小行星程序使用间接绘制，glMultiDrawArraysIndirect 不渲染和绘制空白
asteroids program using indirect draws, glMultiDrawArraysIndirect not rendering and drawing blank
我正在移植一个程序来学习 Superbible OpenGL 第 7 版中的间接绘制。该程序应该每秒渲染近 10 亿个顶点，并且不会因使用 glMultiDrawArraysIndirect 的现代 opengl 技术而导致提交绘制命令的速度出现瓶颈 任何帮助将不胜感激。谢谢。
这是预期的输出：
更新：我非常感谢 Rabbid76 回答的精彩帮助。代码非常好，关于为什么令人耳目一新和惊人的洞察力。太感谢了！该程序正在按预期显示小行星带！
间接绘制似乎使程序运行得更快。
我同意似乎没有在 python 中将枚举用作 class。另外最好不要。
依赖文件：asteroids_support.zip zip
中有更新的 sbmloader
asteroids.py
的源代码
#!/usr/bin/python3
import sys
import time
import ctypes
fullscreen = True
sys.path.append("./shared")
from sbmloader import SBMObject # location of sbm file format loader
from sbmath import m3dDegToRad, m3dRadToDeg, m3dTranslateMatrix44, m3dRotationMatrix44, m3dMultiply, m3dOrtho, m3dPerspective, rotation_matrix, translate, m3dScaleMatrix44, \
scale, m3dLookAt, normalize
try:
from OpenGL.GLUT import *
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.raw.GL.ARB.vertex_array_object import glGenVertexArrays, glBindVertexArray
except:
print ('''
ERROR: PyOpenGL not installed properly.
''')
sys.exit()
from array import array
from enum import Enum
import numpy as np
from math import cos, sin
identityMatrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]
render_program = GLuint(0)
myobject = SBMObject()
indirect_draw_buffer = GLuint(0)
draw_index_buffer = GLuint(0)
class uniforms():
time = GLint(0)
view_matrix = GLint(0)
proj_matrix = GLint(0)
viewproj_matrix = GLint(0)
uniform = uniforms()
mode = 1
MODE_MULTIDRAW = 1
MODE_SEPARATE_DRAWS = 2
paused = False
vsync = False
NUM_DRAWS = 50000
class DrawArraysIndirectCommand:
count = GLuint(0)
primCount = GLuint(0)
first = GLuint(0)
baseInstance = GLuint(0)
def shader_load(filename, shader_type):
result = GLuint(0)
with open ( filename, "rb") as data:
result = glCreateShader(shader_type)
glShaderSource(result, data.read() )
glCompileShader(result)
return result
def link_from_shaders(shaders, shader_count, delete_shaders, check_errors=False):
program = GLuint(0)
program = glCreateProgram()
for i in range(0, shader_count):
glAttachShader(program, shaders[i]);
glLinkProgram(program);
if (delete_shaders):
for i in range(0, shader_count):
glDeleteShader(shaders[i]);
return program
def load_shaders():
global render_program
global uniform
shaders = [GLuint(0), GLuint(0)]
shaders[0] = shader_load("render.vs.glsl", GL_VERTEX_SHADER)
shaders[1] = shader_load("render.fs.glsl", GL_FRAGMENT_SHADER)
if (render_program):
glDeleteProgram(render_program)
render_program = link_from_shaders(shaders, 2, True)
uniform.time = glGetUniformLocation(render_program, "time")
uniform.view_matrix = glGetUniformLocation(render_program, "view_matrix")
uniform.proj_matrix = glGetUniformLocation(render_program, "proj_matrix")
uniform.viewproj_matrix = glGetUniformLocation(render_program, "viewproj_matrix")
class Scene:
def __init__(self, width, height):
global myobject
global indirect_draw_buffer
global draw_index_buffer
i=0
load_shaders()
myobject.load("asteroids.sbm")
sizeOfDrawIndCmd = ctypes.sizeof(GLuint*4)
glGenBuffers(1, indirect_draw_buffer)
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, indirect_draw_buffer)
glBufferData(GL_DRAW_INDIRECT_BUFFER,
NUM_DRAWS * sizeOfDrawIndCmd,
None,
