Rendering Chmura punktów Kinect z obiektem bufora wierzchołków (VBO)

Question

Próbuję utworzyć wizualizator chmury punktów dynamicznych. Punkty są aktualizowane w każdej klatce za pomocą czujnika Kinect. Aby pobrać ramki, używam OpenCV i GLUT do wyświetlenia. Interfejs API OpenCV zwraca wartość 640 x 480 (liczba zmiennopozycyjna *) dla pozycji punktów xyz oraz wartość 640 x 480 (int *) dla danych koloru rgb. Aby uzyskać maksymalną wydajność, próbuję użyć Vertex Buffer Object w trybie strumieniowym zamiast prostego Vertex Array. Jestem w stanie renderować to z Vertex Array, ale nic nie jest renderowane przy mojej implementacji VBO. Próbowałem różnych deklaracji w deklaracjach, ale nie mogę znaleźć tego, czego mi brakuje. Czy ktoś może wskazać mi właściwy kierunek? Oto kod simpflified: (Ive rewrited złą wersję jako poproszony przez Christian Rau, więc wy może zrozumieć swoje błędy)

int main() 
{ 
    //Delaring variables, inittiating glut, setting camera and checking the compatibility as http://www.songho.ca/opengl/gl_vbo.html 
    glutDisplayFunc(displayCB); 
    glutIdleFunc(displayCB); 
    ... 
    //Inittiating the vertex buffers 
    if(vboSupported) 
    { 
     glGenBuffers(1, &vertex_buffer); 
     glBindBuffer(GL_ARRAY_BUFFER_ARB, buffer); 
     glBufferData(GL_ARRAY_BUFFER_ARB, (sizeof(GLfloat) * 640 * 480 * 3), 0, GL_STREAM_DRAW_ARB); 
     glBufferSubData(GL_ARRAY_BUFFER_ARB, 0, (sizeof(float) * 640 * 480 * 3), point_cloud.points_position); 

     glGenBuffers(2, &color_buffer); 
     glBindBuffer(GL_ARRAY_BUFFER_ARB, buffer); 
     glBufferData(GL_ARRAY_BUFFER_ARB, (sizeof(GLbyte) * 640 * 480 * 3), 0, GL_STREAM_DRAW_ARB); 
     glBufferSubData(GL_ARRAY_BUFFER_ARB, 0, (sizeof(char) * 640 * 480 * 3), point_cloud.points_color); 
    } 
    //glutMainLoop(), cleaning memory, ending main 
    .. 
} 

//Updating the screen 
void displayCB() 
{ 
    point_cloud.update(); 

    // clear buffer 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); 

    // save the initial ModelView matrix before modifying ModelView matrix 
    glPushMatrix(); 

     glBindBuffer(GL_ARRAY_BUFFER_ARB, color_buffer); 
     glBufferSubData(GL_ARRAY_BUFFER_ARB, 0, (sizeof(char) * 640 * 480 * 3), point_cloud.points_color); 
     glColorPointer(3, GL_UNSIGNED_BYTE, 0, 0); 

     glBindBuffer(GL_ARRAY_BUFFER_ARB, vertex_buffer); 
     glBufferSubData(GL_ARRAY_BUFFER_ARB, 0, (sizeof(float) * 640 * 480 * 3), point_cloud.points_position); 
     glVertexPointer(3, GL_FLOAT, 0, 0)); 

     // enable vertex arrays 
     glEnableClientState(GL_VERTEX_ARRAY); 
     glEnableClientState(GL_COLOR_ARRAY); 

     glDrawArrays(GL_POINT, 0, 640*480); 

     glDisableClientState(GL_VERTEX_ARRAY); // disable vertex arrays 
     glDisableClientState(GL_COLOR_ARRAY); 

     glBindBuffer(GL_ARRAY_BUFFER_ARB, 0); 

    glPopMatrix(); 

    glutSwapBuffers(); 
} 

Answer 1

PS: Program jest gotowy do pracy, ale nie widzę dowolna poprawa średniej wydajności w porównaniu z wersją Vertex Array. Czy tak jest w porządku? PROBLEM ZOSTAŁ ROZWIĄZANY. Ive zrobić trzy zmiany:

1 - I though that glGenBuffers first parameter was the number that 
would be associated to the buffer, instead, its the number of 
buffers that would be allocated. This doesn't matter anyway, because 
now I'm using a single buffer and adding all the data to it. Didn't 
solved the problem, but was going in the right way. 

