How to use GLKMathProject? [GLKit - iOS]

Question

I tried:

int viewport[4];
viewport[0] = 0;
viewport[1] = 480;
viewport[2] = 320;
viewport[3] = 480;

GLKVector3 x = GLKMathProject(position, effect.transform.modelviewMatrix, effect.transform.projectionMatrix, viewport);

NSLog(@"%@", NSStringFromGLKVector3(x));

position is a GLKVector3 like this {3, 5, 6}

But it gives me some strange values: {1.52313e+12, 8.0313e+08, -160.131}

Answer 1

You left most of the viewport array uninitialized. You probably meant:

int viewport[4];
viewport[0] = 0;
viewport[1] = 480;
viewport[2] = 320;
viewport[3] = 480;

Or, shorter:

int viewport[4] = {0, 480, 320, 480};

Sidenote: Shouldn't it be {0, 0, 320, 480} (origin at 0, 0)?