运行 使用 opengl 函数 glBeginTransformFeedback 进入路障
running into roadblock with opengl function glBeginTransformFeedback
所以我在使用 opengl 函数时遇到了问题 glBeginTransformFeedback 当我取消对这些行的注释时，发生了错误。它说 1282 invalid operation 虽然很含糊。
我的问题是应该如何处理源代码以取消注释这三行：
#glBeginTransformFeedback(GL_POINTS)
#glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
#glEndTransformFeedback()
一个更广泛的问题是关于如何让它正确呈现的任何建议？
更新：在 Rabbid76 优秀代码的帮助下，程序现在可以运行了！！！非常感谢！
成功!!!!当前输出与预期输出相同：
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
import glm
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()
POSITION_A = 0
POSITION_B = 1
VELOCITY_A = 2
VELOCITY_B = 3
CONNECTION = 4
POINTS_X = 50
POINTS_Y = 50
POINTS_TOTAL = POINTS_X * POINTS_Y
CONNECTIONS_TOTAL = (POINTS_X - 1) * POINTS_Y + (POINTS_Y - 1) * POINTS_X
m_vao = [GLuint(0) for _ in range(2)]
m_vbo = [GLuint(0) for _ in range(5)]
m_index_buffer = GLuint(0)
m_pos_tbo = [GLuint(0), GLuint(0)]
m_update_program = GLuint(0)
m_render_program = GLuint(0)
m_C_loc = GLuint(0)
m_iteration_index = 0
draw_points = True
draw_lines = True
iterations_per_frame = 16
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 load_shaders():
global m_update_program
global m_render_program
vs = GLuint(0)
fs = GLuint(0)
buffer = ''
vs = shader_load("update.vs.glsl", GL_VERTEX_SHADER)
if (m_update_program):
glDeleteProgram(m_update_program)
m_update_program = glCreateProgram()
glAttachShader(m_update_program, vs)
# static const char * tf_varyings[] =
# {
# "tf_position_mass",
# "tf_velocity"
# }
# tricky to convert string array to string pointer
tf_varyings = ["tf_position_mass", "tf_velocity"]
# Prepare ctypes data containing the list tf_varyings of strings
array_type = ctypes.c_char_p * len(tf_varyings)
buff = array_type()
for i, e in enumerate(tf_varyings):
buff[i] = e.encode()
# ctypes.c_char
tf_varyings_chrpp = ctypes.cast(ctypes.pointer(buff), ctypes.POINTER(ctypes.POINTER(GLchar)))
glTransformFeedbackVaryings(m_update_program, 2, tf_varyings_chrpp, GL_SEPARATE_ATTRIBS)
glLinkProgram(m_update_program)
glGetShaderInfoLog(vs)
glGetProgramInfoLog(m_update_program)
glDeleteShader(vs)
vs = shader_load("render.vs.glsl", GL_VERTEX_SHADER)
fs = shader_load("render.fs.glsl", GL_FRAGMENT_SHADER)
if (m_render_program):
glDeleteProgram(m_render_program)
m_render_program = glCreateProgram()
glAttachShader(m_render_program, vs)
glAttachShader(m_render_program, fs)
glLinkProgram(m_render_program)
class Scene:
def __init__(self, width, height):
global m_vao
global m_vbo
i = 0
j = 0
load_shaders()
initial_positions = [glm.vec4() for _ in range(POINTS_TOTAL)]
initial_velocities = [glm.vec3() for _ in range(POINTS_TOTAL)]
connection_vectors = [glm.ivec3() for _ in range(POINTS_TOTAL)]
n=0
for j in range(0, POINTS_Y):
fj = float(j) / float(POINTS_Y)
for i in range(0, POINTS_X):
fi = float(i) / float(POINTS_X)
initial_positions[n] = glm.vec4((fi - 0.5) * float(POINTS_X), (fj - 0.5) * float(POINTS_Y), 0.6 * sin(fi) * cos(fj), 1.0)
initial_velocities[n] = glm.vec3(0.0)
connection_vectors[n] = glm.ivec4(-1)
if (j != (POINTS_Y - 1)):
if (i != 0):
connection_vectors[n][0] = n - 1
if (j != 0):
connection_vectors[n][1] = n - POINTS_X
if (i != (POINTS_X - 1)):
connection_vectors[n][2] = n + 1
if (j != (POINTS_Y - 1)):
connection_vectors[n][3] = n + POINTS_X
n+=1
for i in range(0, 2):
glGenVertexArrays(1, m_vao[i])
for i in range(0, 5):
glGenBuffers(i+1, m_vbo[i])
for i in range(0, 2):
glBindVertexArray(m_vao[i])
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[POSITION_A + i])
