我有一项任务是在OpenGL中在屏幕外渲染事物。我必须在帧缓冲区中渲染事物，但无需在OpenGL窗口中显示它。
import sys
from PIL import Image
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
import numpy as np
# define shader code
vertex_code='''
uniform float scale;
attribute vec2 position;
attribute vec4 color;
varying vec4 v_color;
attribute vec2 TexCoordIn;
varying vec2 TexCoordOut;
void main()
{
gl_Position = vec4(position*scale, 0.0, 1.0);
v_color = color;
TexCoordOut = TexCoordIn;
}'''
fragment_code='''
varying vec4 v_color;
varying vec2 TexCoordOut;
uniform sampler2D Texture;
uniform vec2 originPosition;
uniform vec2 targetPosition;
vec2 curveWarp(vec2 textureCoord, vec2 originPosition, vec2 targetPosition, float radius)
{
vec2 offset = vec2(0.0);
vec2 result = vec2(0.0);
vec2 direction = targetPosition - originPosition;
float infect = distance(textureCoord, originPosition)/radius;
infect = 1.0 - infect;
infect = clamp(infect, 0.0, 1.0);
offset = direction * infect;
result = textureCoord - offset;
return result;
}
void main()
{
vec2 coordinate = vec2(0.0);
float radius = 0.5;
coordinate = curveWarp(TexCoordOut,originPosition,targetPosition,radius);
gl_FragColor = v_color*0.000000000001 + texture2D(Texture, coordinate);
}'''
#define vertex and color array
data = np.zeros(4, dtype = [ ("position", np.float32, 2), ("color", np.float32, 4),("textureCoord",np.float32,2)] )
data['color'] = [ (1,1,0,1), (1,1,0,1), (1,1,0,1), (1,1,0,1) ]
data['position'] = [ (-1,-1), (-1,+1), (+1,-1), (+1,+1) ]
data['textureCoord']= [ (0,0), (0,1), (1,0), (1,1) ]
#define debug function
def showTextureInGLTexture2D():
im = glGetTexImage( GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE )
image=Image.frombuffer("RGBA",(512,512),im, 'raw', 'RGBA', 0, 1)
image.show()
#define useful function
def display():
glClear(GL_COLOR_BUFFER_BIT)
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4)
glutSwapBuffers()
def reshape(width,height):
glViewport(0, 0, width, height)
#step1 init the context
def init(img_path):
image = Image.open(img_path)
glutInit()
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB)
glutCreateWindow('Hello world!')
glutReshapeWindow(image.width,image.height)
glutReshapeFunc(reshape)
glutDisplayFunc(display)
glutKeyboardFunc(keyboard)
return image
#step 2
def initShaderProgram():
program = glCreateProgram()
vertex = glCreateShader(GL_VERTEX_SHADER)
fragment = glCreateShader(GL_FRAGMENT_SHADER)
# Set shaders source
glShaderSource(vertex, vertex_code)
glShaderSource(fragment, fragment_code)
# Compile shaders
glCompileShader(vertex)
glCompileShader(fragment)
fragSuccess=glGetShaderiv(fragment, GL_COMPILE_STATUS)
vertSuccess=glGetShaderiv(vertex, GL_COMPILE_STATUS)
print("vertext shader compile success [%s]" %(vertSuccess,))
print( "fragment shader compile success [%s]" %(fragSuccess,))
if vertSuccess==0:
print (glGetShaderInfoLog(vertex))
sys.exit(0)
if fragSuccess==0:
print (glGetShaderInfoLog(fragment))
sys.exit(0)
glAttachShader(program, vertex)
glAttachShader(program, fragment)
glLinkProgram(program)
linksucc=glGetProgramiv(program,GL_LINK_STATUS);
print( "link program success [%s]" %(linksucc,))
glUseProgram(program)
return program
#step 3.1 optional setup texture
def getTextureFromFile(image_file):
#convert file to bytes
image = image_file.transpose(Image.FLIP_TOP_BOTTOM)
image = image.convert("RGBA")
byteImage =np.array(list(image.getdata()), np.uint8)
#setup texture
texIndex=glGenTextures(1)
glEnable( GL_TEXTURE_2D )
glBindTexture(GL_TEXTURE_2D,texIndex)
glPixelStorei(GL_UNPACK_ALIGNMENT,1)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
#make the texture the default
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texIndex, 0)
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,image.width,image.height,0,GL_RGBA,GL_UNSIGNED_BYTE,byteImage)
return texIndex
#step 4.1 optional get the image from BufferFrame
def saveImageFromFBO(image):
glReadBuffer(GL_COLOR_ATTACHMENT0)
glPixelStorei(GL_PACK_ALIGNMENT, 1)
data = glReadPixels (0, 0, image.width, image.height, GL_RGB, GL_UNSIGNED_BYTE)
image = Image.new ("RGB", (image.width, image.height), (0, 0, 0))
image.frombytes (data)
image = image.transpose(Image.FLIP_TOP_BOTTOM)
image.save ('9_result.jpg')
#step 4 optional if need to OSR generate a BufferFrame
def setupSelfDefineFBO(program,image):
