Question 1 – Define a Callback function?

A callback function is a function that handle events. Callback functions determine exactly what function to call next when an event occurs.

Question 2 - When exactly is myDisplay()called? How do you get to your findings?

myDisplay() is called after glutDisplayFunc(myDisplay) is called as after this line is executed, my screen start to process it's drawing and updating of the graphics on the screen.

Question 3 – List the process to access the VRAM.

Define a struct to represent pixels on the screen.
Define pointer to memory location that will enable pixel plotting.
Based on the screen resolution, a 800x600 memory array is created.
Memory that was created earlier is then transfered into OpenGL’s double buffer.
Buffer will then be cleared to enable a clean surface to work on.
OpenGL’s double buffer will then copy the image onto the VRAM to be displayed on the screen.
Deleting the dynamic array created to prevent memory leak.

Question 4 - What color format are we using here i.e. 8 bits, 16 bits, 24 bits or 32 bits?

24bits. Red, Green and Blue.

Question 5 - How much memory have we allocated?

800*600*3=1.44MB

Question 7 – Describe what has glDrawPixel() done.

glDrawPixels() basically transfers what the buffer had stored into the display to enable the player to see the images. Plot-pixel basically just changes the data of the buffer.

As for what I've done.

I got a code to draw a circle, basically I have used point distance from the origin to determine where to plot the pixels.

Jay
Bleeding Visuals Author

Labels: practical