I've seen many docs about the concurrency programming for opengles(iOS), still can't solve my problem, so I ask here for your help.
I followed the instruction, create two threads, each thread owns a context, and make them the same sharegroup, render objects in main thread, and create object in second thread.
What I can't understand is I just can't render the objects that created in the second threads. (if I move the object creation code back to main thread then it works.)
I did glFlush() after the object's setup sequence. I just don't get it.
I use the default opengl demo App that generated by the XCode4. and add codes like this for testing:
-(void)setupGL
{
[EAGLContext setCurrentContext:self.context];
self.context2 = [ [ EAGLContext alloc ] initWithAPI: kEAGLRenderingAPIOpenGLES2 sharegroup: self.context.sharegroup ];
if( !self.context2 )
{
printf( " error !!!" );
}
if( self.context.sharegroup != self.context2.sharegroup )
{
printf( " error2 !!!" );
}
... self.effect = ....
... glEnable....
...
[ self performSelectorInBackground: @selector(indicator) withObject: nil ];
}
-(void)indicator // run this in another thread
{
[EAGLContext setCurrentContext:self.context2];
glGenVertexArraysOES(1, &_vertexArray);
glBindVertexArrayOES(_vertexArray);
glGenBuffers(1, &_vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer2);
glBufferData(GL_ARRAY_BUFFER, sizeof(gCubeVertexData2), gCubeVertexData2, GL_STATIC_DRAW);
glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(0));
glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(12));
glBindVertexArrayOES(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glFlush();
[ EAGLContext setCurrentContext: nil ];
}
- (void)update
{
.... generated by XCode4 ....
}
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
.... generated by XCode4 ....
}
What did I miss ??
I found that if I generate and setup objects in main thread, I can still bind and modify objects' data in second thread, and render in main thread correctly.