GL_STATIC_DRAW)
cmd_memory = glMapBufferRange(GL_DRAW_INDIRECT_BUFFER,
0,
NUM_DRAWS * sizeOfDrawIndCmd,
GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
cmd_buffer = ((GLuint * 4) * NUM_DRAWS).from_address(cmd_memory)
for i in range(0, NUM_DRAWS):
first, count = myobject.get_sub_object_info(i % myobject.get_sub_object_count())
cmd_buffer[i][0] = count
cmd_buffer[i][1] = 1
cmd_buffer[i][2] = first
cmd_buffer[i][3] = i
glUnmapBuffer(GL_DRAW_INDIRECT_BUFFER)
glBindVertexArray(myobject.get_vao())
glGenBuffers(1, draw_index_buffer)
glBindBuffer(GL_ARRAY_BUFFER, draw_index_buffer)
glBufferData(GL_ARRAY_BUFFER,
NUM_DRAWS * ctypes.sizeof(GLuint),
None,
GL_STATIC_DRAW)
draw_index = glMapBufferRange(GL_ARRAY_BUFFER,
0,
NUM_DRAWS * ctypes.sizeof(GLuint),
GL_MAP_WRITE_BIT |
GL_MAP_INVALIDATE_BUFFER_BIT)
int_array = (GLuint * NUM_DRAWS).from_address(draw_index)
for i in range(0, NUM_DRAWS):
int_array[i] = i
glUnmapBuffer(GL_ARRAY_BUFFER)
glVertexAttribIPointer(10, 1, GL_UNSIGNED_INT, 0, None)
glVertexAttribDivisor(10, 1)
glEnableVertexAttribArray(10)
glEnable(GL_DEPTH_TEST)
glDepthFunc(GL_LEQUAL)
glEnable(GL_CULL_FACE)
def display(self):
global myobject
currentTime = time.time()
j=0
one = 1.0;
black = [ 0.0, 0.0, 0.0, 0.0 ]
last_time = 0.0;
total_time = 0.0;
if (paused == False):
total_time += (currentTime - last_time)
last_time = currentTime
t = float(total_time)
i = int(total_time * 3.0)
glViewport(0, 0, self.width, self.height)
glClearBufferfv(GL_COLOR, 0, black)
glClearBufferfv(GL_DEPTH, 0, one)
view_matrix = (GLfloat * 16)(*identityMatrix)
view_matrix = m3dLookAt([100.0 * cos(t * 0.023), 100.0 * cos(t * 0.023), 300.0 * sin(t * 0.037) - 600.0],
[0.0, 0.0, 260.0],
normalize([0.1 - cos(t * 0.1) * 0.3, 1.0, 0.0]))
proj_matrix = (GLfloat * 16)(*identityMatrix)
proj_matrix = m3dPerspective(m3dDegToRad(50.0), float(self.width) / float(self.height), 1.0, 2000.0)
glUseProgram(render_program)
glUniform1f(uniform.time, t)
glUniformMatrix4fv(uniform.view_matrix, 1, GL_FALSE, view_matrix)
glUniformMatrix4fv(uniform.proj_matrix, 1, GL_FALSE, proj_matrix)
glUniformMatrix4fv(uniform.viewproj_matrix, 1, GL_FALSE, m3dMultiply(proj_matrix , view_matrix))
glBindVertexArray(myobject.get_vao());
if (mode == MODE_MULTIDRAW):
glMultiDrawArraysIndirect(GL_TRIANGLES, None, NUM_DRAWS, 0);
elif (mode == MODE_SEPARATE_DRAWS):
for j in range(0, NUM_DRAWS):
first, count = myobject.get_sub_object_info(j % myobject.get_sub_object_count())
glDrawArraysInstancedBaseInstance(GL_TRIANGLES,
first,
count,
1, j)
glutSwapBuffers()
def reshape(self, width, height):
self.width = width
self.height = height
def keyboard(self, key, x, y ):
global fullscreen
global paused
global mode
global vsync
print ('key:' , key)
if key == b'\x1b': # ESC
sys.exit()
elif key == b'f' or key == b'F': #fullscreen toggle
if (fullscreen == True):
glutReshapeWindow(512, 512)
glutPositionWindow(int((1360/2)-(512/2)), int((768/2)-(512/2)))
fullscreen = False
else:
glutFullScreen()
fullscreen = True
elif key == b'p' or key == b'P': #fullscreen toggle
paused = not paused # a toggle technique
elif key == b'v' or key == b'V': #fullscreen toggle
vsync = not vsync # a toggle technique
#setVsync(vsync)
elif key == b'd' or key == b'D': #fullscreen toggle
mode += 1
if (mode > 2):
