Calling a C++ class from within a view controller crashes
I have a C++ object that I'm getting the reference to in my view controller like this:
m_applicationEngine = (ApplicationEngine *)[(GLView *)[self.parentViewController view] m_applicationEngine];
In my location delegate I call a methid in the class like this:
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {
CLLocationCoordinate2D coordinate = [newLocation coordinate];
NSLog(@"Location acquired %f, %f", coordinate.latitude, coordinate.longitude);
myLocation = new Location(coordinate.latitude, coordinate.longitude);
m_applicationEngine->GotoLoc(myLocation);
}
It does call the GotoLoc function but it crashes the first time the function accesses a public member variable of the m_applicationEngine instance. I'm positive the member has already been initialized. Anyone have any ideas?
m_applicationEngine is a C++ object 开发者_运维问答initialized in initWithFrame() in GLView:UIView.
m_applicationEngine = new ApplicationEngine(m_renderingEngine, self);
Here's the code of GotoLoc(). The first time it references m_rotation which is a member variable of the class it crashes. I can call GotoLoc() in other areas of the code, just not in the above Obj-C delegate function.
void ApplicationEngine::GotoLoc(Location *location) {
vec3 eye = vec3(0, 0, 1);
vec3 end = location->loc;
// Compute the difference between where we're looking at now vs. where we want to point
mat4 transpose;
MatrixTranspose(transpose, m_rotation);
MatrixVec3Multiply(eye, eye, transpose);
//cout << "Inverse. I was here x:" << relativeVec.x << " y:" << relativeVec.y << " z:" << relativeVec.z << endl;
// bring vectors down to the equator to measure x angle
vec3 relativeX = vec3(eye.x, 0, eye.z);
// reference vector is the rotation axis for the sign to be correct
float xAngle = signed_angle(relativeX, vec3(end.x, 0, end.z), vec3(0,-1,0));
mat4 rotationX;
MatrixRotationY(rotationX, -1 * xAngle);
MatrixMultiply(m_rotation, rotationX, m_rotation);
// need to rotate eye vector to line up on y with new target to measure y angle
MatrixTranspose(transpose, rotationX);
MatrixVec3Multiply(eye, eye, transpose);
float yAngle = signed_angle(eye, end, vec3(1,0,0));
cout << "Went to difference of: ANGLE x: " << RADIANS_TO_DEGREES(xAngle) << " y:" << RADIANS_TO_DEGREES(yAngle) << endl;
mat4 rotationY;
MatrixRotationX(rotationY, -1 * yAngle);
MatrixMultiply(m_rotation, m_rotation, rotationY);
}
Best guess on the information you have given us is that m_applicationEngine is actually not a C++ object. Where do you create it? in init? in the accessor m_applcationEngine?
If you want a better answer than that, show us the code of GotoLoc() and how you init the C++ object.
Edit (following new posted code):
I think m_applicationEngine
is null. You should be able to confirm that by putting a break on the first line of GotoLoc()
and checking the this
(is that right for C++? I want the equivalent to self
) pointer.
If your view is in a nib file, I have a feeling initWithCoder:
is used instead of initWithFrame:
which would explain why your C++ object is never constructed. The easiest way to fix this is to create and access it through a property and initialise it on first use e.g.
// .h file
@property (readonly, assign) ApplicationEngine* applicationEngine;
// .m file
-(ApplicationEngine*) applicationEngine
{
if (m_applicationEngine == NULL)
{
m_applicationEngine = new ApplicationEngine(m_renderingEngine, self);
}
return m_applicationEngine;
}
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