COMPUTER SCIENCE AND ENGINEERING
COMPUTER GRAPHICS
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]


GL ____ PROJECTION


GL ____ MODELVIEW


Either A or B


None of the above

Detailed explanation1: The defaults in OpenGL are: the eye at (0, 0, 1); the center at (0, 0, 0) and the up is given by the positive direction of the Oy axis (0, 1, 0). Suppose that we have a generic C++ function that given the eye, the center and the up will return a 4x4 view matrix for us.
Detailed explanation2: OpenGL has 4 different types of matrices; GL MODELVIEW, GL PROJECTION, GL TEXTURE, and GL COLOR. You can switch the current type by using glMatrixMode() in your code.
Detailed explanation3: The default projection plane is the plane z = 0 and the direction of the projection is along the zaxis. Thus, objects within this box are visible and projected. In OpenGL, the modelview and projection matrices are concatenated together to form the matrix that applies to geometric entities such as vertices.
Detailed explanation4: The ModelView matrix contains both modelling and viewing transformations that place the viewer at the origin with the view direction aligned with the negative Z axis. Clip Coordinates result from transforming Eye Coordinates by the Projection matrix.