mode = 1
print('done')
def init(self):
pass
def timer(self, blah):
glutPostRedisplay()
glutTimerFunc( int(1/60), self.timer, 0)
time.sleep(1/60.0)
if __name__ == '__main__':
start = time.time()
glutInit()
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(512, 512)
w1 = glutCreateWindow('OpenGL SuperBible - Asteroids')
glutInitWindowPosition(int((1360/2)-(512/2)), int((768/2)-(512/2)))
fullscreen = False
many_cubes = False
#glutFullScreen()
scene = Scene(512,512)
glutReshapeFunc(scene.reshape)
glutDisplayFunc(scene.display)
glutKeyboardFunc(scene.keyboard)
glutIdleFunc(scene.display)
#glutTimerFunc( int(1/60), scene.timer, 0)
scene.init()
glutMainLoop()
移植程序来源：multidrawindirect.cpp
python 函数和方法的参数不是 in-out 参数，它们只是输入。但是您可以 return 来自函数的元组。在classSBMObject:
中更改方法.get_sub_object_info()
class SBMObject:
def get_sub_object_info(self, index):
if (index >= len(sub_object)):
return 0, 0
return sub_object[index].first, sub_object[index].count
并这样称呼它：
first, count = myobject.get_sub_object_info(j % myobject.get_sub_object_count())
如果你想创建一个像下面的 C++ 结构的 16 字节结构
typedef struct {
uint count;
uint instanceCount;
uint first;
uint baseInstance;
} DrawArraysIndirectCommand;
那你就不能用这样的pythonclass
class DrawArraysIndirectCommand:
count = GLuint(0)
primCount = GLuint(0)
first = GLuint(0)
baseInstance = GLuint(0)
This is something completely different in the internal structure and memory layout.
Further note, that [`sys.getsizeof()`](https://docs.python.org/3/library/sys.html) is not the same as [`ctypes.sizeof()`](https://docs.python.org/3/library/ctypes.html). You can vereify this with ease by:
```py
print(sys.getsizeof(GLuint))
print(ctypes.sizeof(GLuint))
"DrawArraysIndirectCommand" 的 16 字节元素可以由 GLuint*4 生成，其大小为：
sizeOfDrawIndCmd = ctypes.sizeof(GLuint*4)
glMapBufferRange returns a pointer to a allocated memory region, "wrap" a 2 dimensional array toby using the ctypes function .from_address().
参见 。
sizeOfDrawIndCmd = ctypes.sizeof(GLuint*4)
glGenBuffers(1, indirect_draw_buffer)
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, indirect_draw_buffer)
glBufferData(GL_DRAW_INDIRECT_BUFFER,
NUM_DRAWS * sizeOfDrawIndCmd,
None,
GL_STATIC_DRAW)
cmd_memory = glMapBufferRange(GL_DRAW_INDIRECT_BUFFER,
0,
NUM_DRAWS * sizeOfDrawIndCmd,
GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
cmd_buffer = ((GLuint * 4) * NUM_DRAWS).from_address(cmd_memory)
for i in range(0, NUM_DRAWS):
first, count = myobject.get_sub_object_info(i % myobject.get_sub_object_count())
cmd_buffer[i][0] = count
cmd_buffer[i][1] = 1
cmd_buffer[i][2] = first
cmd_buffer[i][3] = i
glUnmapBuffer(GL_DRAW_INDIRECT_BUFFER)
属性具有整型数据类型 (GL_UNSIGNED_INT)。您必须创建一个格式正确的缓冲区。类型必须是 GLuint（或 ctypes.c_uint）而不是 ctypes.c_float:
int_array = ((ctypes.c_float ) * NUM_DRAWS).from_address(draw_index)
int_array = (GLuint * NUM_DRAWS).from_address(draw_index)
并使用 ctypes.sizeof(GLuint) 而不是 sys.getsizeof(GLuint):
glGenBuffers(1, draw_index_buffer)
glBindBuffer(GL_ARRAY_BUFFER, draw_index_buffer)
glBufferData(GL_ARRAY_BUFFER,
NUM_DRAWS * ctypes.sizeof(GLuint),
None,
GL_STATIC_DRAW)
draw_index = glMapBufferRange(GL_ARRAY_BUFFER,
0,
NUM_DRAWS * ctypes.sizeof(GLuint),
GL_MAP_WRITE_BIT |
GL_MAP_INVALIDATE_BUFFER_BIT)
int_array = (GLuint * NUM_DRAWS).from_address(draw_index)