# POSITION_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[POSITION_A + i])
ar_position = np.empty([POINTS_TOTAL, 4], dtype='float32')
for j, e in enumerate(initial_positions):
ar_position[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec4()), ar_position, GL_DYNAMIC_COPY)
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(0)
# VELOCITY_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[VELOCITY_A + i])
ar_velocities = np.empty([POINTS_TOTAL, 3], dtype='float32')
for j, e in enumerate(initial_velocities):
ar_velocities[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec3()), ar_velocities, GL_DYNAMIC_COPY)
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(1)
# CONNECTION
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[CONNECTION])
ar_connection = np.empty([POINTS_TOTAL, 4], dtype='uint32')
for j, e in enumerate(connection_vectors):
ar_connection[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.ivec4()), ar_connection, GL_STATIC_DRAW)
glVertexAttribIPointer(2, 4, GL_INT, 0, None)
glEnableVertexAttribArray(2)
glGenTextures(2, m_pos_tbo)
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[0])
glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, m_vbo[POSITION_A])
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[1])
glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, m_vbo[POSITION_B])
lines = (POINTS_X - 1) * POINTS_Y + (POINTS_Y - 1) * POINTS_X
glGenBuffers(1, m_index_buffer)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_index_buffer)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lines * 2 * ctypes.sizeof(ctypes.c_int), None, GL_STATIC_DRAW)
e = glMapBufferRange(GL_ELEMENT_ARRAY_BUFFER, 0, lines * 2 * ctypes.sizeof(ctypes.c_int), GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
int_array = (ctypes.c_int * (4 * lines * 2)).from_address(e)
n = 0
for j in range(0, POINTS_Y):
for i in range(0, POINTS_X - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = 1 + i + j * POINTS_X
n+=1
for i in range(0, POINTS_X):
for j in range(0, POINTS_Y - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = POINTS_X + i + j * POINTS_X
n+=1
glUnmapBuffer(GL_ELEMENT_ARRAY_BUFFER)
def display(self):
global m_iteration_index
glUseProgram(m_update_program)
glEnable(GL_RASTERIZER_DISCARD)
for i in range( iterations_per_frame, 0, -1):
glBindVertexArray(m_vao[m_iteration_index & 1])
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[m_iteration_index & 1])
m_iteration_index +=1
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, m_vbo[POSITION_A + (m_iteration_index & 1)])
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 1, m_vbo[VELOCITY_A + (m_iteration_index & 1)])
glBeginTransformFeedback(GL_POINTS)
glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
glEndTransformFeedback()
glDisable(GL_RASTERIZER_DISCARD)
black = [ 0.0, 0.0, 0.0, 0.0 ]
glViewport(0, 0, self.width, self.height)
glClearBufferfv(GL_COLOR, 0, black)
glUseProgram(m_render_program)
if (draw_points):
glPointSize(4.0)
glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
if (draw_lines):
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_index_buffer)
glDrawElements(GL_LINES, CONNECTIONS_TOTAL * 2, GL_UNSIGNED_INT, None)
glutSwapBuffers()
def reshape(self, width, height):
self.width = width
self.height = height
def keyboard(self, key, x, y ):
global fullscreen
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
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 - Spring-Mass Simulator')
