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Antialiasing

Started by encom Dec 5, 2002 at 7:32 AM 3 replies 250+ views

Original Post

Dec 5, 2002 at 7:32 AM

Hi, I have a pb with line antialising. I display a 2D structure with plain polygons, then i display the same structure with Wired polygone to make a wired and solid display. if antialiasing is enabled, the lines (white color) use the black background color to make antialiasing, it doesnt use the color of the polygons. It''s ugly. How to chose the antialiasing color ?

vincoof

Dec 5, 2002 at 8:52 AM

There is no "antialiasing color". Line antialiasing (if you''re using GL_LINE_SMOOTH) just blends with the color of the pixel that is already rendered behind him.
You need to enable blending and to setup with something like that :
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

Also, the rendering order is important since I guess you''re using the Z-Buffer, n''est-ce pas ? You should render the wireframe model after the solid model.

encom

Author

encom

Dec 5, 2002 at 9:08 AM

I have ever done it, then blending is ok, and i draw the solid before the wire. It doesnt work.

vincoof

Dec 5, 2002 at 9:25 AM

Also, you should depth-test but not depth-write while you''re rendering the wireframe model :
glEnable(GL_DEPTH_TEST);
render_solid();
glDepthMask(GL_FALSE); // Don''t write to the depth buffer, but read it to test it anyway
render_wire();
glDepthMask(GL_TRUE); // Write to the depth buffer again

Also, the universal question : what is your graphics card / driver / OS combo ?

encom

Author

encom

Dec 5, 2002 at 9:35 AM

Woow,

thank you very much, it works now. thanks a lot :-)

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