CareerCup

Describe the Flyweight and Visitor design pattern with example

You have a vector of 128 floats (float data[128]) in shared memory, an environment with 8 threads and a convenient function called barrier() that will block on each thread until it will be signaled by all 8 threads (a simple semaphore of 8 elements).

Write a pseudo-C parallel function that calculates the sum of all 128 elements storing it inside data[0]; the function can alter/destroy the content of the other 127 elements of data[].

thread_id goes from 0 to 7: it is constant and unique for each of the 8 threads.

Consider the following 3D scene representing an old town's main square:
• A single statue
o static geometry, high polygon count
o low complexity fragment shader
• A particle system simulating smoke
o animated, rendered as a large set of points
• A small set of characters
o animated geometry, medium polygon count
o medium complexity fragment shader
• A large set of buildings
o static geometry, low polygon count
o low complexity fragment shader
• A background image/skybox
• The camera/viewpoint is continuously moving within the scene.

How would you render the statue - by itself – using OpenGL to achieve maximum vertex performance (vertices/second)?

How would you render the particle system - by itself - using OpenGL to achieve maximum vertex performance (vertices/second)?

How would you render the scene - as a whole - most efficiently on a GPU using OpenGL?

Given that the 3D scene was being rendered correctly but that you wanted to improve the performance further, how would you determine if the main performance limitation/bottleneck was located in the application, in the vertex processing stage, or in the fragment processing stage?