只有 4 行小代码导致我从 OpenGL Superbible 移植的外星雨程序出现问题。在使用函数 glMapBufferRange
后，我似乎在尝试写入内存时遇到问题更新:Rabbid76 的优秀代码解决了这个问题并提供了有值(value)的解释见解。谢谢。
所需文件:ktxloader.py , aliens.ktx
alienrain.py源码
#!/usr/bin/python3
import sys
import time
sys.path.append("./shared")
#from sbmloader import SBMObject # location of sbm file format loader
from ktxloader import KTXObject # location of ktx file format loader
#from sbmath import m3dDegToRad, m3dRadToDeg, m3dTranslateMatrix44, m3dRotationMatrix44, m3dMultiply, m3dOrtho, m3dPerspective, rotation_matrix, translate, m3dScaleMatrix44
fullscreen = True
import numpy.matlib
import numpy as np
import math
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()
identityMatrix = [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1]
render_prog = GLuint(0)
render_vao = GLuint(0)
tex_alien_array = GLuint(0)
rain_buffer = GLuint(0)
droplet_x_offset = []
droplet_rot_speed = []
droplet_fall_speed = []
seed = 0x13371337
import random
import ctypes
random.seed (0x13371337)
def random_float():
# global seed
# res=0.0
# tmp=0
# seed *= 16807;
# tmp = seed ^ (seed >> 4) ^ (seed << 15);
# res = (tmp >> 9) | 0x3F800000;
# return (res - 1.0);
return (random.random() - 1.0)
class Scene:
def __init__(self, width, height):
global render_prog
global render_vao
global tex_alien_array
global rain_buffer
global droplet_x_offset, droplet_rot_speed, droplet_fall_speed
self.width = width
self.height = height
vs = GLuint(0)
fs = GLuint(0)
vs_source = '''
#version 410 core
layout (location = 0) in int alien_index;
out VS_OUT
{
flat int alien;
vec2 tc;
} vs_out;
struct droplet_t
{
float x_offset;
float y_offset;
float orientation;
float unused;
};
layout (std140) uniform droplets
{
droplet_t droplet[256];
};
void main(void)
{
const vec2[4] position = vec2[4](vec2(-0.5, -0.5),
vec2( 0.5, -0.5),
vec2(-0.5, 0.5),
vec2( 0.5, 0.5));
vs_out.tc = position[gl_VertexID].xy + vec2(0.5);
float co = cos(droplet[alien_index].orientation);
float so = sin(droplet[alien_index].orientation);
mat2 rot = mat2(vec2(co, so),
vec2(-so, co));
vec2 pos = 0.25 * rot * position[gl_VertexID];
gl_Position = vec4(pos.x + droplet[alien_index].x_offset,
pos.y + droplet[alien_index].y_offset,
0.5, 1.0);
vs_out.alien = alien_index % 64;
}
'''
fs_source = '''
#version 410 core
layout (location = 0) out vec4 color;
in VS_OUT
{
flat int alien;
vec2 tc;
} fs_in;
uniform sampler2DArray tex_aliens;
void main(void)
{
color = texture(tex_aliens, vec3(fs_in.tc, float(fs_in.alien)));
}
'''
vs = glCreateShader(GL_VERTEX_SHADER)
glShaderSource(vs, vs_source)
glCompileShader(vs)
glGetShaderInfoLog(vs)
fs = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(fs, fs_source)
glCompileShader(fs)
glGetShaderInfoLog(vs)
render_prog = glCreateProgram()
glAttachShader(render_prog, vs)
glAttachShader(render_prog, fs)
glLinkProgram(render_prog)
glDeleteShader(vs)
glDeleteShader(fs)
glGetProgramInfoLog(render_prog)
glGenVertexArrays(1, render_vao)
glBindVertexArray(render_vao)
ktxobj = KTXObject()
tex_alien_array = ktxobj.ktx_load("aliens.ktx")
glBindTexture(GL_TEXTURE_2D_ARRAY, tex_alien_array)
glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR)
glGenBuffers(1, rain_buffer)
glBindBuffer(GL_UNIFORM_BUFFER, rain_buffer)
glBufferData(GL_UNIFORM_BUFFER, 256*4*4, None, GL_DYNAMIC_DRAW)
for i in range(0, 256):
droplet_x_offset.append(random_float() * 2.0 - 1.0)
droplet_rot_speed.append( (random_float() + 0.5) * (-3.0 if (i & 1) else 3.0) )
droplet_fall_speed.append ( random_float() + 0.2 )
glBindVertexArray(render_vao);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
def display(self):
global rain_buffer
green = [ 0.0, 0.1, 0.0, 0.0 ]
currentTime = time.time()
t = currentTime
glViewport(0, 0, self.width, self.height)
glClearBufferfv(GL_COLOR, 0, green)
glUseProgram(render_prog);
glBindBufferBase(GL_UNIFORM_BUFFER, 0, rain_buffer);
droplet = glMapBufferRange(GL_UNIFORM_BUFFER, 0, 256*4*4, GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
float_array = ((ctypes.c_float * 4) * 256).from_address(droplet)
for i in range(0, 256):
float_array[i][0] = droplet_x_offset[i] + 2
float_array[i][1] = 2.0-math.fmod((t + float(i)) * droplet_fall_speed[i], 4.31 ) * random_float()
float_array[i][2] = droplet_rot_speed[i] * t * random_float() * math.pi
float_array[i][3] = 0.0
glUnmapBuffer(GL_UNIFORM_BUFFER);
for alien_index in range(0, 256):
glVertexAttribI1i(0, alien_index);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glutSwapBuffers()
def reshape(self, width, height):
self.width = width
self.height = height
def keyboard(self, key, x, y ):
global fullscreen
global many_cubes
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 - Alien Rain')
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()
当前输出是: 更新:与预期输出非常相似。除了它非常快而且每个外星人的旋转都没有预期的输出那么平滑。如果有人想修改这些值来获得它，请这样做。否则这个问题就得到了回答。
输出应该是:
这是 alienrain.cpp用于创建 alienrain.py
最佳答案
首先，glBufferData的第二个参数是以字节为单位的缓冲区数据。
由于glsl数据结构是
struct droplet_t
{
float x_offset;
float y_offset;
float orientation;
float unused;
};
layout (std140) uniform droplets
{
droplet_t droplet[256];
};
缓冲区大小为 4*4*256，因为 float 的大小为 4，结构体有 4 个 flaot 类型的元素，数组有 256元素
glBufferData(GL_UNIFORM_BUFFER, 256*4*4, None, GL_DYNAMIC_DRAW)
说明
droplet = glMapBufferRange(GL_UNIFORM_BUFFER, 0, 256*4*4, GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
返回一个指向分配的具有适当大小的内存区域的指针。你必须用数据填充这个内存。
最简单的解决方案是使用(在 python 中内置)库 ctypes , 它具有方便的功能 .from_address() :
This method returns a ctypes type instance using the memory specified by address.
所以指令
float_array = ((ctypes.c_float * 4) * 256).from_address(droplet)
将二维数组“包装”到由 droplet 寻址的内存中，有 256 个元素，每个元素有 4 个 float 类型的元素。
可以通过简单的赋值语句将值设置到数组中。例如:
import random
import math
import ctypes
glBindBufferBase(GL_UNIFORM_BUFFER, 0, rain_buffer);
droplet = glMapBufferRange(GL_UNIFORM_BUFFER, 0, 256*4*4, GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)
float_array = ((ctypes.c_float * 4) * 256).from_address(droplet)
for i in range(0, 256):
float_array[i][0] = random.random() * 2 -1
float_array[i][1] = random.random() * 2 -1
float_array[i][2] = random.random() * math.pi * 2
float_array[i][3] = 0.0
关于python - 尝试使用 opengl 函数 glMapBufferRange 在 python 中制作 alienrain，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56768267/