texture use

float a[]={0.1,0.5,0.9,0.4);
glTexEnvfv(GL_TEXTURE_ENV,GL_TEXTURE_ENV_COLOR,a);

glTexEnvI(GL_TEXTURE_ENV,GL_TEXTURE_MODE,BLEND);

glColor4f(0.9,0.5,0.1,0.8);

how these two color affact the ultimate apperance

I’ve included the table from the man page on texblend. It depends on the texture format but basically it uses the texture color as a blend between the interpolated polygon color and the constant texture environment color.

In your example the texture image will act as a weight to blend between the two colors:

float a[]={0.1,0.5,0.9,0.4);

glColor4f(0.9,0.5,0.1,0.8);

The results will depend on the image format in the texture, if it’s a luminance image you’ll only see images on a linear scale between teh two colors, but a color format will independently interpolate components.

From the table you can see that 0.0 in the texture gives all polygon color and 1.0 gives all texture environment color.

        +---------------+---------------+
        | Base Internal |   GL_BLEND    |
        |     Format    |               |
        +---------------+---------------+
        | GL_ALPHA      |C=Cf           |
        |               |A=AfAt         |
        +---------------+---------------+
        | GL_LUMINANCE  |C=Cf(1-Lt) +   |
        |               |CcLt           |
        |               |A=Af           |
        +---------------+---------------+
        | GL_LUMINANCE_ |C=Cf(1-Lt) +   |
        | ALPHA         |CcLt           |
        |               |A=AfAt         |
        +---------------+---------------+
        | GL_INTENSITY  |C=Cf(1-It) +   |
        |               |CcIt           |
        |               |A=Af(1-It) +   |
        |               |AcIt           |
        +---------------+---------------+
        | GL_RGB        |C=Cf(1-Ct) +   |
        |               |CcCt           |
        |               |A=Af           |
        +---------------+---------------+
        | GL_RGBA       |C=Cf(1-Ct) +   |
        |               |CcCt           |
        |               |A=AfAt         |
        +---------------+---------------+