Step 1: Add the OpenGL framework to an empty cocoa application.
Step 2: Open the .xib file for the application and drag an NSOpenGLView into the window. Bring up the inspector and click on the identity tab. The Class name should be changed to 'MyOpenGLView'.
//Run at start
-(void)awakeFromNib
{
NSOpenGLPixelFormat *nsglFormat;
//Specify Attributes to allow screen to use various buffers
NSOpenGLPixelFormatAttribute attr[] =
{
//Enable Z sorting (make sure that polygons in front will overlap those in back)
NSOpenGLPFADoubleBuffer,
//Use Hardware Acceleration for graphics
NSOpenGLPFAAccelerated,
//Specify color depth
NSOpenGLPFAColorSize, BITS_PER_PIXEL,
//Specify Z depth
NSOpenGLPFADepthSize, DEPTH_SIZE,
//Anti-Aliasing:
NSOpenGLPFASampleBuffers, 8,
NSOpenGLPFASamples, 32,
NSOpenGLPFAMultisample,
0
};
//Set pixel format to include the attributes specified in the array attr[]
nsglFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:attr];
//Use the pixel format for the openGL view
[self setPixelFormat:nsglFormat];
//Initialize the view
[self initGL];
//Redraw view when window changes size
[self setPostsFrameChangedNotifications: YES];
//Update every 60 times a second
renderTimer = [NSTimer timerWithTimeInterval:1.0/60.0
target:self
selector:@selector(timerFired:)
userInfo:nil
repeats:YES];
//Activate timer to fire
[[NSRunLoop currentRunLoop] addTimer:renderTimer
forMode:NSDefaultRunLoopMode];
//Ensure timer fires during resize
[[NSRunLoop currentRunLoop] addTimer:renderTimer
forMode:NSEventTrackingRunLoopMode];
}
//Action to run when the timer is fired
- (void)timerFired:(id)sender
{
//Increase the rotation angle
rotTri += 1.0f;
//Tell the screen it needs to refresh
[self setNeedsDisplay:YES];
}
//Setup OpenGL view
- (void)initGL
{
printf("initGL\n");
// Synchronize buffer swaps with vertical refresh rate
GLint swapInt = 1;
[[self openGLContext] setValues:&swapInt forParameter:NSOpenGLCPSwapInterval];
//Apply Future Operations to The Projection Matrix
glMatrixMode(GL_PROJECTION);
//Reset The Projection Matrix
glLoadIdentity();
// Calculate The Aspect Ratio Of The Window
gluPerspective(45.0f,640.0f/480.0f,0.1f,100.0f);
//Select The Modelview Matrix
glMatrixMode(GL_MODELVIEW);
// Reset The Modelview Matrix
glLoadIdentity();
glShadeModel(GL_SMOOTH); //Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.0f); //set clear color to black
glClearDepth(1.0f); // Depth Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Test To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
}
//Function to draw a pyramid
static void drawAnObject()
{
//Draw a 3-sided pyramid
glBegin(GL_TRIANGLES);
//DAC (counterclockwise points)
glColor3f(1.0f, 0.0f,0.0f); //RED
glVertex3f(1.0f, -1.0f,-0.798f); //D
glColor3f(0.0f, 1.0f,0.0f); //GREEN
glVertex3f(0.0f, -0.333f,0.798f); //A
glColor3f(0.0f, 0.0f,1.0f); //BLUE
glVertex3f(-1.0f, -1.0f,-0.798f); //C
//DCB
glColor3f(1.0f, 0.0f,0.0f); //RED
glVertex3f(1.0f, -1.0f,-0.798f); //D
glColor3f(0.0f, 0.0f,1.0f); //BLUE
glVertex3f(-1.0f, -1.0f,-0.798f); //C
glColor3f(1.0f, 0.0f,1.0f); //Violet
glVertex3f(0.0f,1.0f,-0.798f); //B
//CAB
glColor3f(0.0f, 0.0f,1.0f); //BLUE
glVertex3f(-1.0f, -1.0f,-0.798f); //C
glColor3f(0.0f, 1.0f,0.0f); //GREEN
glVertex3f(0.0f, -0.333f,0.798f); //A
glColor3f(1.0f, 0.0f,1.0f); //Violet
glVertex3f(0.0f,1.0f,-0.798f); //B
//BAD
glColor3f(1.0f, 0.0f,1.0f); //Violet
glVertex3f(0.0f,1.0f,-0.798f); //B
glColor3f(0.0f, 1.0f,0.0f); //GREEN
glVertex3f(0.0f, -0.333f,0.798f); //A
glColor3f(1.0f, 0.0f,0.0f); //RED
glVertex3f(1.0f, -1.0f,-0.798f); //D
glEnd();
}
//Draw Loop
- (void) drawRect: (NSRect) bounds
{
//Clear the screen and depth buffer
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
//Reset the current modelview matrix
glLoadIdentity();
//Move along the x and z axis
glTranslatef( -1.0f, 0.0f, -5.0f );
//rotate the modelview matrix by an angle of rotTri around the vector <1,>
glRotatef( rotTri,1.0f, 1.0f, 1.0f );
//Draw a pyramid to the buffers
drawAnObject();
//Reset Modelview
glLoadIdentity();
glTranslatef( 1.2f, 0.5f, -5.0f );
glRotatef( -5.0f*rotTri,0.0f, 1.0f, 0.0f );
drawAnObject();
//Display the buffer content to the screen
[ [ self openGLContext ] flushBuffer ];
}
