stuck at a very simple fragment shader


    Jul 11 2006 | 3:07 pm
    In my first attempt to modify a shader I'm already stuck:-/
    I try to add alpha blending to cf.blur.jxs like this:
    vec4 blur; vec4 color;
    blur = texture2DRect(image, texcoord11); blur += texture2DRect(image, texcoord00); blur += texture2DRect(image, texcoord02); blur += texture2DRect(image, texcoord20); blur += texture2DRect(image, texcoord22);
    blur *= 0.2;
    color.rgb = blur.rgb; color.a = gl_Color.a;
    gl_FragColor = color;
    This always results in alpha 1 regardless of the objects alpha color. While "color.a = 0.5;" gives me just what I'd expect.
    So gl_Color.a is not returning the objects alpha like I want it to. What am I missing here??
    -Thijs

    • Jul 11 2006 | 3:28 pm
      ok got it. you need to get the gl_Color in the vertex program and pass it on to the fragment program. Clearly my first shader attempt :-)
      -Thijs
      On 7/11/06, Thijs Koerselman wrote: > > In my first attempt to modify a shader I'm already stuck:-/ > > I try to add alpha blending to cf.blur.jxs like this: > > vec4 blur; > vec4 color; > > blur = texture2DRect(image, texcoord11); > blur += texture2DRect(image, texcoord00); > blur += texture2DRect(image, texcoord02); > blur += texture2DRect(image, texcoord20); > blur += texture2DRect(image, texcoord22); > > blur *= 0.2; > > color.rgb = blur.rgb; > color.a = gl_Color.a; > > gl_FragColor = color; > > > This always results in alpha 1 regardless of the objects alpha color. > While "color.a = 0.5;" gives me just what I'd expect. > > So gl_Color.a is not returning the objects alpha like I want it to. What > am I missing here?? > > -Thijs > >