NeHe OpenGL Lesson16 - Cool Looking Fog

This sample shows us how to use OpenGL fog feature. we will learn how to use 3 different fog filters, how to change the color of the fog, and how to set how far into the screen the fog starts and how far into the screen it ends. And we could also grab some ideas on how to use per-vertex or per-pixel fog effect if you check what function glHint(GL_FOG_HINT, GL_DONT_CARE) works for.

For some inputs, you could press ‘F’ for switch texture filtering mode, ‘L’ for toggle lighting on or off, and arrow keys to rotate the texture cube.
Here is the core source code for using fog effect with OpenGL:

glFogi(GL_FOG_MODE, fogMode[fogfilter]);        // Fog Mode
glFogfv(GL_FOG_COLOR, fogColor);            // Set Fog Color
glFogf(GL_FOG_DENSITY, 0.35f);                // How Dense Will The Fog Be
glHint(GL_FOG_HINT, GL_DONT_CARE);            // Fog Hint Value
glFogf(GL_FOG_START, 1.0f);                // Fog Start Depth
glFogf(GL_FOG_END, 5.0f);                // Fog End Depth
glEnable(GL_FOG);                    // Enables GL_FOG

The above lines of code should be very self-explain. You could understand what they means for easily if you had some experience of writing fog in the shader.

 

The full source code could be downloaded from here.