Pro OpenGL ES for iOS

254 CHAPTER 8: Putting It All Together^

gluLookAt(m_Eyeposition.x,m_Eyeposition.y,m_Eyeposition.z,

targetLocation.x,targetLocation.y,targetLocation.z,

0.0,1.0,0.0);

}

-(GLKVector3)getEyeposition

{

return m_Eyeposition;

}

-(void)setEyeposition:(GLKVector3)loc

{

m_Eyeposition=loc;

}

In normal OpenGL, I’ve mentioned the existence of a utility library called GLUT.

Unfortunately, there is no complete GLUT library for iOS as of this writing, so I’ve had to

create my own where I stuff most any basic 3D utility method. With that in mind, create

a new object called miniglu.mm (the ‘‘mm’’ suffix lets the Objective C compiler

understand straight C code mixed with ObjC), add the the contents of Listing 8-6, and

add static GLKQuaternion m_Quaternion to the top of the file. And make sure to add

miniglu.h where needed.

This is kept as generic-C because GLUT is meant to be as portable as possible.

Listing 8-6. Two routines for miniGLU.mm

void gluLookAt(GLfloat eyex, GLfloat eyey, GLfloat eyez,

GLfloat centerx, GLfloat centery, GLfloat centerz,

GLfloat upx, GLfloat upy, GLfloat upz)

{

GLKVector3 up; //1

GLKVector3 from,to;

GLKVector3 lookat;

GLKVector3 axis;

float angle;

lookat.x=centerx; //2

lookat.y=centery;

lookat.z=centerz;

from.x=eyex;

from.y=eyey;

from.z=eyez;

to.x=lookat.x;

to.y=lookat.y;

to.z=lookat.z;

up.x=upx;

up.y=upy;

up.z=upz;