in buffer descriptions? if prog_attr.name.startswith('gl_'): continue try: buff_descr, attr_descr = descr_attribs[prog_attr.name] except KeyError: raise ValueError(( f"Program needs attribute '{prog_attr.name}', but is not present in buffer description. " f"Buffer descriptions: {content}" )) # TODO: Sanity check this # if buff_descr.instanced and i == 0: # raise ValueError("The first vertex attribute cannot be a per instance attribute.") # Make sure components described in BufferDescription and in the shader match if prog_attr.components != attr_descr.components: raise ValueError(( f"Program attribute '{prog_attr.name}' has {prog_attr.components} components " f"while the buffer description has {attr_descr.components} components. " )) # TODO: Compare gltype between buffer descr and program attr gl.glEnableVertexAttribArray(prog_attr.location) gl.glBindBuffer(gl.GL_ARRAY_BUFFER, buff_descr.buffer.glo) # TODO: Detect normalization normalized = gl.GL_TRUE if attr_descr.name in buff_descr.normalized else gl.GL_FALSE gl.glVertexAttribPointer( prog_attr.location, # attrib location attr_descr.components, # 1, 2, 3 or 4 attr_descr.gl_type, # GL_FLOAT etc normalized, # normalize buff_descr.stride, c_void_p(attr_descr.offset), ) # print(( # f"gl.glVertexAttribPointer(\n" # f" {prog_attr.location}, # attrib location\n" # f" {attr_descr.components}, # 1, 2, 3 or 4\n" # f" {attr_descr.gl_type}, # GL_FLOAT etc\n" # f" {normalized}, # normalize\n" # f" {buff_descr.stride},\n" # f" c_void_p({attr_descr.offset}),\n" # )) # TODO: Sanity check this if buff_descr.instanced: gl.glVertexAttribDivisor(prog_attr.location, 1) if index_buffer is not None: gl.glBindBuffer(gl.GL_ELEMENT_ARRAY_BUFFER, index_buffer.glo)
[docs] def render(self, mode: gl.GLenum, first: int = 0, vertices: int = 0, instances: int = 1): """Render the VertexArray to the currently active framebuffer. :param GLuint mode: Primitive type to render. TRIANGLES, LINES etc. :param int first: The first vertex to render from :param int vertices: Number of vertices to render :param int instances: OpenGL instance, used in using vertices over and over """ gl.glBindVertexArray(self.glo) if self._ibo is not None: count = self._ibo.size // 4 # TODO: Support first argument by offsetting pointer (second last arg) gl.glDrawElementsInstanced(mode, count, gl.GL_UNSIGNED_INT, None, instances) else: # print(f"glDrawArraysInstanced({mode}, {first}, {vertices}, {instances})") gl.glDrawArraysInstanced(mode, first, vertices, instances)
[docs] def transform(self, buffer: Buffer, mode: gl.GLenum, output_mode: gl.GLenum, first: int = 0, vertices: int = 0, instances: int = 1, buffer_offset=0): """Run a transform feedback. :param Buffer buffer: The buffer to write the output :param gl.GLenum mode: The input primitive mode :param gl.GLenum output:mode: The output primitive mode :param int first: Offset start vertex :param int vertices: Number of vertices to render :param int instances: Number of instances to render :param int buffer_offset: Byte offset for the buffer """ if vertices < 0: raise ValueError(f"Cannot determine the number of vertices: {vertices}") gl.glBindVertexArray(self.glo) gl.glEnable(gl.GL_RASTERIZER_DISCARD) if buffer_offset > 0: pass else: gl.glBindBufferBase(gl.GL_TRANSFORM_FEEDBACK_BUFFER, buffer_offset, buffer.glo) gl.glBeginTransformFeedback(output_mode) if self._ibo is not None: count = self._ibo.size // 4 # TODO: Support first argument by offsetting pointer (second last arg) gl.glDrawElementsInstanced(mode, count, gl.GL_UNSIGNED_INT, None, instances) else: # print(f"glDrawArraysInstanced({mode}, {first}, {vertices}, {instances})") gl.glDrawArraysInstanced(mode, first, vertices, instances) gl.glEndTransformFeedback() gl.glDisable(gl.GL_RASTERIZER_DISCARD)
[docs]class Geometry: """A higher level abstraction of the VertexArray. It generates VertexArray instances on the fly internally matching the incoming program. This means we can render the same geometry with different programs as long as the :py:class:`~arcade.gl.Program` and :py:class:`~arcade.gl.BufferDescription` have compatible attributes. Geometry objects should be created through :py:meth:`arcade.gl.Context.geometry` :param Contex ctx: The context this object belongs to :param list content: List of BufferDescriptions :param Buffer index_buffer: Index/element buffer :param int mode: The default draw mode """ __slots__ = '_ctx', '_content', '_index_buffer', '_mode', '_vao_cache', '_num_vertices', '__weakref__'
