glDeleteBuffers crashes during destructor call

Question

Hi I am using VBO to load image texture and then draw it in C++. VBO id generate and bind and draw occurs here

void ViewManager::render(){

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_TEXTURE_2D);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
if(decompressTileImage->tileTexure == 0)
    {
        loadTexture(decompressTileImage);
        glGenBuffers(1,&decompressTileImage->VBOId);
        glBindBuffer(GL_ARRAY_BUFFER,decompressTileImage->VBOId);
        glBufferData(GL_ARRAY_BUFFER,sizeof(*(this->tileCoordList))+sizeof(*(this->tileTextureCoordList)),0,GL_STATIC_DRAW);
        glBufferSubData(GL_ARRAY_BUFFER,0,sizeof(*(this->tileCoordList)),this->tileCoordList);
        glBufferSubData(GL_ARRAY_BUFFER,sizeof(*(this->tileCoordList)),sizeof(*(this->tileTextureCoordList)),this->tileTextureCoordList);

    }
    else
    {
        glBindBuffer(GL_ARRAY_BUFFER,decompressTileImage->VBOId);
        glBindTexture(GL_TEXTURE_2D, decompressTileImage->tileTexure);
    }

    glColor4f(1.0f, 1.0f, 1.0f, textureAlpha);

    if(textureAlpha < 1.0)
    {
        textureAlpha = textureAlpha + .03;
        this->tiledMapView->renderNow();
    }

glTexCoordPointer(3, GL_FLOAT, 0, (void*)sizeof(*(this->tileCoordList)));
glVertexPointer(3, GL_FLOAT, 0, 0);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glBindBuffer(GL_ARRAY_BUFFER,0);
glDisable(GL_BLEND);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisable(GL_TEXTURE_2D);
}

This function is in a class named MapTile. MapTile is created 35 times for 35 images downloaded from the internet. And then a thread calls this method 35 times for 35 MapTile object and keeps doing it. That is why I first check if the method is called for the first time so that I can load data and generate VBO id only once for each MapTile object. I check this with if(decompressTileImage->tileTexure == 0) this line. and then each time I just bind the vbo id to draw. No need to load the data again.

Here decompressTileImage is a TextureImageInfo class. The implementation is

#include "TextureImageInfo.h"
TextureImageInfo::TextureImageInfo(unsigned char * image,GLuint format,int texWidth,int texHeight,int imageWidth,int imageHeight,float tex_x,float tex_y)
{
// TODO Auto-generated constructor stub
this->format = format;
this->image = image;
this->imageHeight = imageHeight;
this->imageWidth = imageWidth;
this->texHeight = texHeight;
this->texWidth = texWidth;
this->tileTexure = 0;
this->VBOId = 0;
this->time = 0;

}

TextureImageInfo::~TextureImageInfo()
{
if(VBOId!=0)
    glDeleteBuffers(1,&VBOId);
}

It draws and does everything fine but crashes when I try to clean up the memory in the destructor of TextureImageInfo class which is given here. I don't understand why. I checked to see if the VBOId is generated and loaded in the memory with the if condition in the destructor too.

What type of crash do you get? And where the destructor is called (is it in the same thread as OpenGL context)? — Kimi, Mar 21 '13 at 11:16
I think you are right. I have done all the vbo related work in QThread. But I am deleting the buffer from main thread. Can you please make this an answer? — Tahlil, Mar 21 '13 at 11:21
I am creating EGL context in QThread. So all the opengl related works should be done in QThread also. But here the destructor is called from main thread. — Tahlil, Mar 21 '13 at 11:28

Kimi · Accepted Answer · 2013-03-21T11:39:19.253

As indicated in the comments, OpendGL ES commands should be submitted from the same thread where the context was created.

From the Blackberry docs Parallel processing with OpenGL ES:

It is important to note that each OpenGL ES rendering context targets a single thread of execution.

If you want to render multiple scenes, you can separate each scene into its own thread, making sure each thread has its own context

glDeleteBuffers crashes during destructor call

1 Answers1