Texture sharing between OpenGL contexts with GLFW3 does not work

Question

The following program is assumed:

• Create invisible GLFWwindow* masterWindow
• Load the texture from the file, while the active OpenGL context is the one associated with masterWindow
• create GLFWwindow* childWindow, while sharing is activated between this OpenGL context window and the contextmasterWindow
• display a fullscreen square with texture in childWindow

However, this does not work, i.e. instead of texture, I get random fragments of graphic memory displayed in childWindow. Texture mapping works if I make the context childWindowcurrent before loading, so I think the problem is not that my problem is not related to my shaders or my texture loading program (which I took here, https://github.com/ DavidEGrayson / ahrs-visualizer / blob / master / png_texture.cpp ). I understand that I need to share the texture (see the answer to this question SO: OpenGL - share existing textures with future contexts? ), So what am I doing wrong? In case that matters, I use a late 2008 Macbook with NVIDIA 9400m and Mavericks / OpenGL 3.3 installed.

#include <iostream>
#define GLEW_STATIC
#include <glew.h>
#include <glfw3.h>

const char* vShader =
  "#version 150 core\n"
  "in vec2 vertex;"
  "in vec2 vertexUV;"
  "out vec2 UV;"
  "void main() {gl_Position = vec4(vertex,0,1);UV=vertexUV;}";
const char* fShader =
 "#version 150 core\n"
 "uniform sampler2D sampler;"
 "in vec2 UV;"
 "out vec4 color;"
 "void main() {color = texture(sampler, UV);}";

GLuint png_texture_load(const char * file_name, unsigned int * width=NULL, unsigned int * height=NULL);
GLuint make_program(const char* vShader, const char* fShader);

GLFWwindow* masterWindow(NULL);

void create_window_with_texture(GLuint texture)
{
  GLFWwindow* childWindow(glfwCreateWindow(256,256, "", NULL, masterWindow));
  glfwMakeContextCurrent(childWindow);

  // texture appears if loaded from here
  // texture=png_texture_load("rose.png");                                                                                                               

  GLfloat vertices[]={-1,-1,1,-1,-1,1,1,1, // window corners in clip space                                                                               
                  0,0,1,0,0,1,1,1};    // corners in uv-space                                                                                        
  GLubyte indices[]={0,2,1,3};             // points for a two triangle strip                                                                            

  GLuint vArray,vBuffer,iBuffer;
  glGenVertexArrays(1,&vArray);glBindVertexArray(vArray);
  glGenBuffers(1,&vBuffer);glBindBuffer(GL_ARRAY_BUFFER,vBuffer);
  glGenBuffers(1,&iBuffer);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,iBuffer);
  glBufferData(GL_ARRAY_BUFFER,sizeof(vertices),vertices,GL_DYNAMIC_DRAW);
  glBufferData(GL_ELEMENT_ARRAY_BUFFER,sizeof(indices),indices,GL_DYNAMIC_DRAW);

  GLuint program(make_program(vShader,fShader));
  glUseProgram(program);
  glUniform1i(glGetUniformLocation(program,"sampler"),0);
  GLuint vertexPtr(GLuint(glGetAttribLocation(program,"vertex")));
  glEnableVertexAttribArray(vertexPtr);
  GLuint vertexUVPtr(GLuint(glGetAttribLocation(program, "vertexUV")));
  glEnableVertexAttribArray(vertexUVPtr);
  glVertexAttribPointer(vertexPtr, 2, GL_FLOAT, GL_FALSE, 0, (const GLvoid*)0 );
  glVertexAttribPointer(vertexUVPtr, 2, GL_FLOAT, GL_FALSE, 0, (const GLvoid*)32);

  glActiveTexture(GL_TEXTURE0);
  glDisable(GL_DEPTH_TEST);
  glDisable(GL_BLEND);

  glBindTexture(GL_TEXTURE_2D,texture);
  glDrawElements(GL_TRIANGLE_STRIP,4, GL_UNSIGNED_BYTE, (GLvoid*)0);

  glfwSwapBuffers(childWindow);
}

int main()
{
  if (!glfwInit())
    return -1;
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR,3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR,2);
  glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT,GL_TRUE);
  glfwWindowHint(GLFW_OPENGL_PROFILE,GLFW_OPENGL_CORE_PROFILE);
  glfwWindowHint(GLFW_VISIBLE,GL_FALSE);
  masterWindow=glfwCreateWindow(10,10, "", NULL,NULL);
  glfwWindowHint(GLFW_VISIBLE,GL_TRUE);
  glfwWindowHint(GLFW_SAMPLES, 4);
  glfwMakeContextCurrent(masterWindow);
  glewExperimental = GL_TRUE;
  GLenum err = glewInit();
  if(GLEW_OK!=err)
    return -1;
  glGetError(); // catch benign glewInit() invalid enum error                                                                                            

  GLuint texture(0);
  texture=png_texture_load("rose.png");

  create_window_with_texture(texture);

  std::cin.get();

  return 0;
}

Answer 1

, OpenGL . GL/GPU. , GL , , . . glFinish() , . , , / GL hande .

, , , ( API) glFinish ( ).