[docs] def __init__( self, ctx: 'Context', content: Optional[Sequence[BufferDescription]], index_buffer: Buffer = None, mode=None): self._ctx = ctx self._content = content or [] self._index_buffer = index_buffer self._mode = mode or ctx.TRIANGLES self._vao_cache = {} # type: Dict[str, VertexArray] self._num_vertices = -1 """ :param Contex ctx: The context this object belongs to :param list content: List of BufferDescriptions :param Buffer index_buffer: Index/element buffer :param int mode: The default draw mode """ # if not content: # raise ValueError("Geometry without buffer descriptions not supported") if content: # Calculate vertices. Use the minimum for now self._num_vertices = content[0].num_vertices for descr in self._content: if descr.instanced: continue self._num_vertices = min(self._num_vertices, descr.num_vertices) # No cleanup is needed, but we want to count them weakref.finalize(self, Geometry._release, self._ctx) self._ctx.stats.incr('geometry')
@property def ctx(self) -> 'Context': """ The context this geometry belongs to. :type: :py:class:`~arcade.gl.Geometry` """ return self._ctx @property def index_buffer(self) -> Optional[Buffer]: """ Index/element buffer if supplied at creation. :type: :py:class:`~arcade.gl.Buffer` """ return self._index_buffer @property def num_vertices(self) -> int: """ Get or set the number of vertices. Be careful when modifying this properly and be absolutely sure what you are doing. :type: int """ # TODO: Calculate this better... return self._num_vertices @num_vertices.setter def num_vertices(self, value: int): self._num_vertices = value
[docs] def instance(self, program: Program) -> VertexArray: """ Get the :py:class:`arcade.gl.VertexArray` compatible with this program """ vao = self._vao_cache.get(program.attribute_key) if vao: return vao return self._generate_vao(program)
[docs] def render(self, program: Program, *, mode: gl.GLenum = None, first: int = 0, vertices: int = None, instances: int = 1) -> None: """Render the geometry with a specific program. :param Program program: The Program to render with :param gl.GLenum mode: Override what primitive mode should be used :param int first: Offset start vertex :param int vertices: Number of vertices to render :param int instances: Number of instances to render """ program.use() vao = self.instance(program) mode = self._mode if mode is None else mode vao.render(mode=mode, first=first, vertices=vertices or self._num_vertices, instances=instances)
[docs] def transform(self, program: Program, buffer: Buffer, *, first: int = 0, vertices: int = None, instances: int = 1, buffer_offset: int = 0) -> None: """Render with transform feedback. Instead of rendering to the screen or a framebuffer the result will instead end up in the ``buffer`` we supply. If a geometry shader is used the output primitive mode is automatically detected. :param Program program: The Program to render with :param Buffer buffer: The buffer to write the output :param gl.GLenum mode: The input primitive mode :param int first: Offset start vertex :param int vertices: Number of vertices to render :param int instances: Number of instances to render :param int buffer_offset: Byte offset for the buffer """ program.use() vao = self.instance(program) # mode = mode if mode is not None else gl.GL_POINTS vao.transform( buffer, mode=program.geometry_input, output_mode=program.geometry_output, first=first, vertices=vertices or self._num_vertices, instances=instances, buffer_offset=buffer_offset, )
[docs] def flush(self) -> None: """ Flush all the internally generated VertexArrays """ self._vao_cache = {}
def _generate_vao(self, program: Program) -> VertexArray: """Here we do the VertexArray building""" # print(f"Generating vao for key {program.attribute_key}") vao = VertexArray(self._ctx, program, self._content, index_buffer=self._index_buffer) self._vao_cache[program.attribute_key] = vao return vao @staticmethod def _release(ctx): """Mainly here to count destroyed instances""" ctx.stats.decr('geometry')