14. OpenGL Fog
Posted on : 25-03-2010 | By : Swiftless | In : OpenGL
Tags: fog, OpenGL, programming, tutorial
3
To get started we need some variables for the fog colour and
the density of the fog. I have done it with this:
GLfloat density = 0.3;
GLfloat fogColor[4] = {0.5, 0.5, 0.5, 1.0};
The fog colour is written in four parts, they cover the RGB values
Unfortunately I have been unable to find out what the fourth value
does. Next we have the density which sets how thick our fog is.
If you run the application you can acctually see that a density of 0.3 is acctually
quite thick.
After this we enable our fog and set its parameters.
First off we enable the fog.
glEnable (GL_FOG);
Now we set the fog mode, here i have set it to GL_EXP2, which is quite nice looking.
glFogi (GL_FOG_MODE, GL_EXP2);
Here we set the actual colour of our fog.
glFogfv (GL_FOG_COLOR, fogColor);
Now the density.
glFogf (GL_FOG_DENSITY, density);
And here I have set it up to look the nicest. In large projects, this may slow
down you application.
glHint (GL_FOG_HINT, GL_NICEST);
There are a few other options but I will explain them in the next Fog tutorial.
I will just let you get a grasp at this basic concept before I complicate it
just a little more.
If you have any problems, please email me at swiftless@gmail.com
| 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. | #include <GL/gl.h> #include <GL/glut.h> GLfloat angle = 0.0; GLfloat density = 0.3; //set the density to 0.3 which is GLfloat fogColor[4] = {0.5, 0.5, 0.5, 1.0}; //set the for void cube (void) { glRotatef(angle, 1.0, 0.0, 0.0); glRotatef(angle, 0.0, 1.0, 0.0); glRotatef(angle, 0.0, 0.0, 1.0); glColor3f(1.0, 0.0, 0.0); glutSolidCube(2); } void init (void) { glEnable (GL_DEPTH_TEST); //enable the depth testing glEnable (GL_FOG); //enable the fog glFogi (GL_FOG_MODE, GL_EXP2); //set the fog mode to GL_EXP2 glFogfv (GL_FOG_COLOR, fogColor); //set the fog color to glFogf (GL_FOG_DENSITY, density); //set the density to the glHint (GL_FOG_HINT, GL_NICEST); // set the fog to look the } void display (void) { glClearColor (0.0,0.0,0.0,1.0); glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); cube(); glutSwapBuffers(); angle ++; } void reshape (int w, int h) { glViewport (0, 0, (GLsizei)w, (GLsizei)h); glMatrixMode (GL_PROJECTION); glLoadIdentity (); gluPerspective (60, (GLfloat)w / (GLfloat)h, 1.0, 100.0); glMatrixMode (GL_MODELVIEW); } int main (int argc, char **argv) { glutInit (&argc, argv); glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH glutInitWindowSize (500, 500); glutInitWindowPosition (100, 100); glutCreateWindow (“A basic OpenGL Window“); init (); glutDisplayFunc (display); glutIdleFunc (display); glutReshapeFunc (reshape); glutMainLoop (); return 0; } |
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Heya, cool tutorials, keep them up!
btw, I think the fourth value in your fog color is the alpha value, obviously it will only make a change if you have blending enabled. Could be interesting to see if it blends with your glClearColor aye?
Hey, nice tutorials. On tutorial 14 “OpenGL Fog” The intro is repeated twice. Just so you know.
Thanks for the heads up Ted, I’ll fix that up.
Cheers,
Swiftless