Hi,

I am new to OpenGL over iPhone. I am developing an iPhone app similar to a barcode reader but with an extra OpenGL layer. The bottommost layer is UIImagePickerController, then I use UIView on top and draw a rectangle at certain co-ordinates on the iphone screen. So far everything is OK. Then I am trying to draw an OpenGL 3-D model in that rectangle. I am able to load a 3-D model in the iPhone based on this code here - http://iphonedevelopment.blogspot.com/2008/12/start-of-wavefront-obj-file-loader.html

I am not able to transform the co-ordinates of the rectangle into OpenGL co-ordinates. Appreciate any help.

Do I need to use a matrix to translate the currentPosition of the 3-D model so it is drawn within myRect? The code is given below.. Appreciate any help/pointers in this regards.

John

-(void)setupView:(GLView*)view { const GLfloat zNear = 0.01, zFar = 1000.0, fieldOfView = 45.0; GLfloat size; glEnable(GL_DEPTH_TEST); glMatrixMode(GL_PROJECTION);

size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0); 
CGRect rect = view.bounds; 
glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size / 
           (rect.size.width / rect.size.height), zNear, zFar); 

glViewport(0, 0, rect.size.width, rect.size.height);  
glMatrixMode(GL_MODELVIEW);

glLoadIdentity(); 

glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
NSString *path = [[NSBundle mainBundle] pathForResource:@"plane" ofType:@"obj"];
OpenGLWaveFrontObject *theObject = [[OpenGLWaveFrontObject alloc] initWithPath:path];
Vertex3D position;
position.z = -8.0;
position.y = 3.0;
position.x = 2.0;
    theObject.currentPosition = position;
self.plane = theObject;
[theObject release];

}

• (void)drawView:(GLView*)view; { static GLfloat rotation = 0.0;

  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); glColor4f(0.0, 0.5, 1.0, 1.0); // the coordinates of the rectangle are // myRect.x, myRect.y, myRect.width, myRect.height // Do I need to use a matrix to translate the currentPosition of the // 3-D model so it is drawn within myRect? //glOrthof(-160.0f, 160.0f, -240.0f, 240.0f, -1.0f, 1.0f); [plane drawSelf]; }