for i in range(0, NUM_DRAWS):
int_array[i] = i
glUnmapBuffer(GL_ARRAY_BUFFER)
我正在移植一个程序来学习 Superbible OpenGL 第 7 版中的间接绘制。该程序应该每秒渲染近 10 亿个顶点，并且不会因使用 glMultiDrawArraysIndirect 的现代 opengl 技术而导致提交绘制命令的速度出现瓶颈 任何帮助将不胜感激。谢谢。
这是预期的输出：
更新：我非常感谢 Rabbid76 回答的精彩帮助。代码非常好，关于为什么令人耳目一新和惊人的洞察力。太感谢了！该程序正在按预期显示小行星带！
间接绘制似乎使程序运行得更快。
我同意似乎没有在 python 中将枚举用作 class。另外最好不要。
依赖文件：asteroids_support.zip zip
中有更新的 sbmloaderasteroids.py
的源代码#!/usr/bin/python3
import sys
import time
import ctypes
fullscreen = True
sys.path.append("./shared")
from sbmloader import SBMObject # location of sbm file format loader
from sbmath import m3dDegToRad, m3dRadToDeg, m3dTranslateMatrix44, m3dRotationMatrix44, m3dMultiply, m3dOrtho, m3dPerspective, rotation_matrix, translate, m3dScaleMatrix44, \
scale, m3dLookAt, normalize
try:
from OpenGL.GLUT import *
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.raw.GL.ARB.vertex_array_object import glGenVertexArrays, glBindVertexArray
except:
print ('''
ERROR: PyOpenGL not installed properly.
''')
sys.exit()
from array import array
from enum import Enum
import numpy as np
from math import cos, sin
identityMatrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]
render_program = GLuint(0)
myobject = SBMObject()
indirect_draw_buffer = GLuint(0)
draw_index_buffer = GLuint(0)
class uniforms():
time = GLint(0)
view_matrix = GLint(0)
proj_matrix = GLint(0)
viewproj_matrix = GLint(0)
uniform = uniforms()
mode = 1
MODE_MULTIDRAW = 1
MODE_SEPARATE_DRAWS = 2
paused = False
vsync = False
NUM_DRAWS = 50000
class DrawArraysIndirectCommand:
count = GLuint(0)
primCount = GLuint(0)
first = GLuint(0)
baseInstance = GLuint(0)
def shader_load(filename, shader_type):
result = GLuint(0)
with open ( filename, "rb") as data:
result = glCreateShader(shader_type)
glShaderSource(result, data.read() )
glCompileShader(result)
return result
def link_from_shaders(shaders, shader_count, delete_shaders, check_errors=False):
program = GLuint(0)
program = glCreateProgram()
for i in range(0, shader_count):
glAttachShader(program, shaders[i]);
glLinkProgram(program);
if (delete_shaders):
for i in range(0, shader_count):
glDeleteShader(shaders[i]);
return program
def load_shaders():
global render_program
global uniform
shaders = [GLuint(0), GLuint(0)]
shaders[0] = shader_load("render.vs.glsl", GL_VERTEX_SHADER)
shaders[1] = shader_load("render.fs.glsl", GL_FRAGMENT_SHADER)
if (render_program):
glDeleteProgram(render_program)
render_program = link_from_shaders(shaders, 2, True)
uniform.time = glGetUniformLocation(render_program, "time")
uniform.view_matrix = glGetUniformLocation(render_program, "view_matrix")
uniform.proj_matrix = glGetUniformLocation(render_program, "proj_matrix")
uniform.viewproj_matrix = glGetUniformLocation(render_program, "viewproj_matrix")
class Scene:
def __init__(self, width, height):
global myobject
global indirect_draw_buffer
global draw_index_buffer
i=0
load_shaders()
myobject.load("asteroids.sbm")
sizeOfDrawIndCmd = ctypes.sizeof(GLuint*4)
glGenBuffers(1, indirect_draw_buffer)
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, indirect_draw_buffer)
glBufferData(GL_DRAW_INDIRECT_BUFFER,
NUM_DRAWS * sizeOfDrawIndCmd,
None,
GL_STATIC_DRAW)
cmd_memory = glMapBufferRange(GL_DRAW_INDIRECT_BUFFER,
0,