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()
我从 Superbible OpenGL 7ed 的第 7 章将此程序移植到 python。
移植自：springmass.cpp
sys.getsizeof() 不是 return 对象表示的缓冲区大小，它 return 是对象的大小。
如果您想获得由 ctypes 对象管理的缓冲区的大小，那么您需要我们 ctypes.sizeof。例如：
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lines * 2 * sys.getsizeof(int), None, GL_STATIC_DRAW)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lines * 2 * ctypes.sizeof(ctypes.c_int), None, GL_STATIC_DRAW)
PyGLM 也提供了 glm.sizeof() 功能。例如：
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * sys.getsizeof(glm.vec4()), ar, GL_DYNAMIC_COPY)
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec4), ar, GL_DYNAMIC_COPY)
NumPy provides the .itmesize属性。例如：
np.dtype('float32').itemsize
一个list对象，一行代码即可生成：
initial_positions = [glm.vec4() for _ in range(POINTS_TOTAL)]
initial_velocities = [glm.vec3() for _ in range(POINTS_TOTAL)]
connection_vectors = [glm.ivec3() for _ in range(POINTS_TOTAL)]
要从列表中生成数组，您可以通过 numpy.empty 创建一个空数组。
创建一个二维数组，形状分别为 ([POINTS_TOTAL, 4]) ([POINTS_TOTAL, 3])。 glm 矢量对象可以在循环中赋值。
请注意，积分属性的数组类型必须是 'uint32' 而不是 float32:
# POSITION_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[POSITION_A + i])
ar = np.empty([POINTS_TOTAL, 4], dtype='float32')
for j, e in enumerate(initial_positions):
ar[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec4), ar, GL_DYNAMIC_COPY)
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(0)
# VELOCITY_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[VELOCITY_A + i])
ar = np.empty([POINTS_TOTAL, 3], dtype='float32')
for j, e in enumerate(initial_velocities):
ar[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec3), ar, GL_DYNAMIC_COPY)
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(1)
# CONNECTION
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[CONNECTION])
ar = np.empty([POINTS_TOTAL, 4], dtype='uint32')
for j, e in enumerate(connection_vectors):
ar[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.ivec4), ar, GL_STATIC_DRAW)
glVertexAttribIPointer(2, 4, GL_INT, 0, None)
glEnableVertexAttribArray(2)
说明
int_array = ((ctypes.c_int * 4) * lines * 2).from_address(e)
将生成一个 3 维数组。可以使用一次 *- 运算符生成二维数组，其中所有元素的大小（例如 (ctypes.c_int * (4 * lines * 2))）：
int_array = (ctypes.c_int * (4 * lines * 2)).from_address(e)
n = 0
for j in range(0, POINTS_Y):
for i in range(0, POINTS_X - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = 1 + i + j * POINTS_X
n+=1
for i in range(0, POINTS_X):
for j in range(0, POINTS_Y - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = POINTS_X + i + j * POINTS_X
n+=1
此外，当您生成顶点数组对象和缓冲区对象时还有一个问题。
为对象创建列表：
m_vao = [GLuint(0) for _ in range(2)]
m_vbo = [GLuint(0) for _ in range(5)]
在 for 循环中创建 1 个对象：
for i in range(0, 5):
glGenBuffers(1, m_vbo[i])
for i in range(0, 2):
glGenVertexArrays(1, m_vao[i])
终于可以glBeginTransformFeedback使用了：
for i in range( iterations_per_frame, 0, -1):
glBindVertexArray(m_vao[m_iteration_index & 1])
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[m_iteration_index & 1])
m_iteration_index +=1
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, m_vbo[POSITION_A + (m_iteration_index & 1)])
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 1, m_vbo[VELOCITY_A + (m_iteration_index & 1)])
glBeginTransformFeedback(GL_POINTS)
glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
glEndTransformFeedback()
我更改了iterations_per_frame = 1并跳过了glutIdleFunc，但激活了glutIdleFunc
class Scene:
# [...]
def timer(self, blah):
glutPostRedisplay()
glutTimerFunc( 50, self.timer, 0)
if __name__ == '__main__':
