@synthesizeclearColor =_clearColor;
-(void)setClearColor:(GLKVector4)clearColor
{
_clearColor= clearColor;
NSAssert(self== [[selfclass]currentContext],@"Receiving context required to be current context");
glClearColor(clearColor.r, clearColor.g, clearColor.b, clearColor.a);
}
-(GLKVector4)clearColor
{
return_clearColor;
}