GLuint filter; // Which Filter To Use
GLuint fogMode[]= { GL_EXP, GL_EXP2, GL_LINEAR }; // Types Of Fog
GLfloat fogColor[4]= {0.5f, 0.5f, 0.5f, 1.0f}; // Fog Color
..
..
..
..
..
glFogi(GL_FOG_MODE, fogMode[0]); // 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, 50.0f); // Fog End Depth
glEnable(GL_FOG); // Enables GL_FOG
Fog Filling in Entire Screen
Author
Hi
I'm having an issue with adding OpenGL fog to my 3D Engine. I am following lesson 16 from nehe and when I build and compile the source code all works fine. As you may know the Fog code is quiet small, so I have added it to the initialization part of my Engine.
Now the entire screen is filled with the color of the fog. If I switch to wireframe rendering I can see that the terrain/water and mesh are rendered, but they are all grey.
My ideal goal is to have fog under the water to add more realism with depth. In essence I want to have a cube of fog. This sounds like volumetric fog to me. I have tried to do this using the extension glFogCoordfEXT but this also fills the screen with the fog color when used in my engine, but this works correctly in the sample program.
To solve these issues have tried to comment out as much as possible, but the problem still persists.
Any other information I can think of which I wouldnt believe would cause a problem but might help
I am using glew32.dll
I am using VBO's whereas the sample programs render vertex by vertex
Thanks
is either
glFogf(GL_FOG_DENSITY, 0.35f); with GL_EXP, GL_EXP2
or
glFogf(GL_FOG_START, 1.0f); with GL_LINEAR
glFogf(GL_FOG_END, 50.0f);
ie not both
but for what u want youre best ignoring glfog altogether (incl glFogCoordfEXT)
+ look into methods of doing vol fog, theres prolly at least 5 methods u can achieve what u want depending on wether or not u want to use glsl etc
glFogf(GL_FOG_DENSITY, 0.35f); with GL_EXP, GL_EXP2
or
glFogf(GL_FOG_START, 1.0f); with GL_LINEAR
glFogf(GL_FOG_END, 50.0f);
ie not both
but for what u want youre best ignoring glfog altogether (incl glFogCoordfEXT)
+ look into methods of doing vol fog, theres prolly at least 5 methods u can achieve what u want depending on wether or not u want to use glsl etc
Author
Hi zedz
Thanks for your reply. Im glad to hear that my guess that I needed volumetric fog was correct. I have looked on gamedev and the following links
Volumetric Fog
Spherical Volume Fog
are pretty old and do not show any practical implementation, and elsewhere I look though google everything seems to use glFogCoordfEXT() which you advise against.
Do you have any links to good Volumetric Fog tutorials/implemtations from which I might learn, or if you have the knowledge would you mind dispencing some here.
Thanks
Ciarán
Thanks for your reply. Im glad to hear that my guess that I needed volumetric fog was correct. I have looked on gamedev and the following links
Volumetric Fog
Spherical Volume Fog
are pretty old and do not show any practical implementation, and elsewhere I look though google everything seems to use glFogCoordfEXT() which you advise against.
Do you have any links to good Volumetric Fog tutorials/implemtations from which I might learn, or if you have the knowledge would you mind dispencing some here.
Thanks
Ciarán
heres an old demo of mine
http://www.zedzeek.com/APPS/volumetric%20fog.rar
mouse button to move camera
i believe each vertice in the fog(underwater) i measure the dist to the camera, + then set the fog amount based on that,
youll prolly want something like the following for the final shading
color = texture * (1-fogamount) + fogamount*fogcolor
http://www.zedzeek.com/APPS/volumetric%20fog.rar
mouse button to move camera
i believe each vertice in the fog(underwater) i measure the dist to the camera, + then set the fog amount based on that,
youll prolly want something like the following for the final shading
color = texture * (1-fogamount) + fogamount*fogcolor
This topic is closed to new replies.
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