# [...]
#glutIdleFunc(scene.display)
glutTimerFunc( 1000, scene.timer, 0)
得到如下结果：
所以我在使用 opengl 函数时遇到了问题 glBeginTransformFeedback 当我取消对这些行的注释时，发生了错误。它说 1282 invalid operation 虽然很含糊。
我的问题是应该如何处理源代码以取消注释这三行：
#glBeginTransformFeedback(GL_POINTS)
#glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
#glEndTransformFeedback()
一个更广泛的问题是关于如何让它正确呈现的任何建议？
更新：在 Rabbid76 优秀代码的帮助下，程序现在可以运行了！！！非常感谢！
成功!!!!当前输出与预期输出相同：
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
import glm
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()
POSITION_A = 0
POSITION_B = 1
VELOCITY_A = 2
VELOCITY_B = 3
CONNECTION = 4
POINTS_X = 50
POINTS_Y = 50
POINTS_TOTAL = POINTS_X * POINTS_Y
CONNECTIONS_TOTAL = (POINTS_X - 1) * POINTS_Y + (POINTS_Y - 1) * POINTS_X
m_vao = [GLuint(0) for _ in range(2)]
m_vbo = [GLuint(0) for _ in range(5)]
m_index_buffer = GLuint(0)
m_pos_tbo = [GLuint(0), GLuint(0)]
m_update_program = GLuint(0)
m_render_program = GLuint(0)
m_C_loc = GLuint(0)
m_iteration_index = 0
draw_points = True
draw_lines = True
iterations_per_frame = 16
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 load_shaders():
global m_update_program
global m_render_program
vs = GLuint(0)
fs = GLuint(0)
buffer = ''
vs = shader_load("update.vs.glsl", GL_VERTEX_SHADER)
if (m_update_program):
glDeleteProgram(m_update_program)
m_update_program = glCreateProgram()
glAttachShader(m_update_program, vs)
# static const char * tf_varyings[] =
# {
# "tf_position_mass",
# "tf_velocity"
# }
# tricky to convert string array to string pointer
tf_varyings = ["tf_position_mass", "tf_velocity"]
# Prepare ctypes data containing the list tf_varyings of strings
array_type = ctypes.c_char_p * len(tf_varyings)
buff = array_type()
for i, e in enumerate(tf_varyings):
buff[i] = e.encode()
# ctypes.c_char
tf_varyings_chrpp = ctypes.cast(ctypes.pointer(buff), ctypes.POINTER(ctypes.POINTER(GLchar)))
glTransformFeedbackVaryings(m_update_program, 2, tf_varyings_chrpp, GL_SEPARATE_ATTRIBS)
glLinkProgram(m_update_program)
glGetShaderInfoLog(vs)
glGetProgramInfoLog(m_update_program)
glDeleteShader(vs)
vs = shader_load("render.vs.glsl", GL_VERTEX_SHADER)
fs = shader_load("render.fs.glsl", GL_FRAGMENT_SHADER)
if (m_render_program):
glDeleteProgram(m_render_program)
m_render_program = glCreateProgram()
glAttachShader(m_render_program, vs)
glAttachShader(m_render_program, fs)
glLinkProgram(m_render_program)
class Scene:
def __init__(self, width, height):
global m_vao
global m_vbo
i = 0
j = 0
load_shaders()
initial_positions = [glm.vec4() for _ in range(POINTS_TOTAL)]
initial_velocities = [glm.vec3() for _ in range(POINTS_TOTAL)]
connection_vectors = [glm.ivec3() for _ in range(POINTS_TOTAL)]
n=0
for j in range(0, POINTS_Y):
fj = float(j) / float(POINTS_Y)
for i in range(0, POINTS_X):
fi = float(i) / float(POINTS_X)
initial_positions[n] = glm.vec4((fi - 0.5) * float(POINTS_X), (fj - 0.5) * float(POINTS_Y), 0.6 * sin(fi) * cos(fj), 1.0)
initial_velocities[n] = glm.vec3(0.0)
connection_vectors[n] = glm.ivec4(-1)
if (j != (POINTS_Y - 1)):
if (i != 0):
connection_vectors[n][0] = n - 1
if (j != 0):
connection_vectors[n][1] = n - POINTS_X
if (i != (POINTS_X - 1)):
connection_vectors[n][2] = n + 1
if (j != (POINTS_Y - 1)):
connection_vectors[n][3] = n + POINTS_X
n+=1
for i in range(0, 2):
glGenVertexArrays(1, m_vao[i])
for i in range(0, 5):
glGenBuffers(i+1, m_vbo[i])
for i in range(0, 2):
glBindVertexArray(m_vao[i])
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[POSITION_A + i])