# Setup framebuffer
framebuffer = glGenFramebuffers (1)
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer)
# Setup depthbuffer
depthbuffer = glGenRenderbuffers (1)
glBindRenderbuffer (GL_RENDERBUFFER,depthbuffer)
glRenderbufferStorage (GL_RENDERBUFFER, GL_DEPTH_COMPONENT, image.width, image.height)
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthbuffer)
#first init VBO, then other parameters
buffer = glGenBuffers(1) # Request a buffer slot from GPU
glBindBuffer(GL_ARRAY_BUFFER, buffer) # Make this buffer the default one
glBufferData(GL_ARRAY_BUFFER, data.nbytes, data, GL_DYNAMIC_DRAW) # Upload data
# Create texture to render to
# glBufferData(GL_FRAMEBUFFER, data.nbytes, data, GL_DYNAMIC_DRAW)
loc = glGetAttribLocation(program, "position") #get the index of the attribute in program
glEnableVertexAttribArray(loc) #allow this attribute decide by index can be use
stride = data.strides[0] #define how to read buffer
offset = ctypes.c_void_p(0) #define the offset where the data begin in buffer
glVertexAttribPointer(loc, 2, GL_FLOAT, False, stride, offset)
offset = ctypes.c_void_p(data.dtype["position"].itemsize)
loc = glGetAttribLocation(program, "color")
glEnableVertexAttribArray(loc)
glVertexAttribPointer(loc, 4, GL_FLOAT, False, stride, offset)
#setup other parameters
loc = glGetUniformLocation(program, "scale")
glUniform1f(loc, 1.0)
originPosition = glGetUniformLocation(program, "originPosition")
glUniform2f(originPosition, 0.5, 0.5 )
targetPosition = glGetUniformLocation(program, "targetPosition")
glUniform2f(targetPosition, 0.47, 0.47 )
# following code to bind uniform texture if needed
aTexture=getTextureFromFile(image)
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D,aTexture)
loc=glGetUniformLocation(program,"Texture")
textureId=glGetIntegerv(GL_TEXTURE_BINDING_2D) #find out the id of the current texture bind to GL_TEXTURE_2D
glUniform1i(loc,textureId)
loc= glGetAttribLocation(program, "TexCoordIn")
glEnableVertexAttribArray(loc)
offset=ctypes.c_void_p(data.dtype["color"].itemsize+8)
glVertexAttribPointer(loc,2,GL_FLOAT,False,stride,offset)
status = glCheckFramebufferStatus (GL_FRAMEBUFFER)
if status != GL_FRAMEBUFFER_COMPLETE:
print( "Error in framebuffer activation")
saveImageFromFBO(image)
glBindFramebuffer(GL_FRAMEBUFFER, GL_NONE)
glDeleteTextures ([aTexture])
glDeleteFramebuffers (1,[framebuffer])
print( 'save image from FBO success')
def keyboard( keycode, x, y ):
# print(keycode)
# if (keycode == 'b'+'q'):
# sys.exit()
# elif (keycode == 'b'+' '):
saveImageFromFBO(image)
if (__name__ == '__main__'):
image = init('9.jpg')
program = initShaderProgram()
setupSelfDefineFBO(program,image)
该代码无法正确渲染图片，着色器不起作用，但是可以保存原始图像。我在互联网上找不到有用的信息。有什么想法为什么这行不通吗？以及我该如何解决？
首先，帧缓冲区需要一个颜色缓冲区：
def setupSelfDefineFBO(program,image):
fbWidth, fbHeight = image.width, image.height
# Setup framebuffer
framebuffer = glGenFramebuffers (1)
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer)
# Setup colorbuffer
colorbuffer = glGenRenderbuffers (1)
glBindRenderbuffer(GL_RENDERBUFFER, colorbuffer)
glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA, fbWidth, fbHeight)
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorbuffer)
# Setup depthbuffer
depthbuffer = glGenRenderbuffers (1)
glBindRenderbuffer(GL_RENDERBUFFER,depthbuffer)
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, fbWidth, fbHeight)
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthbuffer)
# check status
status = glCheckFramebufferStatus (GL_FRAMEBUFFER)
if status != GL_FRAMEBUFFER_COMPLETE:
print( "Error in framebuffer activation")
# [...]
查看端口的大小必须适应于帧缓冲区（glViewport）的大小：
glViewport纹理对象与纹理采样器制服的绑定起点是纹理单位。您必须将纹理单位分配给纹理采样器统一而不是纹理对象（名称）ID（def setupSelfDefineFBO(program,image):
# [...]
glViewport(0, 0, fbWidth, fbHeight)
# [...]
为0，GL_TEXTURE0 ...为1）：
GL_TEXTURE1要运行着色器程序，必须绘制一些几何图形。该应用程序设置了顶点坐标和属性，但从未绘制几何ID。通过def setupSelfDefineFBO(program,image):
# [...]
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D,aTexture)
loc=glGetUniformLocation(program,"Texture")
glUniform1i(loc, 0) # <----
# [...]
GL_TRIANGLE_STRIP绘制屏幕空间四边形：
Triangle primitives
def setupSelfDefineFBO(program,image):
# [...]
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4)
saveImageFromFBO(fbWidth, fbHeight)
glBindFramebuffer(GL_FRAMEBUFFER, GL_NONE)
glViewport(0, 0, 512, 512)
# [...]