Thread: OpenGL lighting problems

I think I'm having problems with the following:

Code:

    pos4[0] = 0.5, pos4[1] = 0.5, pos4[2] = 0.5, pos4[3] = 1.0;
    glLightfv(GL_LIGHT1, GL_AMBIENT, pos4);

    pos4[0] = 1.0, pos4[1] = 1.0, pos4[2] = 1.0, pos4[3] = 1.0;
    glLightfv(GL_LIGHT1, GL_DIFFUSE, pos4);

    pos4[0] = 1.0, pos4[1] = 1.0, pos4[2] = -200.0, pos4[3] = 1.0;
    glLightfv(GL_LIGHT1, GL_POSITION, pos4);

    glEnable(GL_LIGHT1);

    glEnable(GL_LIGHTING);

Also, uncomment out that section on the above section in the .zip, I uncommented it to get the screenshot.

Thanks again.

I haven't done much with OpenGL lights, but what I can tell you is this, when the light is off, it is using the glcolor3dv which you set up in the gllib.c file, and when the light is off it uses a meterial which you define I think in the init_game() function, so that would explain why when the light is off the have different colours from when it is on, but I am not 100% and I can't say that I am very good either :P

Just reading my OpenGL book again, perhaps I need to define a material? Would that make a difference?

OK, so now that I set a material, it works. However, the light is a bit bright, any more suggestions?

Make its colour darker.

To organize it a little better instead of reusing the pos array you should make an array for each color you want and make them global

ex

Code:

float squarePos[] = {3.0, 0.0, -4.0, 1.0};
float squareAmbient[] = {0.1, 0.2, 0.3};
float squareDiffuse[] = { 0.4, 0.4, 0.1};
float squareSpecular[] = {0.4, .04, 0.4};

also you need to at most position the light by

Code:

glLightfv{GL_LIGHT1, GL_POSITION, squarePos};

The first three values in the squarePos array are the x, y, z coordinates, and the third indicating whether it's positional or not. 0 indicate's it's infinitely far away, while 1 indicate's it has a finite distance.

I can't remember the parameters passed to a meterial creation function, but one of the parameters defines the brightness . . . Diffuse I think may be it, but I can't be sure

glMaterial and glColorMaterial are only used on the object. for glMaterial you specify a face (GL_FRONT_AND_BACK ususally), the lighting attribute(specular, ambient, diffuse), and the vector specifying' it's color.

A better way I think is to use glColorMaterial, which you have to enable. You specify it as such

Code:

glEnable(GL_COLOR_MATERIAL);
glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT);
glColor4f(1, 0, 0, .5);
glColorMaterial(GL_FRONT_AND_BACK, GL_SPECULAR);
//..etc

//draw your object with those attributes.

Well, you see, when I rotate the cube, the _entire_ cube color changes. Not just the face facing the light. I'll post screenshots as soon as I can. I am working out of NeHe and a book called "OpenGL game development", by the creators of GameDev.

Thanks again.

Thanks Indigo. I'll try that as soon as I can, probably later on today.