# POSITION_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[POSITION_A + i])
ar_position = np.empty([POINTS_TOTAL, 4], dtype='float32')
for j, e in enumerate(initial_positions):
ar_position[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec4()), ar_position, GL_DYNAMIC_COPY)
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(0)
# VELOCITY_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[VELOCITY_A + i])
ar_velocities = np.empty([POINTS_TOTAL, 3], dtype='float32')
for j, e in enumerate(initial_velocities):
ar_velocities[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec3()), ar_velocities, GL_DYNAMIC_COPY)
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(1)
# CONNECTION
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[CONNECTION])
ar_connection = np.empty([POINTS_TOTAL, 4], dtype='uint32')
for j, e in enumerate(connection_vectors):
ar_connection[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.ivec4()), ar_connection, GL_STATIC_DRAW)
glVertexAttribIPointer(2, 4, GL_INT, 0, None)
glEnableVertexAttribArray(2)
glGenTextures(2, m_pos_tbo)
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[0])
glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, m_vbo[POSITION_A])
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[1])
glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, m_vbo[POSITION_B])
lines = (POINTS_X - 1) * POINTS_Y + (POINTS_Y - 1) * POINTS_X
glGenBuffers(1, m_index_buffer)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_index_buffer)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lines * 2 * ctypes.sizeof(ctypes.c_int), None, GL_STATIC_DRAW)
e = glMapBufferRange(GL_ELEMENT_ARRAY_BUFFER, 0, lines * 2 * ctypes.sizeof(ctypes.c_int), GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
int_array = (ctypes.c_int * (4 * lines * 2)).from_address(e)
n = 0
for j in range(0, POINTS_Y):
for i in range(0, POINTS_X - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = 1 + i + j * POINTS_X
n+=1
for i in range(0, POINTS_X):
for j in range(0, POINTS_Y - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = POINTS_X + i + j * POINTS_X
n+=1
glUnmapBuffer(GL_ELEMENT_ARRAY_BUFFER)
def display(self):
global m_iteration_index
glUseProgram(m_update_program)
glEnable(GL_RASTERIZER_DISCARD)
for i in range( iterations_per_frame, 0, -1):
glBindVertexArray(m_vao[m_iteration_index & 1])
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[m_iteration_index & 1])
m_iteration_index +=1
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, m_vbo[POSITION_A + (m_iteration_index & 1)])
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 1, m_vbo[VELOCITY_A + (m_iteration_index & 1)])
glBeginTransformFeedback(GL_POINTS)
glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
glEndTransformFeedback()
glDisable(GL_RASTERIZER_DISCARD)
black = [ 0.0, 0.0, 0.0, 0.0 ]
glViewport(0, 0, self.width, self.height)
glClearBufferfv(GL_COLOR, 0, black)
glUseProgram(m_render_program)
if (draw_points):
glPointSize(4.0)
glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
if (draw_lines):
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_index_buffer)
glDrawElements(GL_LINES, CONNECTIONS_TOTAL * 2, GL_UNSIGNED_INT, None)
glutSwapBuffers()
def reshape(self, width, height):
self.width = width
self.height = height
def keyboard(self, key, x, y ):
global fullscreen
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
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 - Spring-Mass Simulator')
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()
