when i try to blend an object all the scene has been affected. for ex. i want to create a transparanced water in the scene.but only the water not the other objects.thanks a lot

Turn on blending only when you are going to draw something you want blended. For your example, you would draw the scene, then glEnable(GL_BLEND), then draw the water. It would be a good idea to disable blending after you''re done drawing all the blended stuff.

--Buzzy