NUM_DRAWS * sizeOfDrawIndCmd,
GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
cmd_buffer = ((GLuint * 4) * NUM_DRAWS).from_address(cmd_memory)
for i in range(0, NUM_DRAWS):
first, count = myobject.get_sub_object_info(i % myobject.get_sub_object_count())
cmd_buffer[i][0] = count
cmd_buffer[i][1] = 1
cmd_buffer[i][2] = first
cmd_buffer[i][3] = i
glUnmapBuffer(GL_DRAW_INDIRECT_BUFFER)
glBindVertexArray(myobject.get_vao())
glGenBuffers(1, draw_index_buffer)
glBindBuffer(GL_ARRAY_BUFFER, draw_index_buffer)
glBufferData(GL_ARRAY_BUFFER,
NUM_DRAWS * ctypes.sizeof(GLuint),
None,
GL_STATIC_DRAW)
draw_index = glMapBufferRange(GL_ARRAY_BUFFER,
0,
NUM_DRAWS * ctypes.sizeof(GLuint),
GL_MAP_WRITE_BIT |
GL_MAP_INVALIDATE_BUFFER_BIT)
int_array = (GLuint * NUM_DRAWS).from_address(draw_index)
for i in range(0, NUM_DRAWS):
int_array[i] = i
glUnmapBuffer(GL_ARRAY_BUFFER)
glVertexAttribIPointer(10, 1, GL_UNSIGNED_INT, 0, None)
glVertexAttribDivisor(10, 1)
glEnableVertexAttribArray(10)
glEnable(GL_DEPTH_TEST)
glDepthFunc(GL_LEQUAL)
glEnable(GL_CULL_FACE)
def display(self):
global myobject
currentTime = time.time()
j=0
one = 1.0;
black = [ 0.0, 0.0, 0.0, 0.0 ]
last_time = 0.0;
total_time = 0.0;
if (paused == False):
total_time += (currentTime - last_time)
last_time = currentTime
t = float(total_time)
i = int(total_time * 3.0)
glViewport(0, 0, self.width, self.height)
glClearBufferfv(GL_COLOR, 0, black)
glClearBufferfv(GL_DEPTH, 0, one)
view_matrix = (GLfloat * 16)(*identityMatrix)
view_matrix = m3dLookAt([100.0 * cos(t * 0.023), 100.0 * cos(t * 0.023), 300.0 * sin(t * 0.037) - 600.0],
[0.0, 0.0, 260.0],
normalize([0.1 - cos(t * 0.1) * 0.3, 1.0, 0.0]))
proj_matrix = (GLfloat * 16)(*identityMatrix)
proj_matrix = m3dPerspective(m3dDegToRad(50.0), float(self.width) / float(self.height), 1.0, 2000.0)
glUseProgram(render_program)
glUniform1f(uniform.time, t)
glUniformMatrix4fv(uniform.view_matrix, 1, GL_FALSE, view_matrix)
glUniformMatrix4fv(uniform.proj_matrix, 1, GL_FALSE, proj_matrix)
glUniformMatrix4fv(uniform.viewproj_matrix, 1, GL_FALSE, m3dMultiply(proj_matrix , view_matrix))
glBindVertexArray(myobject.get_vao());
if (mode == MODE_MULTIDRAW):
glMultiDrawArraysIndirect(GL_TRIANGLES, None, NUM_DRAWS, 0);
elif (mode == MODE_SEPARATE_DRAWS):
for j in range(0, NUM_DRAWS):
first, count = myobject.get_sub_object_info(j % myobject.get_sub_object_count())
glDrawArraysInstancedBaseInstance(GL_TRIANGLES,
first,
count,
1, j)
glutSwapBuffers()
def reshape(self, width, height):
self.width = width
self.height = height
def keyboard(self, key, x, y ):
global fullscreen
global paused
global mode
global vsync
print ('key:' , key)
if key == b'\x1b': # ESC
sys.exit()
elif key == b'f' or key == b'F': #fullscreen toggle
if (fullscreen == True):
glutReshapeWindow(512, 512)
glutPositionWindow(int((1360/2)-(512/2)), int((768/2)-(512/2)))
fullscreen = False
else:
glutFullScreen()
fullscreen = True
elif key == b'p' or key == b'P': #fullscreen toggle
paused = not paused # a toggle technique
elif key == b'v' or key == b'V': #fullscreen toggle
vsync = not vsync # a toggle technique
#setVsync(vsync)
elif key == b'd' or key == b'D': #fullscreen toggle
mode += 1
if (mode > 2):
mode = 1
print('done')
def init(self):
pass
def timer(self, blah):