我从 Superbible OpenGL 7ed 的第 7 章将此程序移植到 python。
移植自：springmass.cpp
sys.getsizeof() 不是 return 对象表示的缓冲区大小，它 return 是对象的大小。
如果您想获得由 ctypes 对象管理的缓冲区的大小，那么您需要我们 ctypes.sizeof。例如：
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lines * 2 * sys.getsizeof(int), None, GL_STATIC_DRAW)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lines * 2 * ctypes.sizeof(ctypes.c_int), None, GL_STATIC_DRAW)
PyGLM 也提供了 glm.sizeof() 功能。例如：
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * sys.getsizeof(glm.vec4()), ar, GL_DYNAMIC_COPY)
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec4), ar, GL_DYNAMIC_COPY)
NumPy provides the .itmesize属性。例如：
np.dtype('float32').itemsize
一个list对象，一行代码即可生成：
initial_positions = [glm.vec4() for _ in range(POINTS_TOTAL)]
initial_velocities = [glm.vec3() for _ in range(POINTS_TOTAL)]
connection_vectors = [glm.ivec3() for _ in range(POINTS_TOTAL)]
要从列表中生成数组，您可以通过 numpy.empty 创建一个空数组。
创建一个二维数组，形状分别为 ([POINTS_TOTAL, 4]) ([POINTS_TOTAL, 3])。 glm 矢量对象可以在循环中赋值。
请注意，积分属性的数组类型必须是 'uint32' 而不是 float32:
# POSITION_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[POSITION_A + i])
ar = np.empty([POINTS_TOTAL, 4], dtype='float32')
for j, e in enumerate(initial_positions):
ar[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec4), ar, GL_DYNAMIC_COPY)
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(0)
# VELOCITY_A
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[VELOCITY_A + i])
ar = np.empty([POINTS_TOTAL, 3], dtype='float32')
for j, e in enumerate(initial_velocities):
ar[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.vec3), ar, GL_DYNAMIC_COPY)
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, None)
glEnableVertexAttribArray(1)
# CONNECTION
glBindBuffer(GL_ARRAY_BUFFER, m_vbo[CONNECTION])
ar = np.empty([POINTS_TOTAL, 4], dtype='uint32')
for j, e in enumerate(connection_vectors):
ar[j] = e
glBufferData(GL_ARRAY_BUFFER, POINTS_TOTAL * glm.sizeof(glm.ivec4), ar, GL_STATIC_DRAW)
glVertexAttribIPointer(2, 4, GL_INT, 0, None)
glEnableVertexAttribArray(2)
说明
int_array = ((ctypes.c_int * 4) * lines * 2).from_address(e)
将生成一个 3 维数组。可以使用一次 *- 运算符生成二维数组，其中所有元素的大小（例如 (ctypes.c_int * (4 * lines * 2))）：
int_array = (ctypes.c_int * (4 * lines * 2)).from_address(e)
n = 0
for j in range(0, POINTS_Y):
for i in range(0, POINTS_X - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = 1 + i + j * POINTS_X
n+=1
for i in range(0, POINTS_X):
for j in range(0, POINTS_Y - 1):
int_array[n] = i + j * POINTS_X
n+=1
int_array[n] = POINTS_X + i + j * POINTS_X
n+=1
此外，当您生成顶点数组对象和缓冲区对象时还有一个问题。
为对象创建列表：
m_vao = [GLuint(0) for _ in range(2)]
m_vbo = [GLuint(0) for _ in range(5)]
在 for 循环中创建 1 个对象：
for i in range(0, 5):
glGenBuffers(1, m_vbo[i])
for i in range(0, 2):
glGenVertexArrays(1, m_vao[i])
终于可以glBeginTransformFeedback使用了：
for i in range( iterations_per_frame, 0, -1):
glBindVertexArray(m_vao[m_iteration_index & 1])
glBindTexture(GL_TEXTURE_BUFFER, m_pos_tbo[m_iteration_index & 1])
m_iteration_index +=1
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, m_vbo[POSITION_A + (m_iteration_index & 1)])
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 1, m_vbo[VELOCITY_A + (m_iteration_index & 1)])
glBeginTransformFeedback(GL_POINTS)
glDrawArrays(GL_POINTS, 0, POINTS_TOTAL)
glEndTransformFeedback()
我更改了iterations_per_frame = 1并跳过了glutIdleFunc，但激活了glutIdleFunc
class Scene:
# [...]
def timer(self, blah):
glutPostRedisplay()
glutTimerFunc( 50, self.timer, 0)
if __name__ == '__main__':
# [...]
#glutIdleFunc(scene.display)
glutTimerFunc( 1000, scene.timer, 0)
得到如下结果：