opengl es 2.0 Reder to texture iOS

- (void)setupTexture {

GLint width;
GLint height;

width = self.frame.size.width;
height = self.frame.size.height;

glGenTextures(1, &_textureId);

glBindTexture(GL_TEXTURE_2D,_textureId);

glTexImage2D(GL_TEXTURE_2D,0,
GL_RGBA, width, height,0,
GL_RGBA,GL_UNSIGNED_BYTE,NULL);

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,
GL_NEAREST);

}

- (void)setupMemFrameBuffer {
glGenFramebuffers(1, &_memFrameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER,_memFrameBuffer);

glFramebufferTexture2D(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,
GL_TEXTURE_2D,
_textureId, 0);

GLenum status =glCheckFramebufferStatus(GL_FRAMEBUFFER) ;

if(status !=GL_FRAMEBUFFER_COMPLETE)
{
NSLog(@"failed to make complete framebuffer object %x", status);
}
}

范例工程：
LxOpenglES_RenderToTexture