FUNDAMENTALS OF COMPUTER GRAPHICS - PROJECT REPORT
Author: Valentin KAO valentin.kao@epitech.eu 张有请 - 2017280242
The purpose of this project is to implement an OpenGl program with particle system :
- The particle size varies and simulate a direction of snowflake
- Less snow at the beginning, slowly increasing over time
The video capture of my program named screenrecord.mp4, is available from the root of the folder. 0s -> 13s : Normal speed 13s -> 24s : Speed up a lot, to show that number of snowflakes increase. 24s -> End : normal speed with a lot of snowflakes
• GCC 5 or later • CMake 3.9 or later • OpenGL, GLUT and SOIL libraries. The code hasn't been tested on Windows but should work on Visual Studio 2015 and later.
From the folder in which you found this report, please enter the following command lines.
-
mkdir build && cd build -
cmake .. -
make
Once the compilated was successful, you can execute the program. Here is the usage of the program.
./SnowStorm [--width=x] [--height=y] [--title=”Assignment”]
width, w Set the width of the window 900 height, h Set the height of the window 900 title, t Set the title of the window “Assignment”
In order to implement future project easily, I define a simple application design. Those three classes are singletons avoiding any multiple instances.
Application class is in charge of parsing the arguments and to init the graphical core of the program with the input window size or the input window name.
GraphicalCore initializes OpenGL engine : window creation, keyboard handler, mouse handler, reshape handler, etc.
Engine is the core of the project : In change of enabling/disabling some features of OpenGL, it will contain the main function of update. It will also clear the window, setup the background and call the Particle Manager
ParticleManager will be the main engine of the particles. It will init all the particles by loading the texture, create the elements in a vector and render each elements of the vector.
If you look at the function Update of the Engine class, you will this algo- rithm :
- After activating GL_TEXTURE_2D, it draws the background by using drawing a square textured.
- It enables blending and texturing. It loads the texture if the texture is not loaded yet. Otherwise, it binds the texture loaded.
It calls then the function Render of ParticleManager by passing the deltaTime as parameter : Each particles has a position, a velocity and a size. The function Render updates the positions of the particles depending on their own velocities and the delta time. If the particle is out of the window, it resets its position to the top of the window instead of erasing it.
A new particle is created each 0.25 second.
By pressing the key ESC, you close the program properly. By pressing the arrow UP, the refresh speed of the window increases and snowflakes go down faster, otherwise, pressing the arrow DOWN decreases it.