View Full Version : Colorblending

03-15-2012, 12:53 AM
I want to see white from background. How? Even with this:
glblend online tool (http://www.andersriggelsen.dk/glblendfunc.php)
I couldn't figure it out.
Thanks Michael

03-15-2012, 03:18 AM
1) you are clearly not an advanced GL programmer
2) I couldn't figure out what your actual question is. Maybe a picture could help if you are not comfortable with words.

03-15-2012, 05:42 AM
so I hope you are...

I draw onto an instrument panel and want the white to be seen through my drawing. It's a dll so i cannot change the instrument only draw on top.

I've tried to remove the black background of the instrument and place my drawing behind but the instrument's white is blurred. No idea why, that's why I want to draw on top.

03-15-2012, 06:19 AM
What I hinted (maybe too subtly) was that being a beginner in GL, you should have posted in the beginner section.

Then I see that you asked a similar question in a previous topic, but still nobody could help you. Probably because your question is not clear.

It seeems like there is a lot of unknowns in you environment. For people to help you, you have to be very specific so that the whole environment is clear.

At minimum, post pictures that demonstrate the problem !
Then :
- what do you want to draw ?
- do you want it above or below the existing rendering ?
- is it opaque ? translucent ? A non-rectangular decal sprite ?
- what do you mean by blurred ?
- show your code !
- show pictures, both normal instrument, then with black background removed, then with your current drawing.

03-15-2012, 08:20 AM
I draw 2D terrain with glpoints. Now I can set alpha to 0.5 and see the white instrument numbers/descriptions behind but like that the colors are not very good. Hence I wonder if I could see only the white from below through blending.

03-15-2012, 04:00 PM
If you wish to see the text from an overlay a simple method is to create a frag shader to use when render the text

in vec4 vColour; // from vertex shader

layout(location = 0, index = 0) out vec4 fFragColour;

void main()
if (vColour != vec4(1,1,1,1))

fFragColour = vColour;