OGL ignores glColor4f

OpenGL OpenGL: Basic Coding
1

Hello,

I tried to put the line :

glColor4f(1.0,0.0,0.0,0.9);

just after:

glBegin(GL_QUADS);

But still the quades are white… WHY???
Should I glEnable something?

I would be happy to get any ideas

Cheers,
Libby

2

Do you have texturing enabled?

Bad texture is rendered white.

Do you have lighting enabled, this may be undermining your efforts.

3

Thanks a lot,
But…
Now I comment out the line:

glEnable(GL_LIGHTING);

And it does display the colors, but it doesn’t display any light.

How can I have color AND light?

Libby

4

Hi Libby,
Enable GL_COLOR_MATERIAL, this uses your calls of glColor to set the material properties. Otherwise you will need to set up materials using glMaterial. For example:

glEnable(GL_LIGHTING);
glEnable(GL_COLOR_MATERIAL);
glColorMaterial(GL_FRONT, GL_DIFFUSE);
glColor4f(1, 0, 0, 1);

is the same as:

float diff[] = {1, 0, 0, 1};
glEnable(GL_LIGHTING);
glMaterialfv(GL_FRONT, GL_DIFFUSE, diff);

jimmi

5

Once you enable lighting you have two options to ensure your colour shows properly.

  1. Use glMaterial*() to specify colours.
  2. Use glEnable(GL_COLOR_MATERIAL) and glColorMaterial*(). Then your glColor*() calls will work.
6

Thanks Jimmie, You’re a genious! You made my day, now I can go home!

7

And thanks also to Furrage!