hmm, sometimes writing emails brings new ideas.
I replaced the two floats with one vec2 pass_other
and that works.
marius.
-----
uniform sampler2D texture;
varying vec2 texcoord0;
uniform vec4 hithresh; // hi and lo threshold
uniform vec4 lothresh;
uniform vec2 pass_other;
void main()
{
vec4 A = texture2D(texture, texcoord0);
A.a = pass_other[0];
if ((A.r >= hithresh.r) || (A.r <= lothresh.r))
{
A.a = pass_other[1];
}
gl_FragColor = A;
}
------------
marius schebella wrote:
> hi,
> is it possible to ask shader related questions on the pd list? I am
> trying to write pix_alpha as a shader, but for now I have problems with
> the glsl code. (maybe you can also point me to a shader forum or mailing
> list that you know is good?)
> I have a fragment shader, which is not working, and I don't know why.
> the problem is that "A.a = other" does not set the value correct (it
> always sets 0).
> If I write A.a = 0.5 for example, then it is working.
> The variables are passed correctly, all other variables work too, so I
> think it is really a problem of how glsl works, and an error in the
> code. what it should do is when the red pixel value is within a certain
> range, the alpha value should be set to the pass value, and if it is
> outside, it should be set to the other value. (similar to pix_alpha, but
> only with red at the moment)
> thanks,
> marius.
>
> ---------
> // red pix alpha
>
> uniform sampler2D texture;
> varying vec2 texcoord0;
>
> uniform vec4 hithresh; // hi and lo threshold
> uniform vec4 lothresh;
> uniform float pass;
> uniform float other;
>
> void main()
> {
> vec4 A = texture2D(texture, texcoord0);
> A.a = pass;
> if ((A.r >= hithresh.r) || (A.r <= lothresh.r))
> {
> A.a = other;
> }
> gl_FragColor = A;
> }
>
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