glutPostRedisplay()
glutTimerFunc( int(1/60), self.timer, 0)
time.sleep(1/60.0)
if __name__ == '__main__':
start = time.time()
glutInit()
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(512, 512)
w1 = glutCreateWindow('OpenGL SuperBible - Asteroids')
glutInitWindowPosition(int((1360/2)-(512/2)), int((768/2)-(512/2)))
fullscreen = False
many_cubes = False
#glutFullScreen()
scene = Scene(512,512)
glutReshapeFunc(scene.reshape)
glutDisplayFunc(scene.display)
glutKeyboardFunc(scene.keyboard)
glutIdleFunc(scene.display)
#glutTimerFunc( int(1/60), scene.timer, 0)
scene.init()
glutMainLoop()
移植程序来源：multidrawindirect.cpp
python 函数和方法的参数不是 in-out 参数，它们只是输入。但是您可以 return 来自函数的元组。在classSBMObject:
.get_sub_object_info()
class SBMObject:
def get_sub_object_info(self, index):
if (index >= len(sub_object)):
return 0, 0
return sub_object[index].first, sub_object[index].count
并这样称呼它：
first, count = myobject.get_sub_object_info(j % myobject.get_sub_object_count())
如果你想创建一个像下面的 C++ 结构的 16 字节结构
typedef struct { uint count; uint instanceCount; uint first; uint baseInstance; } DrawArraysIndirectCommand;
那你就不能用这样的pythonclass
class DrawArraysIndirectCommand: count = GLuint(0) primCount = GLuint(0) first = GLuint(0) baseInstance = GLuint(0)
This is something completely different in the internal structure and memory layout.
Further note, that [`sys.getsizeof()`](https://docs.python.org/3/library/sys.html) is not the same as [`ctypes.sizeof()`](https://docs.python.org/3/library/ctypes.html). You can vereify this with ease by:
```py
print(sys.getsizeof(GLuint))
print(ctypes.sizeof(GLuint))
"DrawArraysIndirectCommand" 的 16 字节元素可以由 GLuint*4 生成，其大小为：
sizeOfDrawIndCmd = ctypes.sizeof(GLuint*4)
glMapBufferRange returns a pointer to a allocated memory region, "wrap" a 2 dimensional array toby using the ctypes function .from_address().
参见
sizeOfDrawIndCmd = ctypes.sizeof(GLuint*4)
glGenBuffers(1, indirect_draw_buffer)
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, indirect_draw_buffer)
glBufferData(GL_DRAW_INDIRECT_BUFFER,
NUM_DRAWS * sizeOfDrawIndCmd,
None,
GL_STATIC_DRAW)
cmd_memory = glMapBufferRange(GL_DRAW_INDIRECT_BUFFER,
0,
NUM_DRAWS * sizeOfDrawIndCmd,
GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
cmd_buffer = ((GLuint * 4) * NUM_DRAWS).from_address(cmd_memory)
for i in range(0, NUM_DRAWS):
first, count = myobject.get_sub_object_info(i % myobject.get_sub_object_count())
cmd_buffer[i][0] = count
cmd_buffer[i][1] = 1
cmd_buffer[i][2] = first
cmd_buffer[i][3] = i
glUnmapBuffer(GL_DRAW_INDIRECT_BUFFER)
属性具有整型数据类型 (GL_UNSIGNED_INT)。您必须创建一个格式正确的缓冲区。类型必须是 GLuint（或 ctypes.c_uint）而不是 ctypes.c_float:
int_array = ((ctypes.c_float ) * NUM_DRAWS).from_address(draw_index)
int_array = (GLuint * NUM_DRAWS).from_address(draw_index)
并使用 ctypes.sizeof(GLuint) 而不是 sys.getsizeof(GLuint):
glGenBuffers(1, draw_index_buffer)
glBindBuffer(GL_ARRAY_BUFFER, draw_index_buffer)
glBufferData(GL_ARRAY_BUFFER,
NUM_DRAWS * ctypes.sizeof(GLuint),
None,
GL_STATIC_DRAW)
draw_index = glMapBufferRange(GL_ARRAY_BUFFER,
0,
NUM_DRAWS * ctypes.sizeof(GLuint),
GL_MAP_WRITE_BIT |
GL_MAP_INVALIDATE_BUFFER_BIT)
int_array = (GLuint * NUM_DRAWS).from_address(draw_index)
for i in range(0, NUM_DRAWS):
int_array[i] = i
glUnmapBuffer(GL_ARRAY_BUFFER)