2 - There are two ways of being able to use OpenGL VBO functions. 
First, you can bind the ARB version functions by yourself OR you 
can add glew.h and use glewInit() after starting an OpenGL context. 
The second option is a LOT cleaner and I changed my code so I don't 
use the ARB versions anymore. Still didn't solved the problem. 

3 - Christian Rau asked me for glErrors in the code, so, I wrote it 
after each OpenGL operation in displayCB. After glDrawArrays I got 
an 0x00500 error, that means there is an invalid enum, so I noticed 
I was using GL_POINT as parameter to glDrawArrays, instead of 
GL_POINTS, so silly that makes me want to kill myself. 

Kod końcowy:

//EDIT: Added glew.h as a header and I´m not using the ARB version anymore 
#include <glew.h> 

    int main() 
    { 
     //Declaring variables, initiating glut, setting camera and checking the compatibility as http://www.songho.ca/opengl/gl_vbo.html 
     glutDisplayFunc(displayCB); 
     glutIdleFunc(displayCB); 
     ... 

     //EDIT: IS VERY IMPORTANT TO ADD IT AS SOON AS YOU START AN OPENGL CONTEXT. 
     initGlew(); 

     //Inittiating the vertex buffers 
     if(vboSupported) 
     { 
      //EDIT: I was using two buffers, one for color and another for the vertex. I changed the code so I use a single buffer now. 
      //EDIT: Notice that I'm not using the ARB version of the functions anymore. 
      glGenBuffers(1, &buffer); 
      glBindBuffer(GL_ARRAY_BUFFER_ARB, buffer); 
      glBufferData(GL_ARRAY_BUFFER_ARB, (sizeof(GLfloat) * 640 * 480 * 3) + (sizeof(GLbyte) * 640 * 480 * 3), 0, GL_STREAM_DRAW_ARB); 
     } 
     //glutMainLoop(), cleaning memory, ending main 
     .. 
    } 

    //Updating the screen 
    void displayCB() 
    { 
     point_cloud.update(); 

     // clear buffer 
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); 

     // save the initial ModelView matrix before modifying ModelView matrix 
     glPushMatrix(); 

      glBindBuffer(GL_ARRAY_BUFFER_ARB, buffer); 
      glBufferSubData(GL_ARRAY_BUFFER_ARB, 0, (sizeof(char) * 640 * 480 * 3), point_cloud.points_color); 
      glBufferSubData(GL_ARRAY_BUFFER_ARB, (sizeof(char) * 640 * 480 * 3), (sizeof(float) * 640 * 480 * 3), point_cloud.points_position); 

      // enable vertex arrays 
      glEnableClientState(GL_VERTEX_ARRAY); 
      glEnableClientState(GL_COLOR_ARRAY); 

      glColorPointer(3, GL_UNSIGNED_BYTE, 0, 0); 
      //EDIT: Added the right offset at the vertex pointer position 
      glVertexPointer(3, GL_FLOAT, 0, (void*)(sizeof(char) * 640 * 480 * 3)); 

      //EDIT: Was using GL_POINT instead of GL_POINTS 
      glDrawArrays(GL_POINTS, 0, 640*480); 

      glDisableClientState(GL_VERTEX_ARRAY); // disable vertex arrays 
      glDisableClientState(GL_COLOR_ARRAY); 

      glBindBuffer(GL_ARRAY_BUFFER_ARB, 0); 

     glPopMatrix(); 

     glutSwapBuffers(); 
    }